Abstract: One of the key factors in reducing the cost of the algal biomass production is the use of inexpensive sources of carbon, nitrogen and phosphorus. For this reason the use of wastewater for cultivation of microalgal biomass has the potential to address this problem. It is known that some of the microalgal strains can accumulate large amounts of lipids (on average 20 to 50% of the dry weight of cells). However, only a limited number of strains has the ability for growth in wastewater, maintaining high biomass productivity and optimal fatty acid composition of lipids. Therefore, the aim of this study is to screen for microalgae strains capable for growing in wastewater for identifying promising strains with a high content of lipids suitable for the production of high quality biofuel. In our work we studied new microalgae strains isolated from different geographical regions and climatic conditions of Russia. All strains were identified by sequencing of the 18S rRNA region. Selected isolates belong to the genera Chlorella, Botryococcus, Scenedesmus, Nannochloris, Neochloris, Bracteacoccus. The cultivation of microalgae was carried out in mixotrophic conditions on sterile synthetic wastewater media and unsterilized waster. The lipid content was determined by the Nile Red staining on microalgal cells in stationary growth phase and its composition was analyzed with GC/MS and TLC. The maximum specific growth rates were in the range of 0.25–0.30 day−1. Four microalgae strains Chlorella vulgaris IPPAS C-1, Chlorella sorokiniana IC-35, Chlorella vulgaris IC-76 and Chlorella sorokiniana IC-30 were selected as promising strains for the production of biodiesel according to the Nile red staining, biomass productivity and fatty acid composition. C16:0, C18:0, C18:1 and C18:2 fatty acids account for the main part of the lipids produced by these stains with the total content of saturated and monounsaturated fatty acids from 68.6% to 72.1%. The biomass productivity of these strains on sterile domestic wastewater were comparable to unsterilized wastewater medium. It is shown that the cultivation these strains in the unsterilized wastewater reduces the biomass yield by a factor of 1.5. This work was supported by the Russian Academy of Sciences and the Federal Agency for Scientific Organizations. Part of the work was supported by the Russian President's grant for leading scientific schools NSH-6902.2016.3.

Cite: Piligaev A.V. , Sorokina K.N. , Parmon V.N.
Isolation and Screening of High Lipid Strains of Microalgae for High Value Biofuel Production
In compilation Scientific papers 5th International conference "Sustainable Utilization of Tropical Plant Biomass: Bioproducts, Biocatalysts and Biorefinery (SutB4)" s. – Department of Agricultural Microbiology, Directorate of Natural Resource Management, Tamil Nadu Agri., 2016. – C.L-79.

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