Bacterial Lysis of Microalgal Cells

Meng Wang, Wenqiao Yuan^*

Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, USA.

DOI: 10.4236/jsbs.2014.44022                

Abstract

This short communication reports a pioneering research of using bacteria for simultaneous algal cell disruption and cell wall/membrane utilization. Microalgae are regarded as one of the most promising feedstock that can potentially address the twin challenges of energy security and environmental protection due to their fast growth rate, high lipid content and CO2 biofixation capabilities. However, different from their terrestrial oil crops, the extracellular coverings of algae vary significantly, ranging from multiple layers of elaborate scales to highly mineralized coats to complex cell walls consisting of structural fibrils enmeshed in complex matrices. These strong cellular walls and membranes are resistant to disintegration, which makes lipid extraction from microalgae difficult. A bacteria-assisted algal cell disruption and lipid extraction method was studied here. The bacteria Sagittula stellata showed strong algicidal activity against two microalgae, Nannochloropsis oculata and Dunaliella salina. The algicidal rate reached 64.7% on N. oculata and 52.4% on D. salina in six days. A decrease in chlorophyll-a fluorescence density of both algae and bacteria addition was also observed. After 6-day treatment by S. stellata, hexane-extracted crude lipid contents increased from 32.9% to 45.7% and from 19.6% to 36.4% for N. oculata and D. salina, respectively, when compared with no bacterial addition. The preliminary results concluded that S. stellata was effective in the lysis of microalgal cells for effective lipid recovery.

Keywords

Microalgae, Cell Lysis, Lipid Extraction

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Manage, P.M., Kawabata, Z. and Nakano, S. (2000) Algicidal Effect of the Bacterium Alcaligenes denitrificanson on Microcystis spp. Aquatic Microbial Ecology, 22, 111-117. http://dx.doi.org/10.3354/ame022111
[2]	Mayali, X. and Azam, F. (2004) Algicidal Bacteria in the Sea and Their Impact on Algal Blooms. Journal of Eukaryotic Microbiology, 51, 139-144. http://dx.doi.org/10.1111/j.1550-7408.2004.tb00538.x
[3]	Roth, P.B., Twiner, M.J., Mikulski, C.M., Barnhorst, A.B. and Doucette, G.J. (2008) Comparative Analysis of Two Algicidal Bacteria Active against the Red Tide Dinoflagellate Karenia brevis. Harmful Algae, 7, 682-691. http://dx.doi.org/10.1016/j.hal.2008.02.002
[4]	Bai, S.J., Huang, L.P., Su, J.Q., Tian, Y. and Zheng, T.L. (2011) Algicidal Effects of a Novel Marine Actinomycete on the Toxic Dinoflagellate Alexandrium tamarense. Current Microbiology, 62, 1774-1781. http://dx.doi.org/10.1007/s00284-011-9927-z
[5]	Adam, F., Abert-Vian, M., Peltier, G. and Chemat, F. (2012) “Solvent-Free” Ultrasound Assisted Extraction of Lipids from Fresh Microalgae Cells: A Green, Clean and Scalable Process. Bioresource Technology, 114, 457-465. http://dx.doi.org/10.1016/j.biortech.2012.02.096
[6]	Lam, M.K. and Lee, K.T. (2012) Microalgae Biofuels: A Critical Review of Issues, Problems and the Way Forward. Biotechnology Advances, 30, 673-690. http://dx.doi.org/10.1016/j.biotechadv.2011.11.008
[7]	Araujo, G.S., Matos, L.J.B.L., Fernandes, J.O., Cartaxo, S.J.M., Gonçalves, L.R.B., Fernandes, F.A.N. and Farias, W.R.L. (2013) Extraction of Lipids from Microalgae by Ultrasound Application: Prospection of the Optimal Extraction Method. Ultrasonics Sonochemistry, 20, 95-98. http://dx.doi.org/10.1016/j.ultsonch.2012.07.027
[8]	Boden, R., Murrel, J.C. and Schäfer, H. (2011) Dimethylsulfide Is an Energy Source for the heterotrophic Marine Bacterium Sagittula stellata. FEMS Microbiology Letters, 322, 188-193. http://dx.doi.org/10.1111/j.1574-6968.2011.02349.x
[9]	Ding, Y.X., Chin, W.C., Rodriguez, A., Hung, C.C., Santschi, P.H. and Verdugo, P. (2008) Amphiphilic Exopolymers from Sagittula stellata Induce DOM Self-Assembly and Formation of Marine Microgels. Marine Chemistry, 112, 11- 19. http://dx.doi.org/10.1016/j.marchem.2008.05.003
[10]	González, J.M., Mayer, F., Moran, M.A., Hodson, R.E. and Whitman, W.B. (1997) Sagittula stellata gen. nov., sp. nov., a Lignin-Transforming Bacterium from a Coastal Environment. International Journal of Systematic and Evolutionary Microbiology, 47, 773-780. http://dx.doi.org/10.1099/00207713-47-3-773
[11]	Shen, Y., Pei, Z.J., Yuan, W.Q. and Mao, E.R. (2009) Effect of Nitrogen and Extraction Method on Algae Lipid Yield. International Journal of Agricultural and Biological Engineering, 2, 51-57.
[12]	Azachi, M., Sadka, A., Fisher, M., Goldshlag, P., Gokhman, I. and Zamir, A. (2002) Salt Induction of Fatty Acid Elongase and Membrane Lipid Modifications in the Extreme Halotolerant Alga Dunaliella salina. Plant Physiology, 129, 1320-1329. http://dx.doi.org/10.1104/pp.001909
[13]	Converti, A., Casazza, A.A., Ortiz, E.Y., Perego, P. and Borghi, M.D. (2009) Effect of Temperature and Nitrogen Concentration on the Growth and Lipid Content of Nannochloropsis oculata and Chlorella vulgaris for Biodiesel Production. Chemical Engineering and Processing, 48, 1146-1151. http://dx.doi.org/10.1016/j.cep.2009.03.006
[14]	Leach, G., Oliveira, G. and Morais, R. (1998) Spray-Drying of Dunaliella salina to Produce a β-Carotene Rich Powder. Journal of Industrial Microbiology and Biotechnology, 20, 82-85. http://dx.doi.org/10.1038/sj.jim.2900485
[15]	Imai, I. (1997) Algicidal Ranges in Killer Bacteria of Direct Attack Type for Marine Phytoplankton. Bulletin of the Plankton Society of Japan, 44, 3-9.
[16]	Wang, M., Yuan, W., Jiang, X., Jing, Y. and Wang, Z. (2014) Disruption of Microalgal Cells Using High-Frequency Focused Ultrasound. Bioresource Technology, 153, 315-321. http://dx.doi.org/10.1016/j.biortech.2013.11.054
[17]	Chiu, S.Y., Kao, C.Y., Tsai, M.T., Onga, S.C., Chenb, C.H. and Lin, C.S. (2009) Lipid Accumulation and CO2 Utilization of Nannochloropsis oculata in Response to CO2 Aeration. Bioresource Technology, 100, 833-838. http://dx.doi.org/10.1016/j.biortech.2008.06.061
[18]	Weldy, C.S. and Huesemann, M. (2007) Lipid Production by Dunaliella salina in Batch Culture: Effects of Nitrogen Limitation and Light Intensity. US DOE Journal of Undergraduate Research, 7, 115-122.