Bioremediation of Vegetable Oil Contaminated Soil with Two Microbial Isolates

Vegetable oil spills are becoming frequent and are potentially more challenging than petroleum hydrocarbon spills. Microbial lipases occupy a place of prominence among biocatalysts and are often used for the remediation of vegetable oil spills. There is a need for extensive characterisation of lipase for the treatment of vegetable oil-polluted sites. This work was carried out to monitor the degradation pattern of vegetable oil. Two microbial isolates previously isolated from an oil mill in Ibadan, Nigeria were used for the bioremediation experiment. Soil samples (with some purposely contaminated with 2 different vegetable oils) collected from the Nursery section of the Microbiology department as well as soil samples from the oil mill were all subjected to varied treatment processes. Field bioremediation using the isolates was carried out for 12 weeks. The isolates were identified, and microbial load and residual oil weight were determined during the degradation period using standard methods. The two isolates were identified as Pseudomonas fluoresecens and Candida parapsilosis. The result of sterile soil samples with and without mixing option, from palm oil and palm kernel purposely contaminated soils for all the various treatments, showed a general increase in total viable counts from the 2nd week to the 12th week, however in the non-sterile counterpart there was a steady increase from the 2nd week to the 8th week and subsequently, a gradual decrease from the 10th to the 12th week. The residual oil weight in the sterile purposely palm oil-contaminated soil, treated with the consortium (POC) non-mixed gave a reduction of value from 0.335 g on day 0 to 0.13025 g by the 12th week. From the oil mill non-sterile, treated with (POC) non-mixed sample, the residual weight after 12 weeks of treatment was 0.0043 g from an initial weight of 0.01 g. The microorganisms Pseudomonas fluoresecens and Candida parapsilosis had the potential for the degradation of fatty waste. They could therefore be employed in the environmental cleanup of the vegetable oil spill sites.

Microorganisms Associated with Vegetable Oil Polluted Soil

Vegetable oil Spills are becoming frequent and are potentially more challenging than petroleum hydrocarbon spills. Microbial lipases occupy a place of prominence among biocatalysts are often used for remediation of vegetable oil-polluted sites. This work was carried out to isolate microorganisms from oil-polluted sites and screen them for their lipolytic activity. Microorganisms were isolated from eight experimental soil samples contaminated with different types of vegetable oil, soil from an oil mill in Ibadan, and normal uncontaminated soil as a control. The isolates were characterized, identified and those common to at least one of the experimental sites and oil mill sites were screened for their lipolytic activity. Data obtained were analysed using Duncan Multiple Range Test. Seventy three microorganisms were isolated from the polluted soil and identified as species of Bacillus (16), Pseudomonas (12), Flavobacterium (6), Alcaligenes (2), Proteus (3), Micrococcus (1), Aspergillus (9), Penicillium (6), Saccharomyces (4), Geotrichum (1), Kluveromyces (1). Bacillus subtilis, Bacillus licheniformic, Pseudomonas cepacia, Pseudomonas fluorescens, Flavobacterium sp., Alcaligenes sp. and Candida parapsilosis which were common to at least one of the experimental site and oil mill site were preliminarily screened for lipolytic activity and all nine confirmed by presence of halos around the colonies. These screened organisms have potential for the degradation of fatty waste. They could therefore be employed in environmental clean-up of vegetable oil spill site.