Mark Nordhoff assisted in the design and implementation of tubing connections. Ellen Struve helped to select and acquire equipment used.

<ol>
	<li>Lyons, T. W., Reinhard, C. T., Planavsky, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+rise+of+oxygen+in+Earth's+early+ocean+and+atmosphere.">The rise of oxygen in Earth's early ocean and atmosphere.</a> Nature. 506 (7488), 307-315 (2014).</li><li>Raymond, J., Blankenship, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+origin+of+the+oxygen-evolving+complex.">The origin of the oxygen-evolving complex.</a> Coord. Chem. Rev. 252 (3-4), 377-383 (2008).</li><li>Kendall, B., Reinhard, C. T., Lyons, T., Kaufman, A. J., Poulton, S. W., Anbar, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pervasive+oxygenation+along+late+Archaean+ocean+margins.">Pervasive oxygenation along late Archaean ocean margins.</a> Nature Geosci. 3 (9), 647-652 (2010).</li><li>Olson, S. L., Kump, L. R., Kasting, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+the+areal+extent+and+dissolved+oxygen+concentrations+of+Archean+oxygen+oases.">Quantifying the areal extent and dissolved oxygen concentrations of Archean oxygen oases.</a> Chem. Geol. 362 (1), 35-43 (2013).</li><li>Satkoski, A. M., Beukes, N. J., Li, W., Beard, B. L., Johnson, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+redox-stratified+ocean+3.2+billion+years+ago.">A redox-stratified ocean 3.2 billion years ago.</a> Earth Planet. Sci. Lett. 430 (1), 43-53 (2015).</li><li>Holland, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oceans+-+Possible+Source+of+Iron+in+Iron-Formations.">Oceans - Possible Source of Iron in Iron-Formations.</a> Econ. Geol. 68 (7), 1169-1172 (1973).</li><li>Holland, H. D., Lazar, B., Mccaffrey, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+the+Atmosphere+and+Oceans.">Evolution of the Atmosphere and Oceans.</a> Nature. 320 (6057), 27-33 (1986).</li><li>Klein, C., Beukes, N. J., Schopf, J. W., Klein, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time+distribution,+stratigraphy,+and+sedimentologic+setting,+and+geochemistry+of+Precambrian+iron-formations.">Time distribution, stratigraphy, and sedimentologic setting, and geochemistry of Precambrian iron-formations.</a> The Proterozoic Biosphere. , 139-146 (1992).</li><li>Poulton, S. W., Canfield, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ferruginous+Conditions:+A+Dominant+Feature+of+the+Ocean+through+Earth's+History.">Ferruginous Conditions: A Dominant Feature of the Ocean through Earth's History.</a> Elements. 7 (2), 107-112 (2011).</li><li>Busigny, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+isotopes+in+an+Archean+ocean+analogue.">Iron isotopes in an Archean ocean analogue.</a> Geochim. Cosmochim. Acta. 133, 443-462 (2014).</li><li>Crowe, S. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photoferrotrophs+thrive+in+an+Archean+Ocean+analogue.">Photoferrotrophs thrive in an Archean Ocean analogue.</a> PNAS. 105 (41), 15938-15943 (2008).</li><li>Jones, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biogeochemistry+of+manganese+in+ferruginous+Lake+Matano,+Indonesia.">Biogeochemistry of manganese in ferruginous Lake Matano, Indonesia.</a> Biogeosciences. 8 (10), 2977-2991 (2011).</li><li>Lliros, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pelagic+photoferrotrophy+and+iron+cycling+in+a+modern+ferruginous+basin.">Pelagic photoferrotrophy and iron cycling in a modern ferruginous basin.</a> Sci. Rep. 5 (13803), (2015).</li><li>Koeksoy, E., Halama, M., Konhauser, K. O., Kappler, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+modern+ferruginous+habitats+to+interpret+Precambrian+banded+iron+formation+deposition.">Using modern ferruginous habitats to interpret Precambrian banded iron formation deposition.</a> Int. J. Astrobiol. , 1-13 (2015).</li><li>Canfield, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+model+for+Proterozoic+ocean+chemistry.">A new model for Proterozoic ocean chemistry.</a> Nature. 396 (6710), 450-453 (1998).</li><li>Wu, W. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+physiology+and+cell-mineral+interactions+of+the+marine+anoxygenic+phototrophic+Fe(II)+oxidizer+Rhodovulum+iodosum+-+implications+for+Precambrian+Fe(II)+oxidation.">Characterization of the physiology and cell-mineral interactions of the marine anoxygenic phototrophic Fe(II) oxidizer Rhodovulum iodosum - implications for Precambrian Fe(II) oxidation.</a> FEMS Microbiol. Ecol. 88 (3), 503-515 (2014).</li><li>Hungate, R. E., Macy, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Roll-Tube+Method+for+Cultivation+of+Strict+Anaerobes.">The Roll-Tube Method for Cultivation of Strict Anaerobes.</a> Bull. Ecol. Res. Comm. 17 (1), 123-126 (1973).</li><li>Van Baalen, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+marine+blue-green+algae.">Studies on marine blue-green algae.</a> Bot. mar. 4 (1-2), 129-139 (1962).</li><li>Sakamoto, T., Bryant, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+at+low+temperature+causes+nitrogen+limitation+in+the+cyanobacterium+Synechococcus+sp.+PCC+7002.">Growth at low temperature causes nitrogen limitation in the cyanobacterium Synechococcus sp. PCC 7002.</a> Arch. Microbiol. 169 (1), 10-19 (1998).</li><li>Swanner, E. D., Mloszewska, A. M., Cirpka, O. A., Schoenberg, R., Konhauser, K. O., Kappler, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+oxygen+production+in+Archaean+oceans+by+episodes+of+Fe(II)+toxicity.">Modulation of oxygen production in Archaean oceans by episodes of Fe(II) toxicity.</a> Nature Geosci. 8 (2), 126-130 (2015).</li><li>Stookey, L. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ferrozine+-+a+New+Spectrophotometric+Reagent+for+Iron.">Ferrozine - a New Spectrophotometric Reagent for Iron.</a> Anal. Chem. 42 (7), 779-784 (1970).</li><li>Fitch, M. W., Koros, W. J., Nolen, R. L., Carnes, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Permeation+of+Several+Gases+through+Elastomers,+with+Emphasis+on+the+Deuterium+Hydrogen+Pair.">Permeation of Several Gases through Elastomers, with Emphasis on the Deuterium Hydrogen Pair.</a> J. Appl. Polym. Sci. 47 (6), 1033-1046 (1993).</li><li>Smith, A. J. B., Beukes, N. J., Gutzmer, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Composition+and+Depositional+Environments+of+Mesoarchean+Iron+Formations+of+the+West+Rand+Group+of+the+Witwatersrand+Supergroup,+South+Africa.">The Composition and Depositional Environments of Mesoarchean Iron Formations of the West Rand Group of the Witwatersrand Supergroup, South Africa.</a> Econ. Geol. 108 (1), 111-134 (2013).</li><li>Johnson, C. M., Beard, B. L., Klein, C., Beukes, N. J., Roden, E. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+isotopes+constrain+biologic+and+abiologic+processes+in+banded+iron+formation+genesis.">Iron isotopes constrain biologic and abiologic processes in banded iron formation genesis.</a> Geochim. Cosmochim. Acta. 72 (1), 151-169 (2008).</li><li>Krepski, S. T., Emerson, D., Hredzak-Showalter, P. L., Luther, G. W., Chan, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphology+of+biogenic+iron+oxides+records+microbial+physiology+and+environmental+conditions:+toward+interpreting+iron+microfossils.">Morphology of biogenic iron oxides records microbial physiology and environmental conditions: toward interpreting iron microfossils.</a> Geobiology. 11 (5), 457-471 (2013).</li><li>Posth, N. R., Konhauser, K. O., Kappler, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbiological+processes+in+banded+iron+formation+deposition.">Microbiological processes in banded iron formation deposition.</a> Sedimentology. 60 (7), 1733-1754 (2013).</li><li>Maliva, R. G., Knoll, A. H., Simonson, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Secular+change+in+the+Precambrian+silica+cycle:+Insights+from+chert+petrology.">Secular change in the Precambrian silica cycle: Insights from chert petrology.</a> Geol. Soc. Am. Bull. 117 (7-8), 835-845 (2005).</li><li>Kappler, A., Pasquero, C., Konhauser, K. O., Newman, D. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deposition+of+banded+iron+formations+by+anoxygenic+phototrophic+Fe(II)-oxidizing+bacteria.">Deposition of banded iron formations by anoxygenic phototrophic Fe(II)-oxidizing bacteria.</a> Geology. 33 (11), 865-868 (2005).</li><li>Krepski, S. T., Hanson, T. E., Chan, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+characterization+of+a+novel+biomineral+stalk-forming+iron-oxidizing+bacterium+from+a+circumneutral+groundwater+seep.">Isolation and characterization of a novel biomineral stalk-forming iron-oxidizing bacterium from a circumneutral groundwater seep.</a> Environ. Microbiol. 14 (7), 1671-1680 (2012).</li><li>Czaja, A. D., Johnson, C. M., Beard, B. L., Roden, E. E., Li, W. Q., Moorbath, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+Fe+oxidation+controlled+deposition+of+banded+iron+formation+in+the+ca.+3770+Ma+Isua+Supracrustal+Belt+(West+Greenland).">Biological Fe oxidation controlled deposition of banded iron formation in the ca. 3770 Ma Isua Supracrustal Belt (West Greenland).</a> Earth. Planet. Sci. Lett. 363 (1), 192-203 (2013).</li><li>Melton, E. D., Schmidt, C., Kappler, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbial+iron(II)+oxidation+in+littoral+freshwater+lake+sediment:+the+potential+for+competition+between+phototrophic+vs.+nitrate-reducing+iron(II)-oxidizers.">Microbial iron(II) oxidation in littoral freshwater lake sediment: the potential for competition between phototrophic vs. nitrate-reducing iron(II)-oxidizers.</a> Front. Microbiol. 3 (197), 1-12 (2012).</li></ol>

Authors have nothing to disclose.

Microbial communities in the Precambrian ocean were regulated by, or modified as a result of, their activity and the prevailing geochemical conditions. In interpreting the origins of BIF, researchers generally infer the presence or activity of microorganisms based on the sedimentology or geochemistry of BIF, e.g., Smith et al.23 and Johnson et al.24. The study of modern organisms in modern environments that have geochemical analogs to ancient environments is also a valuabl...

The Precambrian (4.6 to 0.541 Gy ago) atmosphere experienced a gradual build-up of photosynthetically produced oxygen (O2), perhaps punctuated by step changes at the so-called &#34;Great Oxidation Event&#34; (GOE) at approximately 2.4 Gy ago, and again in the Neoproterozoic (1 to 0.541 Gy ago) as atmospheric O2 approached modern levels1. Cyanobacteria are the evolutionary remnants of the first organisms capable of oxygenic photosynthesis2. Geochemical evidence and modeling studies support the role of shallow coastal environments in harboring active communities of cyanobacteria or organisms capable of oxygenic photosynthesis or oxygenic phototrophs, generating local oxygen oases in the surface ocean below a predominantly anoxic atmosphere3-5.
The deposition of Banded Iron Formations (BIFs) from seawater throughout the Precambrian points to iron(II) (Fe(II)) as a major geochemical constituent of seawater, at least locally, during their deposition. Some of the largest BIFs are deep-water deposits, forming off the continental shelf and slope. The amount of Fe deposited is incompatible from a mass balance standpoint with predominantly continental (i.e., weathering) source. Therefore, much of the Fe must have been supplied from hydrothermal alteration of mafic or ultramafic seafloor crust6. Estimates of the rate of Fe deposited outboard of coastal environments are consistent with Fe(II) supplied to the surface ocean via upwelling7. In order for Fe to be transported in upwelling currents, must have been present in the reduced, mobile form &#8212; as Fe(II). The average oxidation state of Fe preserved in BIF is 2.4 8 and it is generally thought that BIF preserve Fe deposited as Fe(III), formed when upwelling Fe(II) was oxidized, possibly by oxygen. Therefore, exploring potential Fe(II) oxidation mechanisms along slope environments is important to understand how BIF formed. Moreover, refined geochemical characterization of marine sediments has identified that ferruginous conditions, where Fe(II) was present in an anoxic water column, were a persistent feature of the oceans throughout the Precambrian, and may not have been limited to just the time and place where BIF were deposited9. Therefore, for at least two billion years of Earth&#39;s history, redox interfaces between Fe(II) and O2 in the shallow oceans were likely commonplace.
Numerous studies utilize modern sites that are chemical and/or biological analogs of different features of the Precambrian ocean. A good example are ferruginous lakes where Fe(II) is stable and present in sunlit surface waters while photosynthetic activity (including by cyanobacteria) was detected10-13. The results of these studies provide insight into the geochemical and microbial characteristics of an oxic to anoxic/ferruginous chemocline. However these sites are generally physically stratified with little vertical mixing14, rather than the chemical interfaces occurring in an upwelling system, and are thought to support the most oxygen production in Precambrian time4.
A natural analogue to explore the development of a marine oxygen oasis beneath an anoxic atmosphere, and at an Fe(II)-rich upwelling system in sunlit surface water column is not available on the modern Earth. Therefore, a laboratory system that can simulate a ferruginous upwelling zone and also support the growth of cyanobacteria and photoferrotrophs is needed. The understanding and identification of microbial processes and their interaction with an upwelling aqueous medium that represents Precambrian seawater promotes the understanding and can complement the information gained from the rock record in order to fully understand the distinctive biogeochemical processes on ancient Earth.
Toward that end, a laboratory-scale column was designed in which Fe(II)-rich seawater medium (pH neutral) was pumped into the bottom of the column, and pumped out from the top. Illumination was provided at the top to create a 4 cm wide &#34;photic zone&#34; that supported the growth of cyanobacteria in the top 3 cm. Natural environments are generally stratified and stabilized by physicochemical gradients, like salinity or temperature. In order to stabilize the water column on a lab-scale, the column cylinder was packed with a porous glass bead matrix that helped to maintain the establishment of geochemical patterns that developed during the experiment. A continuous N2/CO2 gas flow was applied to flush the headspace of the column in order to maintain an anoxic atmosphere reflective of an ocean prior to the GOE15. After a constant flux of Fe(II) was established, cyanobacteria were inoculated throughout the column, and their growth was monitored by cell counts on samples removed through sampling ports. Oxygen was monitored in situ by placing oxygen-sensitive optode foils onto the inner wall of the column cylinder and measurements were made with an optical fiber from outside the column. Aqueous Fe speciation was quantified by removing samples from depth-resolved horizontal sampling ports and analyzed with the Ferrozine method. The abiotic control experiments and results demonstrate proof-of-concept &#8212; that a laboratory scale analog of the ancient water column, maintained in isolation from the atmosphere, is achievable. Cyanobacteria grew and produced oxygen, and the reactions between Fe(II) and oxygen were resolvable. Herein, the methodology for design, preparation, assembly, execution, and sampling of such a column are presented, along with results from an 84 hr run of the column while inoculated with the marine cyanobacterium Synechococcus sp. PCC 7002.

<table><tbody><tr><td>Widdel flask (5 L)</td><td>Ochs</td><td>110015</td><td>labor-ochs.de</td></tr><tr><td>Glass bottles (5 L)</td><td>Rotilabo</td><td>Y682.1</td><td>carlroth.com</td></tr><tr><td>Glass pipettes (5 ml)</td><td></td><td>51714</td><td>labor-ochs.de</td></tr><tr><td>0.22 &amp;micro;m Steritop filter unit (0.22&amp;nbsp;&amp;micro;m Polyethersulfone membrane)</td><td>Millipore</td><td>X337.1</td><td>carlroth.com</td></tr><tr><td>Aluminum foil</td><td></td><td></td><td></td></tr><tr><td>Sterile Luer Lock glass syringe, filled with cotton</td><td></td><td>C681.1</td><td>carlroth.com</td></tr><tr><td>Luer Lock stainless steel needles (150 mm, 1.0&amp;nbsp;mm ID)</td><td></td><td>201015</td><td>labor-ochs.de</td></tr><tr><td>NaCl</td><td>Sigma</td><td>433209</td><td>sigmaaldrich.com</td></tr><tr><td>MgSO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma</td><td>208094</td><td>sigmaaldrich.com</td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma</td><td>C4901</td><td>sigmaaldrich.com</td></tr><tr><td>NH&lt;sub&gt;4&lt;/sub&gt;Cl</td><td>Sigma</td><td>A9434</td><td>sigmaaldrich.com</td></tr><tr><td>KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma</td><td>P5655</td><td>sigmaaldrich.com</td></tr><tr><td>KBr</td><td>Sigma</td><td>P3691</td><td>sigmaaldrich.com</td></tr><tr><td>KCl</td><td>Sigma</td><td>P9541</td><td>sigmaaldrich.com</td></tr><tr><td>Glass cylinder</td><td></td><td>Y310.1</td><td>carlroth.com</td></tr><tr><td>Glass wool</td><td></td><td>7377.2</td><td>carlroth.com</td></tr><tr><td>Glass beads (&amp;oslash; 0.55 - 0.7&amp;nbsp;mm)</td><td></td><td>11079105</td><td>biospec.com</td></tr><tr><td>Butyl rubber stopper (&amp;oslash; 1.2 cm)</td><td></td><td>271024</td><td>labor-ochs.de</td></tr><tr><td>Petri Dish, glass (&amp;oslash; 8.0&amp;nbsp;cm)</td><td></td><td>T939.1</td><td>carlroth.com</td></tr><tr><td>Polymers glue</td><td></td><td>OTTOSEAL S68</td><td>adchem.de</td></tr><tr><td>Optical oxygen sensor foil (for oxygen analysis, see below)</td><td></td><td>&amp;ndash; on request &amp;ndash;</td><td>presens.de</td></tr><tr><td>Rubber tubing (35 mm, 7&amp;nbsp;mm ID)</td><td></td><td>770350</td><td>labor-ochs.de</td></tr><tr><td>Luer Lock tube connector (3.0 mm, Luer lock male = LLM)</td><td></td><td>P343.1</td><td>carlroth.com</td></tr><tr><td>Luer Lock tube connector (3.0 mm, Luer lock female = LLF)</td><td></td><td>P335.1</td><td>carlroth.com</td></tr><tr><td>Rubber tubing (25 mm, 0.72 mm ID)</td><td></td><td>2600185</td><td>newageindustries.com</td></tr><tr><td>Rubber tubing (50 mm, 7&amp;nbsp;mm ID)</td><td></td><td>770350</td><td>labor-ochs.de</td></tr><tr><td>Luer Lock stainless steel needle (150 mm, 1.0 mm ID)</td><td></td><td>201015</td><td>labor-ochs.de</td></tr><tr><td>Luer Lock glass syringe (10 ml)</td><td></td><td>C680.1</td><td>carlroth.com</td></tr><tr><td>Loose cotton&amp;nbsp;</td><td></td><td>&amp;ndash;</td><td></td></tr><tr><td>Butyl rubber stopper (&amp;oslash; 1.75 cm)</td><td></td><td>271050</td><td>labor-ochs.de</td></tr><tr><td>Stainless steel needle (40 mm, 1.0&amp;nbsp;mm ID)</td><td>Sterican</td><td>4665120</td><td>bbraun.de</td></tr><tr><td>Luer Lock stainless steel needle (150 mm, 1.5 mm ID)</td><td></td><td>201520</td><td>labor-ochs.de</td></tr><tr><td>position: Luer Lock female connector part at C.7</td><td></td><td></td><td></td></tr><tr><td>Polymers glue</td><td></td><td>OTTOSEAL S68</td><td>adchem.de</td></tr><tr><td>Stainless steel needle (120 mm, 0.7 mm ID)</td><td>Sterican</td><td>4665643</td><td>bbraun.de</td></tr><tr><td>Rubber tubing (40 mm, 0.74 mm ID)</td><td></td><td>2600185</td><td>newageindustries.com</td></tr><tr><td>Heat shrink tubing (35&amp;nbsp;mm, 3 mm ID shrunk)</td><td></td><td>541458 - 62</td><td>conrad.de</td></tr><tr><td>Tube clamp</td><td></td><td>STHC-C-500-4</td><td>tekproducts.com</td></tr><tr><td>Luer Lock tube connector (1.0 mm, LLF)</td><td></td><td>P334.1</td><td>carlroth.com</td></tr><tr><td>Luer Lock plastic cap (LLM)</td><td></td><td>CT69.1</td><td>carlroth.com</td></tr><tr><td>Glass bottle (5 L)</td><td>Rotilabo</td><td>Y682.1</td><td>carlroth.com</td></tr><tr><td>Butyl rubber stopper (for GL45)</td><td></td><td>444704</td><td>labor-ochs.de</td></tr><tr><td>Stainless steel capillary (300 mm, 0.74 mm ID)</td><td></td><td>56736</td><td>sigmaaldrich.com</td></tr><tr><td>Stainless steel capillary (50 mm, 0.74 mm ID)</td><td></td><td>56737</td><td>sigmaaldrich.com</td></tr><tr><td>Shrink tubing (35 mm, 3&amp;nbsp;mm ID shrunk)</td><td></td><td>541458 - 62</td><td>conrad.de</td></tr><tr><td>Rubber tubing (100 mm, 0.74 mm ID)</td><td></td><td>2600185</td><td>newageindustries.com</td></tr><tr><td>Luer Lock tube connector (1.0 mm, LLF)</td><td></td><td>P334.1</td><td>carlroth.com</td></tr><tr><td>Luer Lock glass syringe (10 ml)</td><td></td><td>C680.1</td><td>carlroth.com</td></tr><tr><td>Loose cotton&amp;nbsp;</td><td></td><td>&amp;ndash;</td><td></td></tr><tr><td>Butyl rubber stopper (&amp;oslash; 1.75 cm)</td><td></td><td>271050</td><td>labor-ochs.de</td></tr><tr><td>Stainless Steel needle (40 mm, 0.8&amp;nbsp;mm ID)</td><td>Sterican</td><td>4657519</td><td>bbraun.de</td></tr><tr><td>Luer lock glass syringe (5 ml)</td><td></td><td>C679.1</td><td>carlroth.com</td></tr><tr><td>Butyl rubber stopper (&amp;oslash; 1.75 mm)</td><td></td><td>271050</td><td>labor-ochs.de</td></tr><tr><td>Rubber tubing (40 mm, 0.74 mm ID)</td><td></td><td>2600185</td><td>newageindustries.com</td></tr><tr><td>Glass bottle (2 L)</td><td>Rotilabo</td><td>X716.1</td><td>carlroth.com</td></tr><tr><td>Butyl rubber stopper (for GL45)</td><td></td><td>444704</td><td>labor-ochs.de</td></tr><tr><td>Stainless steel capillary (50 mm, 0.74 mm ID)</td><td></td><td>56736</td><td>sigmaaldrich.com</td></tr><tr><td>Rubber tubing (30 mm x 0.74 mm ID)</td><td></td><td>2600185</td><td>newageindustries.com</td></tr><tr><td>Rubber tubing (100 mm x 0.74 mm ID)</td><td></td><td>2600185</td><td>newageindustries.com</td></tr><tr><td>Luer Lock tube connector (1.0 mm, LLF)</td><td></td><td>P334.1</td><td>carlroth.com</td></tr><tr><td>Luer Lock 3-way connector (LLF, 2x LLM)</td><td></td><td>6134</td><td>cadenceinc.com</td></tr><tr><td>Light source</td><td>Samsung</td><td>SI-P8V151DB1US</td><td>samsung.com</td></tr><tr><td>Peristalic pump</td><td>Ismatec</td><td>EW-78017-35</td><td>coleparmer.com</td></tr><tr><td>Pumping tubing (0.89&amp;nbsp;mm ID)</td><td></td><td>EW-97628-26</td><td>coleparmer.com</td></tr><tr><td>Stainless steel capillary (200 mm, 0.74 mm ID)</td><td></td><td>56736</td><td>sigmaaldrich.com</td></tr><tr><td>Stainless steel capillary (400 mm, 0.74 mm ID)</td><td></td><td>56737</td><td>sigmaaldrich.com</td></tr><tr><td>Supel-Inert Foil (Tedlar - PFC) gas pack (10 L)</td><td></td><td>30240-U</td><td>sigmaaldrich.com</td></tr><tr><td>Rubber tube (30 mm, 6&amp;nbsp;mm ID)</td><td></td><td>770300</td><td>labor-ochs.de</td></tr><tr><td>Luer Lock tube connector (3.0 mm, LLM)</td><td></td><td>P343.1</td><td>carlroth.com</td></tr><tr><td>Luer Lock tube connector (3.0 mm, LLF)</td><td></td><td>P335.1</td><td>carlroth.com</td></tr><tr><td>Gas-tight syringe (20&amp;nbsp;ml)</td><td></td><td>C681.1</td><td>carlroth.com</td></tr><tr><td>Bunsen burner</td><td></td><td>&amp;ndash;</td><td></td></tr><tr><td>Fiber optic oxygen meter for oxygen quantification</td><td>Presens</td><td>TR-FB-10-01</td><td>presens.de</td></tr><tr><td>Vacuum pump</td><td></td><td>&amp;ndash;</td><td></td></tr><tr><td>Silicone glue for oxygen optodes</td><td>Presens</td><td>PS1</td><td>presens.de</td></tr></tbody></table>

laboratory simulation of an iron(ii)-rich precambrian marine upwelling system to explore the growth of photosynthetic bacteria

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling from hydrothermal sources in the Precambrian ocean was oxidized by molecular oxygen [O2] produced by cyanobacteria. The oldest BIFs, deposited prior to the Great Oxidation Event (GOE) at about 2.4 billion years (Gy) ago, could have formed by direct oxidation of Fe(II) by anoxygenic photoferrotrophs under anoxic conditions. As a method for testing the geochemical and mineralogical patterns that develop under different biological scenarios, we designed a 40 cm long vertical flow-through column to simulate an anoxic Fe(II)-rich marine upwelling system representative of an ancient ocean on a lab scale. The cylinder was packed with a porous glass bead matrix to stabilize the geochemical gradients, and liquid samples for iron quantification could be taken throughout the water column. Dissolved oxygen was detected non-invasively via optodes from the outside. Results from biotic experiments that involved upwelling fluxes of Fe(II) from the bottom, a distinct light gradient from top, and cyanobacteria present in the water column, show clear evidence for the formation of Fe(III) mineral precipitates and development of a chemocline between Fe(II) and O2. This column allows us to test hypotheses for the formation of the BIFs by culturing cyanobacteria (and in the future photoferrotrophs) under simulated marine Precambrian conditions. Furthermore we hypothesize that our column concept allows for the simulation of various chemical and physical environments &#8212; including shallow marine or lacustrine sediments.

Control experiment
Abiotic control experiments (10 days) demonstrated consistently low oxygen concentrations (O2 &#60;0.15 mg/L) with no significant fluctuations in the Fe(II)-profile throughout the upwelling water column. The formation of precipitates (presumably Fe(III)(oxyhydr-)oxides) in the medium reservoir and the slight decrease in the overall Fe(II) concentration from 500 &#181;M to...

Watch this Scientific Journal Video about Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria at JoVE.com

Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

We simulated a Precambrian ferruginous marine upwelling system in a lab-scale vertical flow-through column. The goal was to understand how geochemical profiles of O2 and Fe(II) evolve as cyanobacteria produce O2. The results show the establishment of a chemocline due to Fe(II) oxidation by photosynthetically produced O2.

Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling ...

laboratory-simulation-an-iron-ii-rich-precambrian-marine-upwelling

Research

JoVE Journal

Environment

11.7K Views.  University of Tuebingen.  We gesimuleerd een Precambrium ijzerhoudende marine opwelling systeem in een lab-schaal verticale doorstroom kolom. Het doel was om te begrijpen hoe geochemische profielen van O 2 en Fe (II) evolueren cyanobacteriën produceren O 2. De resultaten tonen de instelling van een chemocline door Fe (II) oxidatie door fotosynthetisch geproduceerde O 2. 

Video: Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

A Small Volume Bioassay to Assess Bacterial/Phytoplankton Co-culture Using WATER-Pulse-Amplitude-Modulated (WATER-PAM) Fluorometry

Conventional methods for experimental manipulation of microalgae have employed large volumes of culture (20 ml to 5 L), so that the culture can be subsampled throughout the experiment1&#8211;7. Subsampling of large volumes can be problematic for several reasons: 1) it causes variation in the total volume and the surface area:volume ratio of the culture during the experiment; 2) pseudo-replication (i.e., replicate samples from the same treatment flask8) is often employed rather than true replicates (i.e., sampling from replicate treatments); 3) the duration of the experiment is limited by the total volume; and 4) axenic cultures or the usual bacterial microbiota are difficult to maintain during long-term experiments as contamination commonly occurs during subsampling.
The use of microtiter plates enables 1 ml culture volumes to be used for each replicate, with up to 48 separate treatments within a 12.65 x 8.5 x 2.2 cm plate, thereby decreasing the experimental volume and allowing for extensive replication without subsampling any treatment. Additionally, this technique can be modified to fit a variety of experimental formats including: bacterial-algal co-cultures, algal physiology tests, and toxin screening9&#8211;11. Individual wells with an alga, bacterium and/or co-cultures can be sampled for numerous laboratory procedures including, but not limited to: WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry, microscopy, bacterial colony forming unit (cfu) counts and flow cytometry. The combination of the microtiter plate format and WATER-PAM fluorometry allows for multiple rapid measurements of photochemical yield and other photochemical parameters with low variability between samples, high reproducibility and avoids the many pitfalls of subsampling a carboy or conical flask over the course of an experiment.

A Small Volume Bioassay to Assess Bacterial/Phytoplankton Co-culture Using WATER-Pulse-Amplitude-Modulated WATER-PAM Fluorometry

The goal of this procedure is to demonstrate the reproducibility and adaptability of using a microtiter plate format for microalgal screening. This rapid screen combines WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry to measure photosynthetic yield as an indicator of Photosystem II (PSII) health with small volume bacterial-algal co-cultures.

Conventional methods for experimental manipulation of microalgae have employed large volumes of culture (20 ml to 5 L), so that the culture can be ...

Quantification of Heavy Metals and Other Inorganic Contaminants on the Productivity of Microalgae

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages include high potential yield, use of non-arable land and integration with waste streams. The nutrient requirements of a large-scale microalgae production system will require the coupling of cultivation systems with industrial waste resources, such as carbon dioxide from flue gas and nutrients from wastewater. Inorganic contaminants present in these wastes can potentially lead to bioaccumulation in microalgal biomass negatively impact productivity and limiting end use. This study focuses on the experimental evaluation of the impact and the fate of 14 inorganic contaminants (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, V and Zn) on Nannochloropsis salina growth. Microalgae were cultivated in photobioreactors illuminated at 984 &#181;mol m-2 sec-1 and maintained at pH 7 in a growth media polluted with inorganic contaminants at levels expected based on the composition found in commercial coal flue gas systems. Contaminants present in the biomass and the medium at the end of a 7 day growth period were analytically quantified through cold vapor atomic absorption spectrometry for Hg and through inductively coupled plasma mass spectrometry for As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Sn, V and Zn. Results show N. salina is a sensitive strain to the multi-metal environment with a statistical decrease in biomass yieldwith the introduction of these contaminants. The techniques presented here are adequate for quantifying algal growth and determining the fate of inorganic contaminants.

Integration of microalgal cultivation with industrial flue gas will ultimately introduce heavy metals and other inorganic compounds into the growth media. This study presents a procedure used to determine the end fate and impact of heavy metals and inorganic contaminants on the growth of Nannochloropsis salina grown in photobioreactors.

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages ...

Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron (Oxy)Hydroxides, Trace Elements, and Bacteria

Fate and speciation of trace elements (TEs), such as arsenic (As) and mercury (Hg), in aquifers are closely related to physio-chemical conditions, such as redox potential (Eh) and pH, but also to microbial activities that can play a direct or indirect role on speciation and/or mobility. Indeed, some bacteria can directly oxidize As(III) to As(V) or reduce As(V) to As(III). Likewise, bacteria are strongly involved in Hg cycling, either through its methylation, forming the neurotoxin monomethyl mercury, or through its reduction to elemental Hg&#176;. The fates of both As and Hg are also strongly linked to soil or aquifer composition; indeed, As and Hg can bind to organic compounds or (oxy)hydroxides, which will influence their mobility. In turn, bacterial activities such as iron (oxy)hydroxide reduction or organic matter mineralization can indirectly influence As and Hg sequestration. The presence of sulfate/sulfide can also strongly impact these particular elements through the formation of complexes such as thio-arsenates with As or metacinnabar with Hg.
Consequently, many important questions have been raised on the fate and speciation of As and Hg in the environment and how to limit their toxicity. However, due to their reactivity towards aquifer components, it is difficult to clearly dissociate the biogeochemical processes that occur and their different impacts on the fate of these TE.
To do so, we developed an original, experimental, column setup that mimics an aquifer with As- or Hg-iron-oxide rich areas versus iron depleted areas, enabling a better understanding of TE biogeochemistry in anoxic conditions. The following protocol gives step by step instructions for the column set-up either for As or Hg, as well as an example with As under iron and sulfate reducing conditions.

Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron OxyHydroxides, Trace Elements, and Bacteria

Fate and speciation of arsenic and mercury in aquifers are closely related to physio-chemical conditions and microbial activity. Here, we present an original experimental column setup that mimics an aquifer and enables a better understanding of trace element biogeochemistry in anoxic conditions. Two examples are presented, combining geochemical and microbiological approaches.

Fate and speciation of trace elements (TEs), such as arsenic (As) and mercury (Hg), in aquifers are closely related to physio-chemical conditions, such as ...

Self-standing Electrochemical Set-up to Enrich Anode-respiring Bacteria On-site

Anaerobic respiration coupled with electron transport to insoluble minerals (referred to as extracellular electron transport [EET]) is thought to be critical for microbial energy production and persistence in many subsurface environments, especially those lacking soluble terminal electron acceptors. While EET-capable microbes have been successfully isolated from various environments, the diversity of bacteria capable of EET is still poorly understood, especially in difficult-to-sample, low energy or extreme environments, such as many subsurface ecosystems. Here, we describe an on-site electrochemical system to enrich EET-capable bacteria using an anode as a respiratory terminal electron acceptor. This anode is connected&#160;to a cathode capable of&#160;catalyzing abiotic oxygen reduction. Comparing this approach with electrocultivation methods that use a potentiostat for poising the electrode potential, the two-electrode system does not require an external power source. We present an example of our on-site enrichment utilized in an alkaline pond at the Cedars, a terrestrial serpentinization site in Northern California. Prior attempts to cultivate mineral reducing bacteria were unsuccessful, which is likely due to the low-biomass nature of this site and/or the low relative abundance of metal reducing microbes. Prior to implementing our two-electrode enrichment, we measured the vertical profile of dissolved oxygen concentration. This allowed us to place the carbon felt anode and platinum-electroplated carbon felt cathode at depths that would support anaerobic and aerobic processes, respectively. Following on-site incubation, we further enriched the anodic electrode in the laboratory and confirmed&#160;a distinct microbial community compared to the surface-attached or biofilm communities normally observed at the Cedars. This enrichment subsequently led to the isolation of the first electrogenic microbe from the Cedars. This method of on-site microbial enrichment has the potential to greatly enhance the isolation of EET-capable bacteria from low biomass or difficult to sample habitats.

On-site microbial enrichment or in situ cultivation techniques can facilitate the isolation of difficult-to-culture microbial taxa, especially from low-biomass or geochemically extreme environments. Here, we describe an electrochemical set-up without using an external power source to enrich microbial strains that are capable of extracellular electron transport (EET).

Anaerobic respiration coupled with electron transport to insoluble minerals (referred to as extracellular electron transport [EET]) is thought to be ...

Microalgae Cultivation and Biomass Quantification in a Bench-Scale Photobioreactor with Corrosive Flue Gases

Photobioreactors are illuminated cultivation systems for experiments on phototrophic microorganisms. These systems provide a sterile environment for microalgal cultivation with temperature, pH, and gas composition and flow rate control. At bench-scale, photobioreactors are advantageous to researchers studying microalgal properties, productivity, and growth optimization. At industrial scales, photobioreactors can maintain product purity and improve production efficiency. The video describes the preparation and use of a bench-scale photobioreactor for microalgal cultivation, including the safe use of corrosive gas inputs, and details relevant biomass measurements and biomass productivity calculations. Specifically, the video illustrates microalgal culture storage and preparation for inoculation, photobioreactor assembly and sterilization, biomass concentration measurements, and a logistic model for microalgal biomass productivity with rate calculations including maximum and overall biomass productivities. Additionally, since there is growing interest in experiments to cultivate microalgae using simulated or real waste gas emissions, the video will cover the photobioreactor equipment adaptations necessary to work with corrosive gases and discuss safe sampling in such scenarios.

Bench-scale, axenic cultivation facilitates microalgal characterization and productivity optimization before subsequent process scale-up. Photobioreactors provide the necessary control for reliable and reproducible microalgal experiments and can be adapted to safely cultivate microalgae with the corrosive gases (CO2, SO2, NO2) from municipal or industrial combustion emissions.

Photobioreactors are illuminated cultivation systems for experiments on phototrophic microorganisms. These systems provide a sterile environment for ...

Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the emergence of life. The growth of hydrothermal chimneys in a thermal gradient environment within an early Earth vent system was successfully simulated by using different hydrothermal simulants, such as sodium sulfide, which were injected into an early Earth ocean simulant containing dissolved ferrous iron. Moreover, an apparatus was developed to sufficiently cool the ocean simulant to near 0 &#176;C in a condenser vessel immersed in a cold water bath while injecting a sulfide solution at hot to room temperatures, effectively creating an artificial chimney structure in a temperature gradient environment over a period of a few hours. Such experiments with different chemistries and variable temperature&#160;gradients resulted in a variety of morphologies in the chimney structure. The use of ocean and hydrothermal fluid simulants at room temperature resulted in vertical chimneys, whereas the combination of a hot hydrothermal fluid and cold ocean simulant inhibited the formation of robust chimney structures. The customizable 3D printed condenser created for this study acts as a jacketed reaction vessel that can be easily modified and used by different researchers. It will allow the careful control of injection rate and chemical composition of vent and ocean simulants, which should help accurately simulate prebiotic reactions in chimney systems with thermal gradients similar to those of natural systems.

The goal of this protocol is to form simulated hydrothermal chimneys via chemical garden injection experiments and introduce a thermal gradient across the inorganic precipitate membrane, using a 3D printable condenser that can be reproduced for educational purposes.

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the ...

Using Flexible Gold-Titanium Reaction Cells to Simulate Pressure-Dependent Microbial Activity in the Context of Subsurface Biomining

Laboratory studies investigating subsurface microbial processes, such as metal leaching in deep ore deposits (biomining), share common and challenging obstacles, including the special environmental conditions that need to be replicated, e.g., high pressure and in some cases acidic solutions. The former requires an experimental setup suitable for pressurization up to 100 bar, while the latter demands a fluid container with high chemical resistance against corrosion and unwanted chemical reactions with the container wall. To meet these conditions for an application in the field of in situ biomining, a special flexible gold-titanium reaction cell inside a rocking high-pressure reactor was used in this study. The described system allowed simulation of in situ biomining through sulfur-driven microbial iron reduction in an anoxic, pressure-controlled, highly chemically inert experimental environment. The flexible gold-titanium reaction cell can accommodate up to 100 mL of sample solution, which can be sampled at any given time point while the system maintains the desired pressure. Experiments can be performed on timescales ranging from hours to months. Assembling the high-pressure reactor system is fairly time consuming. Nevertheless, when complex and challenging (microbiological) processes occurring in the earth&#39;s deep subsurface in chemically aggressive fluids have to be investigated in the laboratory, the advantages of this system outweigh the disadvantages. The results found that even at high pressure the microbial consortium is active, but at significantly lower metabolic rates.

This protocol describes microbial experiments under elevated pressures to study in situ biomining processes. The experimental approach employs a rocking high-pressure reactor equipped with a gold-titanium reaction cell containing a microbial culture in an acidic, iron-rich medium.

Laboratory studies investigating subsurface microbial processes, such as metal leaching in deep ore deposits (biomining), share common and challenging ...

Engineering

Construction and Setup of a Bench-scale Algal Photosynthetic Bioreactor with Temperature, Light, and pH Monitoring for Kinetic Growth Tests

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic performance of microalgae-based biofuel production. Models that estimate microalgal growth under different conditions can help to optimize PBR design and operation. To be effective, the growth parameters used in these models must be accurately determined. Algal growth experiments are often constrained by the dynamic nature of the culture environment, and control systems are needed to accurately determine the kinetic parameters. The first step in setting up a controlled batch experiment is live data acquisition and monitoring. This protocol outlines a process for the assembly and operation of a bench-scale photosynthetic bioreactor that can be used to conduct microalgal growth experiments. This protocol describes how to size and assemble a flat-plate, bench-scale PBR from acrylic. It also details how to configure a PBR with continuous pH, light, and temperature monitoring using a data acquisition and control unit, analog sensors, and open-source data acquisition software.

This paper describes the assembly process and operation of a bench-scale photosynthetic bioreactor that can be used, in conjunction with other methods, to estimate pertinent kinetic growth parameters. This system continuously monitors the pH, light, and temperature using sensors, a data acquisition and control unit, and open-source data acquisition software.

The optimal design and operation of photosynthetic bioreactors (PBRs) for microalgal cultivation is essential for improving the environmental and economic ...

Bioengineering

Establishment of Microbial Eukaryotic Enrichment Cultures from a Chemically Stratified Antarctic Lake and Assessment of Carbon Fixation Potential

Lake Bonney is one of numerous permanently ice-covered lakes located in the McMurdo Dry Valleys, Antarctica. The perennial ice cover maintains a chemically stratified water column and unlike other inland bodies of water, largely prevents external input of carbon and nutrients from streams. Biota are exposed to numerous environmental stresses, including year-round severe nutrient deficiency, low temperatures, extreme shade, hypersalinity, and 24-hour darkness during the winter 1. These extreme environmental conditions limit the biota in Lake Bonney almost exclusively to microorganisms 2.
Single-celled microbial eukaryotes (called "protists") are important players in global biogeochemical cycling 3 and play important ecological roles in the cycling of carbon in the dry valley lakes, occupying both primary and tertiary roles in the aquatic food web. In the dry valley aquatic food web, protists that fix inorganic carbon (autotrophy) are the major producers of organic carbon for organotrophic organisms 4, 2. Phagotrophic or heterotrophic protists capable of ingesting bacteria and smaller protists act as the top predators in the food web 5. Last, an unknown proportion of the protist population is capable of combined mixotrophic metabolism 6, 7. Mixotrophy in protists involves the ability to combine photosynthetic capability with phagotrophic ingestion of prey microorganisms. This form of mixotrophy differs from mixotrophic metabolism in bacterial species, which generally involves uptake dissolved carbon molecules. There are currently very few protist isolates from permanently ice-capped polar lakes, and studies of protist diversity and ecology in this extreme environment have been limited 8, 4, 9, 10, 5. A better understanding of protist metabolic versatility in the simple dry valley lake food web will aid in the development of models for the role of protists in the global carbon cycle.
We employed an enrichment culture approach to isolate potentially phototrophic and mixotrophic protists from Lake Bonney. Sampling depths in the water column were chosen based on the location of primary production maxima and protist phylogenetic diversity 4, 11, as well as variability in major abiotic factors affecting protist trophic modes: shallow sampling depths are limited for major nutrients, while deeper sampling depths are limited by light availability. In addition, lake water samples were supplemented with multiple types of growth media to promote the growth of a variety of phototrophic organisms.
RubisCO catalyzes the rate limiting step in the Calvin Benson Bassham (CBB) cycle, the major pathway by which autotrophic organisms fix inorganic carbon and provide organic carbon for higher trophic levels in aquatic and terrestrial food webs 12. In this study, we applied a radioisotope assay modified for filtered samples 13 to monitor maximum carboxylase activity as a proxy for carbon fixation potential and metabolic versatility in the Lake Bonney enrichment cultures.

Microbial eukaryotes are both a source of photosynthetically-derived carbon and top predatory species in permanently ice-covered Antarctic lakes. This report describes an enrichment culture approach to isolate metabolically versatile microbial eukaryotes from the Antarctic lake, Lake Bonney, and assesses inorganic carbon fixation potential using a radioisotope assay for Ribulose-1,5-bisphophate carboxylase oxygenase (RubisCO) activity.

Lake Bonney is one of numerous permanently ice-covered lakes located in the McMurdo Dry Valleys, Antarctica. The perennial ice cover maintains a ...

Biology

Operation of Laboratory Photobioreactors with Online Growth Measurements and Customizable Light Regimes

The laboratory study of microalgae can be experimentally challenging. In addition to the cultivation requirements of non-photosynthetic microorganisms, phototrophs also require illumination. Routinely, researchers seek to provide custom light supplies, i.e., vary the light intensity and time over which it is delivered. Such flexibility is difficult with standard benchtop lights. Usually, cultivation studies also require growth comparisons between experimental treatments. Frequently, growth is assessed over an extended duration, e.g., multiple times a day over a week-long trial. Manual measurements can be time-consuming and lack data resolution. Therefore, photobioreactors (PBRs) with automatic growth monitoring and customizable light supply are useful for replicated experiments with multiple treatments. The current work presents the design, construction, and operation of laboratory PBRs. The materials are easily sourced and relatively inexpensive. The design could be duplicated with moderate skill. Each structure has a footprint of ~40 cm2 and hosts three 1 L glass bottles for triplicate replication. Bottles rest upon platforms containing magnetic stirrers and are arranged vertically within a 1 m high and 15 cm diameter polyvinyl chloride (PVC) pipe. The pipe interior is lined with light-emitting diodes (LEDs). These LEDs produce continuous light intensities from 0&#8211;2400 &#181;mol photons m-2 s-1 of photosynthetically active radiation (PAR). Users design a custom lighting program. The light intensity can be adjusted each second or held constant for longer durations. Oxygen produced from photosynthesis exits each bottle via a one-way volumetric gas sensor. Software is used to record gas sensor data. The amount of oxygen produced can be correlated to biomass growth. If biomass samples are required, a syringe can be used to extract culture. The method is suited for microalgae grown with bicarbonate as the carbon source. These PBRs are valuable to a laboratory that requires replicated experiments, light regime flexibility, and continuous high-resolution growth data.

This publication describes the design of laboratory photobioreactors (PBRs) with customizable light regimes. The growth of cyanobacteria or microalgae, using bicarbonate as their carbon source, is monitored continuously by measuring volumetric oxygen production. These PBRs facilitate rapid, replicated laboratory growth comparisons with little user intervention during experiments.

The laboratory study of microalgae can be experimentally challenging. In addition to the cultivation requirements of non-photosynthetic microorganisms, ...

Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

Samenvatting

Meer video's verkennen