Characterisation of Some Selected Bacterial Isolates from Vegetable Oil Contaminated Soil

Abstract

Microbial lipases occupy a place of prominence among biocatalysts and are often used for various biotechnological applications. Because of huge variation in applications, the availability of lipases with specific characteristics is still a limiting factor. There is therefore need for extensive characterisation of lipase for various applications. This work was carried out to characterise lipases from some selected bacterial isolates. Isolates identified as Bacillus subtilis, Bacillus licheniformis, Pseudomonas cepacia Pseudomonas fluorescens, Alcaligenes sp. and Flavobacterium sp. from a vegetable oil contaminated soil were characterized. Temperature, pH and ion concentration, (NaNO3 and MgSO4), incubation time, agitation speed, carbon sources and nitrogen sources were optimised for growth and lipase activity. Increase in microbial growth does not necessarily suggest increase in lipolytic activity as generally observed from this study.  Temperature, pH, incubation time and agitation speed which had optimum enzyme activities for crude enzyme of Pseudomonas fluorescens (0.8 U/mL), were 27 oC, 7.0, 24 h, and 0 rpm respectively. Growth was not generally supported by AgN03 in all the organisms selected but supported by KNO3. However MgSO4 generally supported lipase production. Olive oil and peptone as sources of carbon and nitrogen respectively supported both growth and lipase production in the selected organisms. These bacterial isolates characterized had lipolytic activities, hence they have high potential for various biotechnological applications.