Lipolytic Activity and Molecular Identification of Pseudomonas aeruginosa and Lysinibacillus sphaericus Isolated from Domestic Oil Rich Wastewater

Abstract

Microbial lipases have been heightened in bioremediation and various industries. Place and Duration of Study: Department of Microbiology, Ekiti State University, Ado-Ekiti, Ekiti State, Nigeria, between September 2010 and August 2011. To identify the lipolytic enzyme producing microbial strains in domestic oil rich wastewater, the 16S rRNA gene was amplified and sequenced. The sequences were used to identify the strains by comparing with related sequences in database using BLAST analysis. The enzyme activity was quantified by HPLC analysis. All the lipolytic bacteria showed appreciable growth rates in the wastewater (between 0.67 and 1.67 mg/day) within 5 days. The most effective lipolytic bacteria isolates in the oil-rich wastewater were two species of the genus Pseudomonas and one of Bacillus. Comparing the weights on the first day to the twelfth day values when lipolytic organisms were grown in palm oil, some appreciable increases in weight difference were recorded in some isolates: 28.3%, 7.84%, 4.44% and 6.98% for Pseudomonas, Staphylococcus, Bacillus and Klebsiella, respectively. The weight increase of each of the microbial cells in palm oil culture was usually lesser than what was obtained in the oil-rich wastewater culture. Two isolates showed high similar sequence (99%) to that of Pseudomonas aeruginosa and Lysinibacillus sphaericus, respectively. From palm oil, Lysinibacillus sp. produced various forms of fatty acids in the medium, including myristic acid (2.61%), palmitic acid (6.22%), stearic acid (5.18%) and arachidic (3.66%). These strains are versatile in utilizing the limited nutrient and had the ability to grow appreciably in the toxic condition (soap solution), suggesting that they may serve as candidates in treating dietary oil-rich wastewater.