Characterization of a novel alkaline-stable lipase from Acinetobacter haemolyticus KV1 isolated from an oil palm mill effluent

Abstract

Aims: Bioprospecting for lipases remains limited despite its great deal of industrial application. This study reports on the purification and characterization of a novel lipase KV1 from Acinetobacter haemolyticus strain KV1. Methodology and results: Strain KV1 was identified as A. haemolyticus using the 16S rDNA sequencing, phylogenetic and BIOLOG assessments. The intracellular lipase was purified to homogeneity using consecutive treatments of ammonium sulfate precipitation, dialysis and DEAE-cellulose ion exchange chromatography, affording ~3.5-fold of the purified lipase with an estimated relative molecular mass of 37 kDa. The PCR product of lipase KV1 revealed that the retrieved sequence contained the proposed complete lipase gene sequence at nucleic acid positions 1-954. The purified lipase exhibited its maximum relative activity at 40 °C and pH 8.0, respectively. Interestingly, the novel alkalophilic lipase KV1 retained its relative activities (> 50%) even up to 24 h between pH 7-11. Conclusion, significance and impact of study: The findings revealed that relative activities of the intracellular lipase KV1 were the highest at 40 °C and pH 8.0, respectively. Pertinently, the remarkable stability of the lipase KV1 over a broad range of pH values (pH 7-11), as well as an optimum activity at 40 °C indicated it was an excellent enzyme for producing a wide range of industrial detergents, cleaning up enviro-agro-industrial wastes as well as catalysts in synthetic manufacturing processes. Therefore, its full characterization reported here deserves scientific and economic considerations.