Lipase activity of Pseudomonas sp. indigenous Bandar Lampung soil for biodiesel production and its response to alcohol.

Biodiesel production through enzymatic transesterification reactions using lipase catalysts has been widely developed. The transesterification reaction occurs in an organic environment because it uses a large amount of alcohol as an alkyl group donor. Therefore, the lipase used must have good stability in alcoholic solvents. In this study, the isolation and identification of alcohol-tolerant lipase-producing bacteria from soil samples in the fried rice seller's environment was carried out. The bacterial isolates obtained were identified and tested for their lipolytic activity in alcohol solvents (methanol and ethanol) using the plate assay method. Enzyme production is also carried out to obtain lipase enzymes which are then used as a catalyst for transesterification reactions between coconut oil and methanol with a ratio of 1:6 as much as 10% of the volume of oil. Pseudomonas sp. more stable in methanol than ethanol with optimum growth conditions at pH 7 media and incubation time of 36 hours with unit activity value of 23.06 U/mL. The purified lipase enzyme has a specific activity value of 22.48 U/mg and has optimum activity at a temperature of 35℃, pH 6, and 75% methanol concentration with a specific activity of 22.76 U/mg. The results of the analysis of the product of the transesterification reaction using GC-MS showed the presence of methyl ester compounds formed, namely methyl laurate 4.6%; methyl myristate 1.53%; and methyl palmitate 1.11%. The amount of methyl ester produced indicates that the transesterification reaction has not gone well because only a few fatty acids that make up the oil are converted to methyl esters. [ABSTRACT FROM AUTHOR]