Carbon dioxide biofixation by free air CO2 enriched (FACE) bacterium for biodiesel production

Abstract

Abstract Microbial CO2 fixation is an emerging strategy to mitigate CO2 emissions and its transformation into value added products by exploring potential bacteria. In this study, bacterial strains were isolated from Free Air CO2 Enrichment (FACE) soil area and screened for carbon dioxide sequestration and lipid production. CO2 sequestration efficiency of bacterial strains was determined via enzymatic activity of carbonic anhydrase (CA) and ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisCO) involved in carbon concentrating mechanism (CCM). Bacillus sp. SS105 was found to be the most efficient strain for CCM and showed maximum biomass productivity (381 mg l−1d−1), and CO2 consumption rate (287.21 mg l−1d−1). Western blot analysis confirmed the presence of RuBisCO large subunit in Bacillus sp. SS105. Further genes were amplified from SS105 genome using degenerate primers. Amplified gene sequences showed homology with CA and rbcL gene. Bacterium SS105 has shown higher lipid production as compared to other strains. The lipid yield increased 1.5-fold after optimization. The chemical structure and composition of Fatty acid methyl esters (FAMEs) were characterized by GC ­ MS, FTIR and 1H NMR. Total FAMEs content was quantified as 120 mg l−1 and showed 51 % of saturated and 49% of unsaturated fatty acids. Among the FAMEs, palmitic (37.80 %) and oleic acid (37.88 %) were present in high proportion which is a prerequisite for good quality biodiesel. The study highlights the importance of Bacillus sp. SS105 in CO2sequestration and biodiesel production with potential future applications.