Open Access Original article

Densitometry based microassay for the determination of lipase depolymerizing activity on polyhydroxyalkanoate

Diana Hooi-Ean Ch’ng and Kumar Sudesh*

Author Affiliations

Ecobiomaterial Research Laboratory, School of Biological Sciences, Universiti Sains Malaysia, Penang, 11800, Malaysia

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AMB Express 2013, 3:22  doi:10.1186/2191-0855-3-22

Published: 8 May 2013

Abstract

A novel method for the assay of polyhydroxyalkanoate (PHA)-degrading ability of triacylglycerol lipases was developed. By applying the natural affinity of lipases towards hydrophobic interfaces, a sensitive and rapid densitometry analysis for the evaluation of hydrolytic activity of lipase droplets towards PHA-coated surface was successfully carried out. We found that 12 out of 14 tested lipases which are of fungal, bacterial and animal origin were able to hydrolyze P(3HB-co-92 mol% 4HB) thin film. The patterns and opacity of the hydrolysis spots of lipases on PHA films allowed easy comparison of PHA-hydrolytic strength of lipases. Lipase from the bacterium Chromobacterium viscosum exhibited the highest PHA-degrading activity. The hydrolytic activity of lipases on water insoluble PHA, emulsified p-nitrophenyl laurate and olive oil were also compared and interestingly some lipases showed better activity when PHA was used as a substrate.

Keywords:
Polyhydroxyalkanoate; Lipase; Densitometry; 4-hydroxybutyrate; Hydrolysis