Isolation and characterization of microalgae for biodiesel production from Nisargruna biogas plant effluent

• Five microalgae isolated and identified by 18S rRNA and 23S rRNA sequence analysis.
• The 23S rRNA gene from Monoraphidium sp. was first time sequenced in this study.
• Nutrient rich NBP effluent utilized for microalgal biomass and lipid production.
• Microalgal isolates were compared in Nisargruna biogas plant effluent and BBM.
• KMN3 showed high biomass (1.54 ± 0.04 g L−1) and lipid productivity (0.32 ± 0.06 g L−1).

Increasing energy demand and depleting fossil fuel sources have intensified the focus on biofuel production. Microalgae have emerged as a desirable source for biofuel production because of high biomass and lipid production from waste water source. In this study, five microalgae were isolated from effluents of Nisargruna biogas plants. These isolates were identified based on morphology and partial 18S and 23S rRNA gene sequences. Growth and lipid accumulation potential of these microalgae were investigated. One isolate, Chlorella sp. KMN3, accumulated high biomass (1.59 ± 0.05 g L−1) with moderate lipid content (20%), while another isolate Monoraphidium sp. KMN5 showed moderate biomass accumulation of 0.65 ± 0.05 g L−1 with a very high (35%) lipid content. The fatty acid methyl esters mainly composed of C-16:0, C-18:0, C-18:1 and C-18:2. This observation makes these microalgae immensely potential candidate for biodiesel production using the effluent of a biogas plant as feed stock.

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