Funding by the German Environmental Foundation (DBU) is acknowledged. The authors thank Ute Kuhlicke for technical help with CLSM analysis and Birgit W&#252;rz, Rita Remer, and Jana Reichenbach for skilled experimental help. The authors would particularly like to thank Prof. Jan Roelof van der Meer and Dr. Robin Tecon for fruitful discussion and providing the bioreporter strain. It contributes to the &#8216;Chemicals in the Environment&#8217; (CITE) research program of the Helmholtz Association.

1. Preparation of Dishes, Slides and Incubation Chambers
<ol>
	<li>Prepare the following material for each microcosm: one big plastic Petri dish bottom (d&#160;=&#160;10&#160;cm), one modified (see step 1.2) small plastic Petri dish bottom (d&#160;=&#160;5&#160;cm) with lids and one counting chamber slide with three cavities.</li>
	<li>Take the desired number of Petri dish bottom parts (d&#160;=&#160;5&#160;cm). Remove part of the brim with a saw to exactly fit a slide (26&#160;mm edge length). To sterilize the system,...

<ol>
	<li>Holden, P. A., Fierer, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbial+processes+in+the+vadose+zone.">Microbial processes in the vadose zone.</a> Vadose Zone Journal. 4, 1-21 (2005).</li><li>Whitman, W. B., Coleman, D. C., Wiebe, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prokaryotes:+The+unseen+majority.">Prokaryotes: The unseen majority.</a> Proceedings of the National Academy of Sciences. 95, 6578-6583 (1998).</li><li>Kieft, T. L., 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=Microbial+abundance+and+activities+in+relation+to+water+potential+in+the+vadose+zones+of+arid+and+semiarid+sites.">Microbial abundance and activities in relation to water potential in the vadose zones of arid and semiarid sites.</a> Microbial ecology. 26, 59-78 (1993).</li><li>Wang, G., Or, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aqueous+films+limit+bacterial+cell+motility+and+colony+expansion+on+partially+saturated+rough+surfaces.">Aqueous films limit bacterial cell motility and colony expansion on partially saturated rough surfaces.</a> Environ. Microbiol. 12, 1363-1373 (2010).</li><li>Griffin, D. M., Parr, J. F., Gardner, W. R., Elliott, L. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Water Potential Relations in Soil Microbiology SSSA Special Publication. , 141-151 (1981).</li><li>Papendick, R. I., Camprell, G. S., Parr, J. F., Gardner, W. R., Elliott, L. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Water Potential Relations in Soil Microbiology SSSA Special Publication. , 1-22 (1981).</li><li>Boswell, G. P., Jacobs, H., Davidson, F. A., Gadd, G. M., Ritz, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+consequences+of+nutrient+translocation+in+mycelial+fungi.">Functional consequences of nutrient translocation in mycelial fungi.</a> J. Theor. Biol. 217, 459-477 (2002).</li><li>Jennings, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Translocation+of+solutes+in+fungi.">Translocation of solutes in fungi.</a> Biol. Rev. Camb. Philos. Soc. 62, 215-243 (1987).</li><li>Bais, H. P., Weir, T. L., Perry, L. G., Gilroy, S., Vivanco, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+root+exudates+in+rhizosphere+interactions+with+plants+and+other+organisms.">The role of root exudates in rhizosphere interactions with plants and other organisms.</a> Annu. Rev. Plant Biol. 57, 233-266 (2006).</li><li>Furuno, S., 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=Mycelia+promote+active+transport+and+spatial+dispersion+of+polycyclic+aromatic+hydrocarbons.">Mycelia promote active transport and spatial dispersion of polycyclic aromatic hydrocarbons.</a> Environ. Sci. Technol. 46, 5463-5470 (2012).</li><li>Gao, Y., Cheng, Z., Ling, W., Huang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arbuscular+mycorrhizal+fungal+hyphae+contribute+to+the+uptake+of+polycyclic+aromatic+hydrocarbons+by+plant+roots.">Arbuscular mycorrhizal fungal hyphae contribute to the uptake of polycyclic aromatic hydrocarbons by plant roots.</a> Bioresour. Technol. 101, 6895-6901 (2010).</li><li>Semple, K. T., Morriss, A. W. J., Paton, G. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioavailability+of+hydrophobic+organic+contaminants+in+soils:+fundamental+concepts+and+techniques+for+analysis.">Bioavailability of hydrophobic organic contaminants in soils: fundamental concepts and techniques for analysis.</a> Eur. J. Soil. Sci. 54, 809-818 (2003).</li><li>Tecon, R., Binggeli, O., vander Meer, 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=Double-tagged+fluorescent+bacterial+bioreporter+for+the+study+of+polycyclic+aromatic+hydrocarbon+diffusion+and+bioavailability.">Double-tagged fluorescent bacterial bioreporter for the study of polycyclic aromatic hydrocarbon diffusion and bioavailability.</a> Environ. Microbiol. 11, 2271-2283 (2009).</li><li>Tecon, R., Wells, M., vander Meer, 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=A+new+green+fluorescent+protein-based+bacterial+biosensor+for+analysing+phenanthrene+fluxes.">A new green fluorescent protein-based bacterial biosensor for analysing phenanthrene fluxes.</a> Environ. Microbiol. 8, 697-708 (2006).</li><li>Schamfuss, S., 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=Impact+of+mycelia+on+the+accessibility+of+fluorene+to+PAH-degrading+bacteria.">Impact of mycelia on the accessibility of fluorene to PAH-degrading bacteria.</a> Environ. Sci. Technol. 47, 6908-6915 (2013).</li><li>Smibert, R. M., Krieg, R. M., Gerhardt, P., Murray, R. G. E., Costilow, R. N., Nester, E. W., Wood, W. A., Krieg, N. R., Phillips, G. B., 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=.">.</a> Manual of methods for general bacteriology. 19, 409-443 (1981).</li><li>Wu, C. H., Warren, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+autofluorescence+in+fungi+and+its+correlation+with+viability.">Natural autofluorescence in fungi and its correlation with viability.</a> Mycologia. 76, 1049-1058 (1984).</li><li>Schneider, C. A., Rasband, W. S., Eliceiri, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NIH+Image+to+ImageJ:+25+years+of+image+analysis.">NIH Image to ImageJ: 25 years of image analysis.</a> Nat. Methods. 9, 671-675 (2012).</li><li>Pedersen, C., Sylvia, D., Mukerji, K. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+8+Concepts+in+Mycorrhizal+Research.">Ch. 8 Concepts in Mycorrhizal Research.</a> Handbook of Vegetation Science. Vol. 19, 195-222 (1996).</li><li>Furuno, S., 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=Fungal+mycelia+allow+chemotactic+dispersal+of+polycyclic+aromatic+hydrocarbon-degrading+bacteria+in+water-unsaturated+systems.">Fungal mycelia allow chemotactic dispersal of polycyclic aromatic hydrocarbon-degrading bacteria in water-unsaturated systems.</a> Environ. Microbiol. 12, 1391-1398 (2010).</li></ol>

The presented microcosm setup proved suitable to study bioavailability of spatially separated chemicals to degrading organisms after uptake and transport by mycelia. Potential gas-phase transport of partially volatile compounds is prevented and bacterial bioreporter cells can be visualized without elaborate sample preparation and thus with minimal disturbance of the sensitive system. At the same time, chemical analysis of the sample can be easily conducted allowing for a good control of the gained results and for quantif...

Soil is densely populated by a wide range of microorganisms1,2 such as bacteria. However, conditions in this habitat are challenging, especially in terms of water availability3. Bacteria permanently need to search for optimal conditions in heterogeneous environments4, but the absence of continuous water films is resulting in restricted mobility5 hindering them to spread freely. Also, diffusion rates of solutes (e.g., nutrients) are lowered under unsaturated conditions6. Thus, bacteria and nutrients are often physically separated and nutrient accessibility is limited3. As a consequence, a transport vector for chemical compounds which does not require a continuous water-phase could help to overcome these limitations. In fact, many microorganisms such as fungi and oomycetes have developed a filamentous growth form enabling them to grow through air-filled pore spaces thereby reaching and mobilizing also physical separated nutrients7 and carbonaceous8 substances over long distances. They may even act as biological transport vectors which deliver sugars and other energy sources to bacteria9. Uptake and transport in mycelial organisms has also been shown for hydrophobic organic pollutants such as polycyclic aromatic hydrocarbons (PAH) in Pythium ultimum10 or in arbuscular mycorrhizal fungi11. Since PAH are ubiquitous and poorly water soluble contaminants12 in soil, mycelia-mediated transport might help to increase contaminant bioavailability for potential bacterial degraders. Whereas the total amount of contaminant transport can be quantified directly by chemical means10, bioavailability of contaminants transported by mycelia to degrading bacteria and other organisms cannot be assessed easily.
The following protocol presents a method to evaluate the impact of mycelia on contaminant bioavailability to bacterial degraders in a direct manner; it allows gathering information about the spatiotemporal impact of contaminants on microbial ecosystems. We describe how to set up an elaborate unsaturated microcosm system mimicking air-water interfaces in soil by linking a physically separated PAH point source with PAH-degrading bioreporter bacteria via mycelial transport vectors. Because airborne transport is excluded, the effect of mycelial-based transport on PAH bioavailability for bacteria can be studied in an isolated way. In more detail, three-ring PAH fluorene, the mycelial organism Pythium ultimum and the bioreporter bacterium Burkholderia sartisoli RP037-mChe13 were applied in the described microcosm setups. The bacterium B. sartisoli RP037-mChe was originally constructed to study phenanthrene fluxes to the cell14 and expresses enhanced green fluorescent protein (eGFP) as a result of the PAH flux to the cell, whereas the red fluorescing mCherry is expressed constitutively. Detailed information on the reporter construction is given by Tecon et al.13 In preliminary tests, the bacterium revealed no swimming and only very slow swarming ability. It was able to migrate slowly on hyphae of Pythium ultimum when applied as a dense suspension on top of the hyphae. Since bacteria were embedded in agarose in the following protocol, migration on hyphae did not occur.
Using confocal laser scanning microscopy (CLSM), the bioreporter bacteria can be visualized directly in the microcosms and expression of eGFP can be quantified in relation to the amount of cells (proportional to the mCherry signal) with the help of the software ImageJ. This allows comparing bioavailability qualitatively in different scenarios (i.e., higher or lower). FLU was found to be bioavailable after mycelial transport by P. ultimum (i.e., it was higher than in a negative control). Furthermore, the protocol describes how to quantify the total amount of mycelia-mediated transport via chemical means and to verify contaminant bioavailability using silicon-coated glass fibers (SPME fibers) in identical microcosms. Results using this microcosm setup have been published and discussed for the combination of P. ultimum, fluorene and B. sartisoli RP037-mChe15. Here, the focus lies on a detailed method description and the identification of potential pitfalls of the protocol to provide this knowledge for potential further applications. Further applications may involve various fungal, bacterial species (e.g., from contaminated sites), and other contaminants (e.g., pesticides) or contaminant-supply (e.g., aged soils).

<table border="0" cellpadding="0" cellspacing="0" width="1158">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Name of Reagent/ Equipment</td>
			<td style="width:195px;">Company</td>
			<td style="width:128px;">Catalog Number</td>
			<td style="width:523px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Confocal Microscope</td>
			<td style="width:195px;">Leica</td>
			<td style="width:128px;"></td>
			<td>TCS SP5X, LAS AF - Version 2.6.1; or equivalent CLSM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">GC HP 7890 Series GC and Agilent 5975C MSD</td>
			<td>Agilent</td>
			<td style="width:128px;"></td>
			<td>an equivalent GC/MS may be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">GC capillary column J&#38;W 121-5522&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
			<td>Agilent</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Cork borer</td>
			<td style="width:195px;">Fisher Scientific</td>
			<td align="right">12863952</td>
			<td>or any other</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Cover slips</td>
			<td style="width:195px;">Marienfeld</td>
			<td style="width:128px;">107222</td>
			<td>High performance, No.1.5H</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">GC/MS insterts</td>
			<td style="width:195px;">WICOM</td>
			<td style="width:128px;">WIC 47080</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">GC/MS vials 2 ml</td>
			<td style="width:195px;">WICOM</td>
			<td style="width:128px;">WIC 41150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Lids / septa for screw cap vials</td>
			<td style="width:195px;">DIONEX</td>
			<td>49463 / 049464&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Lids for GC/MS vials</td>
			<td style="width:195px;">WICOM</td>
			<td style="width:128px;">WIC 43948/B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Objective Slides</td>
			<td style="width:195px;">Menzel</td>
			<td style="width:128px;"></td>
			<td>ordinary</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">PDMS coated glass fibers</td>
			<td style="width:195px;">Polymicro Technologies, Inc.</td>
			<td style="width:128px;"></td>
			<td>V (PDMS) = 13.55 &#177; 0.02 &#181;L m-1</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">Petri Dishes small / big</td>
			<td style="width:195px;">Greiner</td>
			<td style="width:128px;">633-102 / 628-102</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Screw cap vials 40 ml</td>
			<td style="width:195px;">DIONEX</td>
			<td>48783</td>
			<td>other glass vials may be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Screw cap vials 60 ml</td>
			<td style="width:195px;">DIONEX</td>
			<td>48784</td>
			<td>other glass vials may be used</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:313px;">Acenaphthylene d08</td>
			<td style="width:195px;">Dr. Ehrenstorfer</td>
			<td style="width:128px;">C 20510100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Acetone</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">9372.2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Activated carbon</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:128px;">242276-1kg</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Agarose</td>
			<td style="width:195px;">Carl Roth</td>
			<td align="right">2267.4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Fluorene</td>
			<td style="width:195px;">Fluka</td>
			<td style="width:128px;">46880</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:313px;">Kanamycin sulfate</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">T832.2</td>
			<td>50 mg L-1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Methanol</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">P7171</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Minimal Medium:</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td>100 mL solution 1 + 25 mL solution 2 + 5 mL solution 3 ad. 1000 mL aqua dest</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160; Solution 1</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:313px;">&#160;&#160;&#160; Ammonium sulfate&#160;</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">3746.1</td>
			<td>5 g L-1&#160;</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:313px;">&#160;&#160;&#160; Magnesium chloride x 6 H2O</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">2189.1</td>
			<td>1 g L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:313px;">&#160;&#160;&#160; Calcium nitrate x 4 H2O</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">P740.1</td>
			<td>0.5 g L-1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160; Solution 2</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:313px;">&#160;&#160;&#160; Disodium phosphate</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">P030.1</td>
			<td>55.83 g L-1</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:313px;">&#160;&#160;&#160; Monopotassium phosphate</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">3904.1</td>
			<td>20 g L-1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160; Solution 3</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td>pH 6.0</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">&#160;&#160;&#160; Disodium EDTA</td>
			<td style="width:195px;">MERCK</td>
			<td style="width:128px;">1084180250</td>
			<td>0.8 g L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Iron(II) chloride x 4 H2O</td>
			<td style="width:195px;">MERCK</td>
			<td style="width:128px;">1038610250</td>
			<td>0.3 g L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Cobalt(II) chloride x 6 H2O</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">T889.3</td>
			<td>4 mg L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Manganese(II) chloride x 1 H2O&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">&#160; 4320.2</td>
			<td>10 mg L-1</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">&#160;&#160;&#160; Copper(II) sulfate</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">&#160;P023.1</td>
			<td>1 mg L-1</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">&#160;&#160;&#160; Sodium molybdate x 2 H2O</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">&#160;0274.1</td>
			<td>3 mg L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Zinc chloride</td>
			<td style="width:195px;">MERCK</td>
			<td style="width:128px;">1088160250</td>
			<td>2 mg L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Lithium chloride</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">P007.1</td>
			<td>0.5 mg L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Tin(II) chloride x 2 H2O</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">4473.1</td>
			<td>0.5 mg L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Boric acid</td>
			<td style="width:195px;">Riedel-de-Haen&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
			<td style="width:128px;">11606</td>
			<td>1 mg L-1</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">&#160;&#160;&#160; Potassium bromide</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">A137.1</td>
			<td>2 mg L-1</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">&#160;&#160;&#160; Potassium iodide</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">6750.1</td>
			<td>2 mg L-1</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">&#160;&#160;&#160; Barium chloride</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">4453.1</td>
			<td>0.5 mg L-1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">MMA</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td>Minimal medium + agarose 0.2 %</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:313px;">Phenanthrene d10</td>
			<td style="width:195px;">Dr. Ehrenstorfer</td>
			<td style="width:128px;">C 20920100</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:313px;">Potato Dextrose Agar:</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td>24 g L-1 broth + bacto-agar 1.5 %; pH 6.8</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160;&#160;&#160; Potato Dextrose broth</td>
			<td>Difco/ Beckton Dickinson</td>
			<td style="width:128px;">254920</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160;&#160;&#160; Bacto-agar</td>
			<td>Difco/ Beckton Dickinson</td>
			<td align="right">214040</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Sodium acetate x 3 hydr.</td>
			<td style="width:195px;">Carl Roth</td>
			<td style="width:128px;">6779.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Sodium sulfate</td>
			<td style="width:195px;">MERCK</td>
			<td style="width:128px;">&#160;1066495000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">Toluene</td>
			<td style="width:195px;">MERCK</td>
			<td style="width:128px;">1083252500</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:313px;">mTY medium:</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td>3 g L-1 yeast extract, 5 g L-1 bacto tryptone and 50 mM NaCl</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160;&#160;&#160; Yeast extract</td>
			<td style="width:195px;">Merck</td>
			<td>1037530500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160;&#160;&#160; Tryptone</td>
			<td style="width:195px;">Serva</td>
			<td>4864702</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:313px;">&#160;&#160;&#160; Sodium chloride</td>
			<td style="width:195px;">Carl Roth</td>
			<td>3957.1</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">imageJ with logi tool plugin</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td style="width:523px;">http://rsb.info.nih.gov/ij/download.html and http://downloads.openmicroscopy.org/bio-formats/4.4.10</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">Pythium ultimum strain 67-1</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td style="width:523px;">Obtained from the lab of Dr. Christoph Keel; Department of Fundamental Microbiology, University of Lausanne, Switzerland</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:313px;">Burkholderia sartisoli RP037-mChe</td>
			<td style="width:195px;"></td>
			<td style="width:128px;"></td>
			<td style="width:523px;">Obtained from the lab of Prof. Jan Roelof van der Meer; Department of Fundamental Microbiology, University of Lausanne, Switzerland</td>
		</tr>
	</tbody>
</table>

a whole cell bioreporter approach to assess transport and bioavailability of organic contaminants in water unsaturated systems

Bioavailability of contaminants is a prerequisite for their effective biodegradation in soil. The average bulk concentration of a contaminant, however, is not an appropriate measure for its availability; bioavailability rather depends on the dynamic interplay of potential mass transfer (flux) of a compound to a microbial cell and the capacity of the latter to degrade the compound. In water-unsaturated parts of the soil, mycelia have been shown to overcome bioavailability limitations by actively transporting and mobilizing organic compounds over the range of centimeters. Whereas the extent of mycelia-based transport can be quantified easily by chemical means, verification of the contaminant-bioavailability to bacterial cells requires a biological method. Addressing this constraint, we chose the PAH fluorene (FLU) as a model compound and developed a water unsaturated model microcosm linking a spatially separated FLU point source and the FLU degrading bioreporter bacterium Burkholderia sartisoli RP037-mChe by a mycelial network of Pythium ultimum. Since the bioreporter expresses eGFP in response of the PAH flux to the cell, bacterial FLU exposure and degradation could be monitored directly in the microcosms via confocal laser scanning microscopy (CLSM). CLSM and image analyses revealed a significant increase of the eGFP expression in the presence of P. ultimum compared to controls without mycelia or FLU thus indicating FLU bioavailability to bacteria after mycelia-mediated transport. CLSM results were supported by chemical analyses in identical microcosms. The developed microcosm proved suitable to investigate contaminant bioavailability and to concomitantly visualize the involved bacteria-mycelial interactions.

The results presented here have already been published earlier15. Please refer to the article for detailed mechanistic and environmental discussion.
After image recording via CLSM, a maximum intensity projection can be conducted using the respective microscope software or ImageJ to gain a first visual impression of the sample and the controls (Figure 2). Later, the data sets may be projected differently in order to show meaningful features by specific visualization ...

Watch this Scientific Journal Video about A Whole Cell Bioreporter Approach to Assess Transport and Bioavailability of Organic Contaminants in Water Unsaturated Systems at JoVE.com

A Whole Cell Bioreporter Approach to Assess Transport and Bioavailability of Organic Contaminants in Water Unsaturated Systems

A whole cell bioreporter assay with Burkholderia sartisoli RP037-mChe was developed to detect fractions of an organic contaminant (i.e., fluorene) available for bacterial degradation after active transport by mycelia bridging air-filled pores in a water unsaturated model system.

Bioavailability of contaminants is a prerequisite for their effective biodegradation in soil. The average bulk concentration of a contaminant, however, is ...

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Research

JoVE Journal

Environment

10.3K ビュー.  Helmholtz Centre for Environmental Research - UFZ.  バークホルデリアsartisoli RP037-MCHEと全細胞バイオレポーターアッセイは、水飽和モデル系内の空気で満たされた細孔を橋渡し菌糸体により能動輸送後の細菌による分解に利用可能な有機汚染物質（ すなわち、フルオレン）の画分を検出するために開発されました。 