A novel alkaline lipase from Ralstonia with potential application in biodiesel production

With the aim of isolating a biocatalyst able to catalyze biodiesel production from microbial source, Ralstonia sp. CS274 was isolated and a lipase from the strain (RL74) was purified. Molecular weight of RL74 was estimated to be 28,000 Da by SDS–PAGE. The activity was highest at 50–55 °C and pH 8.0–9.5 and was stable at pH 7.0–12.0 and up to 45 °C. It was resistant to oxidizing and reducing agents and the activity was enhanced by detergents. RL74 was 1,3 specific and Km and Vmax for p-nitrophenyl palmitate were 2.73 ± 0.6 mM and 101.4 ± 1.9 mM/min mg, respectively. N-terminal amino acid sequence showed partial homology with that of Penicillium lipases. RL74 produced biodiesel more efficiently in palm oil than in soybean oil; and the production was highest at pH 8.0, at 5% methanol and at 20% water content.