Support for this research was provided by USDA National Institute of Food and Agriculture Hatch Project ALA0HIGGINS and the Auburn University Offices of the Provost, the Vice President for Research, and the Samuel Ginn College of Engineering. Support was also provided by NSF grant CBET-1438211.

<ol>
	<li>Prandini, J. 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=Enhancement+of+nutrient+removal+from+swine+wastewater+digestate+coupled+to+biogas+purification+by+microalgae+Scenedesmus+spp.">Enhancement of nutrient removal from swine wastewater digestate coupled to biogas purification by microalgae Scenedesmus spp.</a> Bioresource Technology. , 67-75 (2016).</li><li>Liu, 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=Phycoremediation+of+dairy+and+winery+wastewater+using+Diplosphaera+sp.+MM1.">Phycoremediation of dairy and winery wastewater using Diplosphaera sp. MM1.</a> Journal of Applied Phycology. 28 (6), 3331-3341 (2016).</li><li>Passero, M., Cragin, B., Coats, E. R., McDonald, A. G., Feris, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dairy+Wastewaters+for+Algae+Cultivation,+Polyhydroxyalkanote+Reactor+Effluent+Versus+Anaerobic+Digester+Effluent.">Dairy Wastewaters for Algae Cultivation, Polyhydroxyalkanote Reactor Effluent Versus Anaerobic Digester Effluent.</a> BioEnergy Research. 8 (4), 1647-1660 (2015).</li><li>Hodgskiss, L. H., Nagy, J., Barnhart, E. P., Cunningham, A. B., Fields, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cultivation+of+a+native+alga+for+biomass+and+biofuel+accumulation+in+coal+bed+methane+production+water.">Cultivation of a native alga for biomass and biofuel accumulation in coal bed methane production water.</a> Algal Research. 19, 63-68 (2016).</li><li>Gao, 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=Oil+accumulation+mechanisms+of+the+oleaginous+microalga+Chlorella+protothecoides+revealed+through+its+genome,+transcriptomes,+and+proteomes.">Oil accumulation mechanisms of the oleaginous microalga Chlorella protothecoides revealed through its genome, transcriptomes, and proteomes.</a> BMC Genomics. 15, (2014).</li><li>Burch, A. R., Franz, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combined+nitrogen+limitation+and+hydrogen+peroxide+treatment+enhances+neutral+lipid+accumulation+in+the+marine+diatom+Phaeodactylum+tricornutum.">Combined nitrogen limitation and hydrogen peroxide treatment enhances neutral lipid accumulation in the marine diatom Phaeodactylum tricornutum.</a> Bioresource Technology. 219, 559-565 (2016).</li><li>Brennan, L., Owende, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofuels+from+microalgae--A+review+of+technologies+for+production,+processing,+and+extractions+of+biofuels+and+co-products.">Biofuels from microalgae--A review of technologies for production, processing, and extractions of biofuels and co-products.</a> Renewable Sustainable Energy Reviews. 14 (2), 557-577 (2009).</li><li>Branyikova, I., 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=Microalgae+-+Novel+highly+efficient+starch+producers.">Microalgae - Novel highly efficient starch producers.</a> Biotechnology and Bioengineering. 108 (4), 766-776 (2010).</li><li>Chalima, 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=Utilization+of+Volatile+Fatty+Acids+from+Microalgae+for+the+Production+of+High+Added+Value+Compounds.">Utilization of Volatile Fatty Acids from Microalgae for the Production of High Added Value Compounds.</a> Fermentation. 3 (4), (2017).</li><li>Harun, R., Singh, M., Forde, G. M., Danquah, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioprocess+engineering+of+microalgae+to+produce+a+variety+of+consumer+products.">Bioprocess engineering of microalgae to produce a variety of consumer products.</a> Renewable and Sustainable Energy Reviews. 14 (3), 1037-1047 (2010).</li><li>Liu, 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=Development+of+a+new+method+for+genetic+transformation+of+the+green+alga+Chlorella+ellipsoidea.">Development of a new method for genetic transformation of the green alga Chlorella ellipsoidea.</a> Molecular biotechnology. 54 (2), 211-219 (2013).</li><li>Cheng, J., 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=Mutate+Chlorella+sp.+by+nuclear+irradiation+to+fix+high+concentrations+of+CO2.">Mutate Chlorella sp. by nuclear irradiation to fix high concentrations of CO2.</a> Bioresource Technology. 136, 496-501 (2013).</li><li>Davis, R., Aden, A., Pienkos, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Techno-economic+analysis+of+autotrophic+microalgae+for+fuel+production.">Techno-economic analysis of autotrophic microalgae for fuel production.</a> Applied Energy. 88 (10), 3524-3531 (2011).</li><li>Sales, C. M., Au, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+Scale+in+a+Photosynthetic+Reactor+System+for+Algal+Remediation+of+Wastewater.">Comparison of Scale in a Photosynthetic Reactor System for Algal Remediation of Wastewater.</a> Journal of Visualized Experiments. (121), e55256 (2017).</li><li>Higgins, B. T., 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=Cofactor+symbiosis+for+enhanced+algal+growth,+biofuel+production,+and+wastewater+treatment.">Cofactor symbiosis for enhanced algal growth, biofuel production, and wastewater treatment.</a> Algal Research. 17, 308-315 (2016).</li><li>Higgins, 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=Algal-bacterial+synergy+in+treatment+of+winery+wastewater.">Algal-bacterial synergy in treatment of winery wastewater.</a> Nature Clean Water. 1 (6), (2017).</li><li>Higgins, B. T., 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+thiamine+metabolites+and+spent+medium+from+Chlorella+sorokiniana+on+metabolism+in+the+green+algae+Auxenochlorella+prototheciodes.">Impact of thiamine metabolites and spent medium from Chlorella sorokiniana on metabolism in the green algae Auxenochlorella prototheciodes.</a> Algal Research. 33, 197-208 (2018).</li><li>L&#233;pinay, 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=First+insight+on+interactions+between+bacteria+and+the+marine+diatom+Haslea+ostrearia:+Algal+growth+and+metabolomic+fingerprinting.">First insight on interactions between bacteria and the marine diatom Haslea ostrearia: Algal growth and metabolomic fingerprinting.</a> Algal Research. 31, 395-405 (2018).</li><li>Franchino, M., Comino, E., Bona, F., Riggio, V. 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+of+three+microalgae+strains+and+nutrient+removal+from+an+agro-zootechnical+digestate.">Growth of three microalgae strains and nutrient removal from an agro-zootechnical digestate.</a> Chemosphere. 92 (6), 738-744 (2013).</li><li>Choix, F. J., Lopez-Cisneros, C. G., Mendez-Acosta, H. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Azospirillum+brasilense+Increases+CO2+Fixation+on+Microalgae+Scenedesmus+obliquus,+Chlorella+vulgaris,+and+Chlamydomonas+reinhardtii+Cultured+on+High+CO2+Concentrations.">Azospirillum brasilense Increases CO2 Fixation on Microalgae Scenedesmus obliquus, Chlorella vulgaris, and Chlamydomonas reinhardtii Cultured on High CO2 Concentrations.</a> Microbial Ecology. 76 (2), 430-442 (2018).</li><li>Higgins, B., VanderGheynst, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Escherichia+coli+on+mixotrophic+growth+of+Chlorella+minutissima+and+production+of+biofuel+precursors.">Effects of Escherichia coli on mixotrophic growth of Chlorella minutissima and production of biofuel precursors.</a> PLoS One. 9 (5), e96807 (2014).</li><li>Higgins, B., Thornton-Dunwoody, A., Labavitch, J. M., VanderGheynst, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microplate+assay+for+quantitation+of+neutral+lipids+in+extracts+from+microalgae.">Microplate assay for quantitation of neutral lipids in extracts from microalgae.</a> Analytical Biochemistry. 465, 81-89 (2014).</li><li>Tanadul, O. U., Vandergheynst, J. S., Beckles, D. M., Powell, A. L., Labavitch, 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+impact+of+elevated+CO2+concentration+on+the+quality+of+algal+starch+as+a+potential+biofuel+feedstock.">The impact of elevated CO2 concentration on the quality of algal starch as a potential biofuel feedstock.</a> Biotechnology and Bioengineering. 111 (7), 1323-1331 (2014).</li><li>Folch, J., Lees, M., Sloane Stanley, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+method+for+the+isolation+and+purification+of+total+lipides+from+animal+tissues.">A simple method for the isolation and purification of total lipides from animal tissues.</a> Journal of Biological Chemistry. 226 (1), 497-509 (1957).</li><li>Higgins, B. T., 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=Informatics+for+improved+algal+taxonomic+classification+and+research:+A+case+study+of+UTEX+2341.">Informatics for improved algal taxonomic classification and research: A case study of UTEX 2341.</a> Algal Research. 12, 545-549 (2015).</li><li>Garrett, R. H., Grisham, 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> Biochemistry. , 578-730 (2012).</li><li>de-Bashan, L. E., Trejo, A., Huss, V. A. R., Hernandez, J. -. P., Bashan, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chlorella+sorokiniana+UTEX+2805,+a+heat+and+intense,+sunlight-tolerant+microalga+with+potential+for+removing+ammonium+from+wastewater.">Chlorella sorokiniana UTEX 2805, a heat and intense, sunlight-tolerant microalga with potential for removing ammonium from wastewater.</a> Bioresource Technology. 99 (11), 4980-4989 (2008).</li><li>Wang, Q., Higgins, B., Ji, H., Zhao, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Annual International Meeting of the ASABE. , (2018).</li></ol>

The authors have nothing to disclose.

The most important consideration when culturing algae is an understanding of the specific needs of the organism or group of organisms. The algae cultivation system described here can be used to culture a wide range of algae but the specific abiotic factors (temperature, media, pH, light intensity, CO2 level, aeration rate) need to be adjusted to the needs of the organism. Note the parameters described here were used for the cultivation of Chlorella and Auxenochlorella. These organisms are of ...

The application of microalgae in engineering and biotechnology has attracted great interest in recent years. Microalgae are being studied for use in wastewater treatment1,2,3,4, biofuel production5,6,7,8, and the production of nutraceuticals and other high value products9,10. Algae are also being genetically modified at greater rates in an effort to improve their fitness for specific engineering applications11,12. Consequently, there is great interest in experimentation with industrially relevant organisms in controlled settings. The purpose of this method is to communicate an effective approach to culture microalgae in a controlled laboratory environment, and to measure the growth and neutral lipid content of that algae. Improving growth rates and neutral lipid content of microalgae have been identified as two key bottlenecks toward commercialization of algal biofuels13.
A wide range of approaches have been used to culture algae for experimental purposes. In general, these approaches can be divided between large-scale outdoor cultivation and small-scale indoor cultivation. Outdoor cultivation in photobioreactors and open ponds is appropriate for experimentation aimed at scaling up processes that have already been proven at laboratory scale (e.g., to test scale-up of a new high-lipid strain of algae)14. However, indoor small-scale cultivation is appropriate when developing new or improved algae strains or performing experiments aimed at understanding biological mechanisms. In these latter cases, a high-degree of experimental control is required to tease out subtle changes in biological behavior. To that end, axenic cultures are often required in order to minimize the complex biotic factors associated with other organisms (e.g. bacteria, other algae) that inevitably grow in large-scale outdoor systems. Even when studying interactions among algae and other organisms, we have found that use of highly-controlled experimental conditions is helpful when examining molecular exchange among organisms15,16,17.
Within the category of small-scale indoor algae cultivation, a range of approaches have been used. Perhaps the most common approach is to grow algae in Erlenmeyer flasks on a shaker table beneath a light bank18,19. Exchange of oxygen and CO2 takes place by passive diffusion through a foam plug in the top of the flask. Some researchers have improved this set-up through active aeration of the flasks20. Another approach is to cultivate algae in bottles, mixed by stir bar and active aeration. Despite their simplicity, we have found that the use of flasks and bottles often leads to inconsistent results among biological replicates. Presumably this is due to position effects - different positions receive different amounts of light, which also affect internal reactor temperatures. Daily rotation of reactors to new positions can help but does not alleviate the problem because certain stages of algae growth (e.g., early exponential) are more sensitive to positional effects than others (e.g., log phase).
On the opposite side of the spectrum of technological sophistication are fully-controlled commercial photobioreactors. These systems continuously monitor and adjust conditions in the reactor to optimize algae growth. They have programmable lighting, real-time temperature control, and pH control. Unfortunately, they are expensive and typically cost several thousand dollars per reactor. Most scientific and engineering journals require biological replication of results, necessitating the purchase of multiple bioreactors. We present here a bubble column reactor system that bridges the divide between the simple (flask) and sophisticated (fully-controlled bioreactor) approaches for lab-scale algae cultivation. Bubble columns use rising gas bubbles to facilitate gas exchange and mix the reactor. This approach provides some degree of control over the lighting and temperature but does so in a way that is cost-effective. Moreover, we have found this system to yield highly consistent results among biological replicates, reducing the required number of biological replicates needed in order to obtain statistically significant results when compared to the flask or bottle approach. We have also used this system to successfully cultivate mixtures of algae and bacteria21. In addition to algae cultivation, we outline a procedure for measuring the neutral lipid content in the cultured algae. The latter method has been published elsewhere22, but we include the procedure here to provide step-by-step instructions for how to employ it successfully.

<table>
	<tbody>
		<tr>
			<td>Supplies for airlift photobioreactor setup</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1 L Pyrex bottles</td>
			<td>Corning</td>
			<td>16157-191</td>
			<td>For bottle reactors, humidifiers</td>
		</tr>
		<tr>
			<td>1/2&#34; hose clamp</td>
			<td>Home Depot</td>
			<td>UC953A</td>
			<td>or equivalent</td>
		</tr>
		<tr>
			<td>1/4&#34; female luer to barb</td>
			<td>Nordson biomedical</td>
			<td>Nordson FTLL360-6005</td>
			<td>1/4&#34; ID, PP</td>
		</tr>
		<tr>
			<td>1/4&#34; ID, 3/8&#34; OD autoclaveable PVC tubing</td>
			<td>Thermo-Nalgene</td>
			<td>63013-244</td>
			<td>50&#39;</td>
		</tr>
		<tr>
			<td>1/4&#34; in O-rings</td>
			<td>Grainger</td>
			<td>1REC5</td>
			<td>#010 Medium Hard Silicone O-Ring, 0.239&#34; I.D., 0.379&#34;O.D.</td>
		</tr>
		<tr>
			<td>1/8&#34; Female luer to barb</td>
			<td>Nordson biomedical</td>
			<td>FTLL230-6005</td>
			<td></td>
		</tr>
		<tr>
			<td>1/8&#34; ID, 1/4&#34; OD autoclaveable PVC tubing</td>
			<td>Thermo-Nalgene</td>
			<td>63013-608</td>
			<td>250&#39;</td>
		</tr>
		<tr>
			<td>1/8&#34; male spinning luer to barb</td>
			<td>Nordson biomedical</td>
			<td>MLRL013-6005</td>
			<td></td>
		</tr>
		<tr>
			<td>1/8&#34; multiport barb</td>
			<td>Nordson biomedical</td>
			<td>4PLL230-6005</td>
			<td>1/8&#34; multiport barb</td>
		</tr>
		<tr>
			<td>1/8&#34; NPT to barb</td>
			<td>Nordson biomedical</td>
			<td>18230-6005</td>
			<td>1/8&#34; 200 series barb</td>
		</tr>
		<tr>
			<td>1/8&#34; panel mount luer</td>
			<td>Nordson biomedical</td>
			<td>Nordson MLRLB230-6005</td>
			<td>1/8&#34;, PP</td>
		</tr>
		<tr>
			<td>10 gallon fish tank</td>
			<td>Walmart</td>
			<td>802262</td>
			<td>Can hold up to 8 bioreactors depending on layout</td>
		</tr>
		<tr>
			<td>100-1000 ccm flow meter</td>
			<td>Dwyer</td>
			<td>RMA-13-SSV</td>
			<td>For bottle reactors</td>
		</tr>
		<tr>
			<td>2 ft fluorescent light bank</td>
			<td>Agrobrite</td>
			<td>FLT24 T5</td>
			<td></td>
		</tr>
		<tr>
			<td>200-2500 ccm flow meter</td>
			<td>Dwyer</td>
			<td>RMA-14-SSV</td>
			<td>For air regulation upstream of humidifier</td>
		</tr>
		<tr>
			<td>250 mL Pyrex bottles</td>
			<td>Corning</td>
			<td>16157-136</td>
			<td>For gas mixing after humidifier</td>
		</tr>
		<tr>
			<td>50-500 ccm flow meter</td>
			<td>Dwyer</td>
			<td>RMA-12-SSV</td>
			<td>For hybridization tube reactors</td>
		</tr>
		<tr>
			<td>5-50 ccm flow meter</td>
			<td>Dwyer</td>
			<td>RMA-151-SSV</td>
			<td>For CO2 flow rate control</td>
		</tr>
		<tr>
			<td>Air filters 0.2 &#181;m</td>
			<td>Whatman/ Fisher</td>
			<td>09-745-1A</td>
			<td>Polyvent, 28 mm, 0.2 &#181;m, PTFE, 50 pack</td>
		</tr>
		<tr>
			<td>Check valves</td>
			<td>VWR</td>
			<td>89094-714</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning lids for pyrex bottles</td>
			<td>VWR</td>
			<td>89000-233</td>
			<td>10 GL45 lids</td>
		</tr>
		<tr>
			<td>Female luer endcap</td>
			<td>Nordson biomedical</td>
			<td>Nordson FTLLP-6005</td>
			<td>Female stable PP</td>
		</tr>
		<tr>
			<td>Hybridization tubes</td>
			<td>Corning</td>
			<td>32645-030</td>
			<td>35x300 mm, pack of 2</td>
		</tr>
		<tr>
			<td>Light timer</td>
			<td>Walmart</td>
			<td>556393626</td>
			<td></td>
		</tr>
		<tr>
			<td>Locknuts</td>
			<td>Nordson biomedical</td>
			<td>Nordson LNS-3</td>
			<td>1/4&#34;, red nylon</td>
		</tr>
		<tr>
			<td>Low profile magnetic stirrer</td>
			<td>VWR</td>
			<td>10153-690</td>
			<td>Low profile magnetic stirrer</td>
		</tr>
		<tr>
			<td>Male luer endcap</td>
			<td>Nordson biomedical</td>
			<td>Nordson LP4-6005</td>
			<td>Male plug PP</td>
		</tr>
		<tr>
			<td>Spinning luer lock ring</td>
			<td>Nordson biomedical</td>
			<td>Nordson FSLLR-6005</td>
			<td></td>
		</tr>
		<tr>
			<td>Stir bars - long</td>
			<td>VWR</td>
			<td>58949-040</td>
			<td>38.1 mm, for bottle reactors</td>
		</tr>
		<tr>
			<td>Stir bars - medium</td>
			<td>VWR</td>
			<td>58949-034</td>
			<td>25 mm, for hyridization tubes</td>
		</tr>
		<tr>
			<td>Supplies and reagents for culturing algae</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0.2 &#181;m filters</td>
			<td>VWR</td>
			<td>28145-491</td>
			<td>13 mm, PTFE, for filtering spent media from daily culture sampling</td>
		</tr>
		<tr>
			<td>1 mL syringes</td>
			<td>Air-tite</td>
			<td>89215-216</td>
			<td>For filtering spent media from daily culture sampling</td>
		</tr>
		<tr>
			<td>1.5 mL tubes</td>
			<td>VWR</td>
			<td>87003-294</td>
			<td>Sterile (or equivalent)</td>
		</tr>
		<tr>
			<td>10 mL Serological pipettes</td>
			<td>Greiner Bio-One</td>
			<td>82050-482</td>
			<td>Sterile (or equivalent)</td>
		</tr>
		<tr>
			<td>100 mm plates</td>
			<td>VWR</td>
			<td>25384-342</td>
			<td>100x15 mm stackable petri dishes, sterile</td>
		</tr>
		<tr>
			<td>15 mL tubes</td>
			<td>Greiner Bio-One</td>
			<td>82050-276</td>
			<td>Sterile (or equivalent), polypropylene</td>
		</tr>
		<tr>
			<td>2 mL Serological pipette tips</td>
			<td>Greiner Bio-One</td>
			<td>82051-584</td>
			<td>Sterile (or equivalent)</td>
		</tr>
		<tr>
			<td>2 mL tubes</td>
			<td>VWR</td>
			<td>87003-298</td>
			<td>Sterile (or equivalent)</td>
		</tr>
		<tr>
			<td>50 mL tubes</td>
			<td>Greiner Bio-One</td>
			<td>82050-348</td>
			<td>Sterile (or equivalent), polypropylene</td>
		</tr>
		<tr>
			<td>96 well microplate</td>
			<td>Greiner Bio-One</td>
			<td>89089-578</td>
			<td>Polystyrene with lid, flat bottom</td>
		</tr>
		<tr>
			<td>Inocculating loops</td>
			<td>VWR</td>
			<td>80094-478</td>
			<td>Sterile (or equivalent)</td>
		</tr>
		<tr>
			<td>Liquid carbon dioxide tank and regulator</td>
			<td>Airgas</td>
			<td>CD-50</td>
			<td></td>
		</tr>
		<tr>
			<td>Supplies and reagents for lipid extraction and neutral lipid assay</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2 mL bead tubes</td>
			<td>VWR</td>
			<td>10158-556</td>
			<td>Polypropylene tube w/ lid</td>
		</tr>
		<tr>
			<td>96 well microplates</td>
			<td>Greiner Bio-One</td>
			<td>82050-774</td>
			<td>Polypropylene, flat bottom</td>
		</tr>
		<tr>
			<td>Bleach</td>
			<td>Walmart</td>
			<td>550646751</td>
			<td>Only use regular bleach, not cleaning bleach</td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>BDH</td>
			<td>BDH1109-4LG</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide</td>
			<td>BDH</td>
			<td>BDH1115-1LP</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl alcohol</td>
			<td>BDH</td>
			<td>BDH1133-1LP</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>BDH</td>
			<td>BDH20864.400</td>
			<td></td>
		</tr>
		<tr>
			<td>Nile red</td>
			<td>VWR</td>
			<td>TCN0659-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Pasteur pipette tips</td>
			<td>VWR</td>
			<td>14673-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>BDH</td>
			<td>BDH9286-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Vegetable oil</td>
			<td>Walmart</td>
			<td>9276383</td>
			<td>Any vegetable oil should work as long as it is fresh</td>
		</tr>
		<tr>
			<td>Zirconia/ silica beads (0.5 mm diameter)</td>
			<td>Biospec products</td>
			<td>11079105z</td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Analytical balance</td>
			<td>Mettler-Toledo</td>
			<td>XS205DU</td>
			<td>Capable of at least 4 decimal accuracy</td>
		</tr>
		<tr>
			<td>Bead homogenizer</td>
			<td>Omni</td>
			<td>19-040E</td>
			<td></td>
		</tr>
		<tr>
			<td>Benchtop micro centrifuge</td>
			<td>Thermo</td>
			<td>Heraeus Fresco 21 with 24x2</td>
			<td>Including rotor capable of handling 1.5 and 2 mL tubes</td>
		</tr>
		<tr>
			<td>Dry block heater</td>
			<td>VWR</td>
			<td>75838-282</td>
			<td>Including dry block for a microplate</td>
		</tr>
		<tr>
			<td>Freeze dryer</td>
			<td>Labconco</td>
			<td>7670520</td>
			<td>2.5L freeze drying system</td>
		</tr>
		<tr>
			<td>Large benchtop centrifuge</td>
			<td>Thermo</td>
			<td>Heraeus Megafuge 16R Tissue</td>
			<td>Including rotors capable of handling 400 mL bottles, 50 mL tubes, and 15 mL tubes</td>
		</tr>
		<tr>
			<td>Microplate reader</td>
			<td>Molecular Devices</td>
			<td>SpectraMax M2</td>
			<td>Capable of reading absorbance and fluorescence</td>
		</tr>
		<tr>
			<td>Vortex mixer</td>
			<td>VWR</td>
			<td>10153-838</td>
			<td></td>
		</tr>
	</tbody>
</table>

cultivation of green microalgae in bubble column photobioreactors and an assay for neutral lipids

There is significant interest in the study of microalgae for engineering applications such as the production of biofuels, high value products, and for the treatment of wastes. As most new research efforts begin at laboratory scale, there is a need for cost-effective methods for culturing microalgae in a reproducible manner. Here, we communicate an effective approach to culture microalgae in laboratory-scale photobioreactors, and to measure the growth and neutral lipid content of that algae. Instructions are also included on how to set up the photobioreactor system. Although the example organisms are species of Chlorella and Auxenochlorella, this system can be adapted to cultivate a wide range of microalgae, including co-cultures of algae with non-algae species. Stock cultures are first grown in bottles to produce inoculum for the photobioreactor system. Algae inoculum is concentrated and transferred to photobioreactors for cultivation in batch mode. Samples are collected daily for the optical density readings. At the end of the batch culture, cells are harvested by centrifuge, washed, and freeze dried to obtain a final dry weight concentration. The final dry weight concentration is used to create a correlation between the optical density and the dry weight concentration. A modified Folch method is subsequently used to extract total lipids from the freeze-dried biomass and the extract is assayed for its neutral lipid content using a microplate assay. This assay has been published previously but protocol steps were included here to highlight critical steps in the procedure where errors frequently occur. The bioreactor system described here fills a niche between simple flask cultivation and fully-controlled commercial bioreactors. Even with only 3-4 biological replicates per treatment, our approach to culturing algae leads to tight standard deviations in the growth and lipid assays.

This procedure yields a time course of algal optical density data at OD 550 nm (Figure 4A). The optical density and dry weight concentration data can be correlated (Figure 4B). This is accomplished by first calculating the final dry weight algae concentration after the freeze-drying step. Next, the optical density of the culture serial dilution (performed on the last day of sampling) and the actual dry weight concentrations can b...

Watch this Scientific Journal Video about Cultivation of Green Microalgae in Bubble Column Photobioreactors and an Assay for Neutral Lipids at JoVE.com

Cultivation of Green Microalgae in Bubble Column Photobioreactors and an Assay for Neutral Lipids

Here, we present a protocol to construct lab-scale bubble column photobioreactors and use them to culture microalgae. It also provides a method for the determination of the culture growth rate and neutral lipid content.

There is significant interest in the study of microalgae for engineering applications such as the production of biofuels, high value products, and for the ...

cultivation-green-microalgae-bubble-column-photobioreactors-an-assay

Research

JoVE Journal

Environment

20.7K Views.  Auburn University. Here, we present a protocol to construct lab-scale bubble column photobioreactors and use them to culture microalgae. It also provides a method for the determination of the culture growth rate and neutral lipid content.

Video: Cultivation of Green Microalgae in Bubble Column Photobioreactors and an Assay for Neutral Lipids

Analysis of Fatty Acid Content and Composition in Microalgae

A method to determine the content and composition of total fatty acids present in microalgae is described. Fatty acids are a major constituent of microalgal biomass. These fatty acids can be present in different acyl-lipid classes. Especially the fatty acids present in triacylglycerol (TAG) are of commercial interest, because they can be used for production of transportation fuels, bulk chemicals, nutraceuticals (&omega;-3 fatty acids), and food commodities. To develop commercial applications, reliable analytical methods for quantification of fatty acid content and composition are needed. Microalgae are single cells surrounded by a rigid cell wall. A fatty acid analysis method should provide sufficient cell disruption to liberate all acyl lipids and the extraction procedure used should be able to extract all acyl lipid classes.
With the method presented here all fatty acids present in microalgae can be accurately and reproducibly identified and quantified using small amounts of sample (5 mg) independent of their chain length, degree of unsaturation, or the lipid class they are part of.
This method does not provide information about the relative abundance of different lipid classes, but can be extended to separate lipid classes from each other.
The method is based on a sequence of mechanical cell disruption, solvent based lipid extraction, transesterification of fatty acids to fatty acid methyl esters (FAMEs), and quantification and identification of FAMEs using gas chromatography (GC-FID). A TAG internal standard (tripentadecanoin) is added prior to the analytical procedure to correct for losses during extraction and incomplete transesterification.

A method for the determination of fatty acid content and composition in microalgae based on mechanical cell disruption, solvent based lipid extraction, transesterification, and quantification and identification of fatty acids using gas chromatography is described. A tripentadecanoin internal standard is used to compensate for the possible losses during extraction and incomplete transesterification.

A method to determine the content and composition of total fatty acids present in microalgae is described. Fatty acids are a major constituent of ...

Optimize Flue Gas Settings to Promote Microalgae Growth in Photobioreactors via Computer Simulations

Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions1. Microalgae not only capture solar energy more efficiently than plants3, but also synthesize advanced biofuels2-4. Generally, atmospheric CO2 is not a sufficient source for supporting maximal algal growth5. On the other hand, the high concentrations of CO2 in industrial exhaust gases have adverse effects on algal physiology. Consequently, both cultivation conditions (such as nutrients and light) and the control of the flue gas flow into the photo-bioreactors are important to develop an efficient &ldquo;flue gas to algae&rdquo; system. Researchers have proposed different photobioreactor configurations4,6 and cultivation strategies7,8 with flue gas. Here, we present a protocol that demonstrates how to use models to predict the microalgal growth in response to flue gas settings. We perform both experimental illustration and model simulations to determine the favorable conditions for algal growth with flue gas. We develop a Monod-based model coupled with mass transfer and light intensity equations to simulate the microalgal growth in a homogenous photo-bioreactor. The model simulation compares algal growth and flue gas consumptions under different flue-gas settings. The model illustrates: 1) how algal growth is influenced by different volumetric mass transfer coefficients of CO2; 2) how we can find optimal CO2 concentration for algal growth via the dynamic optimization approach (DOA); 3) how we can design a rectangular on-off flue gas pulse to promote algal biomass growth and to reduce the usage of flue gas. On the experimental side, we present a protocol for growing Chlorella under the flue gas (generated by natural gas combustion). The experimental results qualitatively validate the model predictions that the high frequency flue gas pulses can significantly improve algal cultivation.

Flue gas from power plants is a cheap CO2 source for algal growth. We have built prototype &#34;flue gas to algal cultivation&#34; systems and described how to scale up the algal cultivation process. We have demonstrated the use of a mass-transfer bio-reaction model to simulate and to design the optimal operation of flue gas for the growth of Chlorella sp. in algal photo-bioreactors.

Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions1. Microalgae not only capture solar energy more efficiently ...

Transcript and Metabolite Profiling for the Evaluation of Tobacco Tree and Poplar as Feedstock for the Bio-based Industry

The global demand for food, feed, energy, and water poses extraordinary challenges for future generations. It is evident that robust platforms for the exploration of renewable resources are necessary to overcome these challenges. Within the multinational framework MultiBioPro we are developing biorefinery pipelines to maximize the use of plant biomass. More specifically, we use poplar and tobacco tree (Nicotiana glauca) as target crop species for improving saccharification, isoprenoid, long chain hydrocarbon contents, fiber quality, and suberin and lignin contents. The methods used to obtain these outputs include GC-MS, LC-MS and RNA sequencing platforms. The metabolite pipelines are well established tools to generate these types of data, but also have the limitations in that only well characterized metabolites can be used. The deep sequencing will allow us to include all transcripts present during the developmental stages of the tobacco tree leaf, but has to be mapped back to the sequence of Nicotiana tabacum. With these set-ups, we aim at a basic understanding for underlying processes and at establishing an industrial framework to exploit the outcomes. In a more long term perspective, we believe that data generated here will provide means for a sustainable biorefinery process using poplar and tobacco tree as raw material. To date the basal level of metabolites in the samples have been analyzed and the protocols utilized are provided in this article.

Plant biomass offers a renewable resource for multiple products, including fuel, feed, food, and a variety of materials. In this paper we investigate the properties of tobacco tree (Nicotiana glauca) and poplar as suitable sources for a biorefinery pipeline.

The global demand for food, feed, energy, and water poses extraordinary challenges for future generations. It is evident that robust platforms for the ...

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 ...

Measuring and Mapping Patterns of Soil Erosion and Deposition Related to Soil Carbonate Concentrations Under Agricultural Management

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonate (CaCO3) profiles. The objective is to describe a simple conceptual model and detailed protocol for repeatable field and laboratory measurements of these quantities. Here, accurate elevation is measured using a ground-based differential global positioning system (GPS); other data acquisition methods could be applied to the same basic method. Soil samples are collected from prescribed depth intervals and analyzed in the lab using an efficient and precise modified pressure-calcimeter method for quantitative analysis of inorganic carbon concentration. Standard statistical methods are applied to point data, and representative results show significant correlations between changes in soil surface layer CaCO3 and changes in elevation consistent with the conceptual model; CaCO3 generally decreased in depositional areas and increased in erosional areas. Maps are derived from point measurements of elevation and soil CaCO3 to aid analyses. A map of erosional and depositional patterns at the study site, a rain-fed winter wheat field cropped in alternating wheat-fallow strips, shows the interacting effects of water and wind erosion affected by management and topography. Alternative sampling methods and depth intervals are discussed and recommended for future work relating soil erosion and deposition to soil CaCO3.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonates. Repeatable methods for field and laboratory measurements of these quantities and data analysis methods are described here.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes ...

Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA

Traditional methods of identifying fungal exposures in occupational environments, such as culture and microscopy-based approaches, have several limitations that have resulted in the exclusion of many species. Advances in the field over the last two decades have led occupational health researchers to turn to molecular-based approaches for identifying fungal hazards. These methods have resulted in the detection of many species within indoor and occupational environments that have not been detected using traditional methods. This protocol details an approach for determining fungal diversity within air samples through genomic DNA extraction, amplification, sequencing, and taxonomic identification of fungal internal transcribed spacer (ITS) regions. ITS sequencing results in the detection of many fungal species that are either not detected or difficult to identify to species level using culture or microscopy. While these methods do not provide quantitative measures of fungal burden, they offer a new approach to hazard identification and can be used to determine overall species richness and diversity within an occupational environment.

Determining the fungal diversity within an environment is a method utilized in occupational health studies to identify health hazards. This protocol describes DNA extraction from occupational air samples for amplification and sequencing of fungal ITS regions. This approach detects many fungal species that can be overlooked by traditional assessment methods.

Traditional methods of identifying fungal exposures in occupational environments, such as culture and microscopy-based approaches, have several ...

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current measures to combat such pathogens have proved too conservative and, thus, not sufficiently effective, and they can potentially pose environmental risks. Therefore, it is extremely necessary to identify host-resistance factors to assist in controlling plant diseases naturally through the identification of resistant germplasm, the isolation and characterization of resistance genes, and the molecular breeding of resistant cultivars. In this regard, there is need to establish an accurate, rapid, and large-scale inoculation method to breed and develop plant resistance genes. The rice blast fungal pathogen Magnaporthe grisea causes severe disease symptoms and yield losses. Recently, M. grisea has emerged as a model organism for studying the mechanisms of plant-fungal pathogen interactions. Hence, we report the development of a plant virulence test method that is specific for M. grisea. This method provides for both spray inoculation with a conidial suspension and wounding inoculation with mycelium cubes or droplets of conidial suspension. The key step of the wounding inoculation method for detached rice leaves is to make wounds on plant leaves, which avoids any interference caused by host penetration resistance. This spray/wounding protocol contributes to the rapid, accurate, and large-scale screening of the pathotypes of M. grisea isolates. This integrated and systematic plant infection method will serve as an excellent starting point for gaining a broad perspective of issues in plant pathology.

The Plant Infection Test: Spray and Wound-Mediated Inoculation with the Plant Pathogen Magnaporthe Grisea

Here, we present a protocol to test plant virulence with the plant pathogen Magnaporthe grisea. This report will contribute to the large-scale screening of the pathotypes of fungi isolates and serve as an excellent starting point for understanding the resistant mechanisms of plants during molecular breeding.

Plants possess a powerful system to defend themselves against potential threats by pathogenic fungi. For agriculturally important plants, however, current ...

An Anaerobic Biosensor Assay for the Detection of Mercury and Cadmium

Mercury (Hg) bioavailability to microbes is a key step to toxic Hg biomagnification in food webs. Cadmium (Cd) transformations and bioavailability to bacteria control the amount that will accumulate in staple food crops. The bioavailability of these metals is dependent on their speciation in solution, but more particularly under anoxic conditions where Hg is methylated to toxic monomethylmercury (MeHg) and Cd persists in the rhizosphere. Whole-cell microbial biosensors give a quantifiable signal when a metal enters the cytosol and therefore are useful tools to assess metal bioavailability. Unfortunately, most biosensing efforts have so far been constrained to oxic environments due to the limited ability of existing reporter proteins to function in the absence of oxygen. In this study, we present our effort to develop and optimize a whole-cell biosensor assay capable of functioning anaerobically that can detect metals under anoxic condition in quasi-real time and within hours. We describe how the biosensor can help assess how chemical variables relevant to the environmental cycling of metals affect their bioavailability. The following protocol includes methods to (1) prepare Hg and Cd standards under anoxic conditions, (2) prepare the biosensor in the absence of oxygen, (3) design and execute an experiment to determine how a series of variable affects Hg or Cd bioavailability, and (4) to quantify and interpret biosensor data. We show the linear ranges of the biosensors and provide examples showing the method's ability to distinguish between metal bioavailability and toxicity by utilizing both metal-inducible and constitutive strains.

Here, we present a protocol to use an anaerobic whole-cell microbial biosensor to evaluate how different environmental variables affect the bioavailability of Hg and Cd to bacteria in anoxic environments.

Mercury (Hg) bioavailability to microbes is a key step to toxic Hg biomagnification in food webs. Cadmium (Cd) transformations and bioavailability to ...

Detection of Tilapia Lake Virus Using Conventional RT-PCR and SYBR Green RT-qPCR

The aim of this method is to facilitate the fast, sensitive and specific detection of Tilapia Lake Virus (TiLV) in tilapia tissues. This protocol can be used as part of surveillance programs, biosecurity measures and in TiLV basic research laboratories. The gold standard of virus diagnostics typically involves virus isolation followed by complementary techniques such as reverse-transcription polymerase chain reaction (RT-PCR) for further verification. This can be cumbersome, time-consuming and typically requires tissue samples heavily infected with virus. The use of RT-quantitative (q)PCR in the detection of viruses is advantageous because of its quantitative nature, high sensitivity, specificity, scalability and its rapid time to result. Here, the entire method of PCR based approaches for TiLV detection is described, from tilapia organ sectioning, total ribonucleic acid (RNA) extraction using a guanidium thiocyanate-phenol-chloroform solution, RNA quantification, followed by a two-step PCR protocol entailing, complementary deoxyribonucleic acid (cDNA) synthesis and detection of TiLV by either conventional PCR or quantitative identification via qPCR using SYBR green I dye. Conventional PCR requires post-PCR steps and will simply inform about the presence of the virus. The latter approach will allow for absolute quantification of TiLV down to as little as 2 copies and thus is exceptionally useful for TiLV diagnosis in sub-clinical cases. A detailed description of the two PCR approaches, representative results from two laboratories and a thorough discussion of the critical parameters of both have been included to ensure that researchers and diagnosticians find their most suitable and applicable method of TiLV detection.

This protocol diagnoses Tilapia Lake Virus (TiLV) in tilapia tissues using RT-PCR methodologies. The entire method is described from tissue dissection to total RNA extraction, followed by cDNA synthesis and detection of TiLV by either conventional PCR or quantitative PCR using dsDNA binding a fluorescent binding dye.

The aim of this method is to facilitate the fast, sensitive and specific detection of Tilapia Lake Virus (TiLV) in tilapia tissues. This protocol can be ...

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles

Reptiles signal to conspecifics using lipids in their skin, primarily to enable mate tracking and assessment. The isolation of these lipids has utility in research focused on evolutionary patterns and mechanisms of chemical communication, in addition to understanding the waterproofing role of lipids in the evolution of terrestrial life. In an applied approach, such skin-based cues have potential use for wildlife managers dealing with invasive species. The main steps for quantifying reptile skin lipids in the protocol presented here include extraction, total lipid determination, and fractionation via column chromatography, the latter process resulting in purified eluates of compounds which can then either be analyzed to assign compound identifications (e.g., gas chromatography-mass spectrometry [GC-MS]) and/or used directly in more refined bioassays. Skin lipids can be extracted from living skin, shed skin, or dead whole animals, using nonpolar organic solvents (e.g., hexane, benzene, toluene). Extraction solubilizes the lipids and, then, the solvent can be evaporated to yield a measurable lipid-only extract. Fractionation involves the separation of the total lipid extract into specific eluates via traditional column chromatography. The total lipid extract is first bound to a substrate-based column (e.g., alumina) and, then, individual eluates (&#34;fractions&#34;) of solvent at specific volumes are passed sequentially through the column to elute sets of compounds from the lipid mixture based on common polarity. The fractions progress in polarity at a standardized sequence by increasing the relative amount of polar solvent (e.g., diethyl ether) in nonpolar solvent. In this manuscript, we describe several methods for extracting skin lipids of reptiles and, then, provide a standard protocol for isolating different sets of compounds based on polarity, using traditional column chromatography. Whole lipid extracts or specific fractions can, then, be used in bioassays to determine any biological activity elicited by the compounds therein.

In reptiles, skin lipids from conspecifics are crucial for sexual signaling, with potential use in invasive species management. Here, we describe protocols for extracting skin lipids from shed skin or whole animals, determining and analyzing the total lipid mass, and separating the lipids using fractionation via column chromatography.

Reptiles signal to conspecifics using lipids in their skin, primarily to enable mate tracking and assessment. The isolation of these lipids has utility in ...