Biodegradation of Palm Oil Mill Effluent (POME) and Lipase Activity by Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans

Abstract

Aims: To evaluate the biodegradation of palm oil mill effluent and lipase activity by Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans treatment. Place and Duration of Study: Department of Microbiology, University of Abuja, Abuja and  Microbiology laboratory of the National Institute of Pharmaceutical Research Development (NIPRD), Idu, FCT-Abuja, Nigeria, between July 2014 and September 2014. Methodology: Some physicochemical properties of the POME were analysed. Samples of POME were inoculated with Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. Microbial growth was measured by determining the total viable counts in a medium containing POME. The isolates were screened for lipase activity and degradation products were determined by gas chromatography-mass spectrometry (GC-MS) analysis. Results: The highest lipase activity was recorded on the 8th day by C. albicans as (29.83±1.40 U/ml) followed by P. aeruginosa (29.02±1.02 U/ml) while the least lipase activity was produced by B. subtilis (19.08±0.40 U/ml). The total viable counts of the microbial isolates during biodegradation of POME revealed that the highest colony counts of P. aeruginosa (8.30×109 cfu/ml ) and B. subtilis (7.30×109 cfu/ml) occurred on the 12th day while the highest colony count of C. albicans was observed on the 16th day (6.35×109 cfu/ml). The degradative enzyme (lipase) produced by the microbial isolates was capable of breaking down complex substrates in nature, and thus may be responsible for the biodegradation of POME polluted habitats. However, the GC-MS showed that oleic acid (omega-9 fatty acid), hexadecanoic acid (palmitic acid) and octadecanoic acid (stearic acid) which were the main compounds present in the POME were not degraded by the three organisms at the end of the growth period. Conclusion: The present study revealed that P. aeruginosa, B. subtilis and C. albicans are good degraders of palm oil mill effluent and the enzyme (lipase) produced was capable of catalysing the breakdown of complex substrates in POME.