Characterization and Lipolytic Activity of Bacteria Isolates from Freshwater Clam (Mercenaria Mercenaria) in Bayelsa State, Nigeria

Abstract

Lipases form an important group of relevant enzymes which have applications in various fields including; food, pharmaceutical, detergent, textile and cosmetic industries. Lipases can be produced from diverse sources including microorganisms. This study evaluated the potential of bacteria isolates from fresh-water clam Mercenaria Mercenaria to produce lipolytic enzymes. Ten samples of Clam (Mercenaria Mercenaria) were screened for the presence of lipase producing bacteria using classical culture methods. Eleven bacteria species were obtained, of which six (Actinomyces sp., E. coli, Bacillus sp., Pseudomonas sp., Clostridium sp. and Klebsiella sp.) produced lipases that had lipolytic activity in breaking down olive oil used in media supplementation. The best culture media and conditions for optimal production of lipases was studied and it was shown that supplementation of growth media with 2% dextrose at neutral pH gave the greatest yield of lipases when lipase producing isolates were grown in shake flasks. Measurement of biomass by culture and turbidimetric methods indicates that the highest cell mass was recorded by Pseudomonas sp at 7.8 x 105 CFU/ml, closely followed by Actinomyces sp. and Bacillus sp., at 6.2 x 105 CFU/ml and 5.3 x 105 respectively. The produced lipases were partially purified by precipitating with ammonium sulphate followed by dialysis. The total protein content of produced lipases was evaluated by the Lowry’s method, showing that estimated protein content followed the same trend as cell biomass with the highest recorded by Pseudomonas sp. at 1.53mg/ml, followed by Actinomyces sp. and Bacillus sp. at 1.47mg/ml and 1.32mg/ml respectively. The results obtained in this study shows that isolates obtained from freshwater clam can produce potent lipases which can be employed for industrial, food and other diverse uses