Screening of Lipase-Producing Bacteria and Optimization of Lipase-Mediated Biodiesel Production from Jatropha curcas Seed Oil Using Whole Cell Approach

Biodiesel production from non-edible feedstocks, e.g., Jatropha curcas, by lipase-producing bacteria is considered a sustainable measure to reduce food versus fuel competition and dependency on fossil fuels. In this study, lipase-producing bacterial strains were isolated from soil contaminated with oil. Their biochemical and molecular identification was performed and their capacity to produce biodiesel from J. curcas seed oil was determined. Plackett-Burman and central composite designs were employed to optimize various factors for whole cell-based transesterification of J. curcas seed oil. Brevibacterium SB11 MH715025 and Pseudomonas SB15 MH715026 strains produced the highest volumetric yield of biodiesel (~ 97%). Pseudomonas SB15 MH715026 was identified as the most potent strain with the most optimum biodiesel yield on 37 °C, oil to methanol molar ratio of 1:9, and agitation at 100 rpm. Confirmation of fatty acid methyl esters was done through Fourier transform infrared spectroscopy. The infrared spectra were in the ranges 1735–1750 at cm−1 and 1300–1000 cm−1 that corresponds to C=O and C-O functional groups, respectively. The quality of biodiesel was evaluated and the fuel properties were determined for acid value, pour and cloud point, peroxide value, boiling point, and specific gravity. The values were 0.44 ± 0.1 mg potassium hydroxide (KOH)/g, 3 ± 0.1 °C, 4.1 ± 0.4 °C, 1.41 ± 0.1 milliequivalent (Meq) O2/kg, 260 ± 1 °C, and 0.87 ± 0.02 kg/m3, respectively. The fuel properties of biodiesel produced during this study were in accordance with quality standards specified by the American Society for Testing and Materials (ASTM D6751) and European Norms (EN-14103).