Characterization of endolithic cyanobacterial strain, Leptolyngbya sp. ISTCY101, for prospective recycling of CO₂ and biodiesel production.

The present investigation evaluates the potential of an endolithic cyanobacterium isolated from marble rock to utilize sodium bicarbonate (NaHCO₃) as carbon source for prospective recycling of CO₂ into biodiesel. Microalgae thriving on marble were cultured and subjected to increasing NaHCO₃ concentration. The most competent isolate was identified and characterized in terms of growth, lipid content and fatty acid profile. A semicontinuous mesh incubator was designed for biofilm development. Isolate ISTCY101 was identified as Leptolyngbya sp. by 16S rRNA sequencing. Leptolyngbya ISTCY101 efficiently used BG-11 (50 mM NaHCO₃) and artificial seawater medium (25 gL(-1) NaCl) with biomass productivity 78.9 and 75.74 mg L(-1)d(-1), respectively. Maximum areal biomass productivity of 2.01 gm(-2)d(-1) was recorded in the mesh incubator, with complete exclusion of centrifugation for harvesting. Lipid content varied from 16% to 21%, consisting predominantly of C16:0, C16:1, C18:0, C18:1 fatty acids (>60%) making promising feedstock for biodiesel production.