Oil pollution is common place in terrestrial and aquatic environments and causes significant ecological problems as seen from the Gulf of Mexico oil spill in 2010. Recent research has suggested that traditional treatment processes to decontaminate the polluted areas are limited in their application. Bioremediation in aquatic environments is limited by phosphorus and nitrogen availability as they are necessary for initial microbial cell growth. The use of nitrogen and phosphorus containing water soluble salts works effectively in laboratory conditions, but is readily washed away by surface agitation in aquatic environments.
Biosurfactants are surface active compounds produced by microorganisms, and these rapidly emulsify oil and therefore facilitate swift microbial growth.
This project aimed to evaluate the effect of biosurfactant, and fertilisers on biodegradation of crude oil by Bacillus megaterium, Corynebacterium kutscheri and Pseudomonas aeruginosa in shake flask and microcosm experiments.
Biosurfactants were produced by strains of the above bacteria, through fermentation, using peanut oil cake as the source of carbon.
Five different sets of shake flask experiments were carried out at 25oC, with crude oil that had a specific gravity of 0.844. Culture medium was inoculated with 1% inoculums containing 105 bacterial cells mL-1.
1) Bacterial cells + mineral salt medium + crude oil (normal)
2) Bacterial cells + mineral salt medium + crude oil + fertiliser
3) Bacterial cells + mineral salt medium + crude oil + biosurfactant
4) Bacterial cells + mineral salt medium + crude oil + fertiliser + biosurfactants
5) Mineral salt medium + crude oil (No bacterial cells= control)
The effect of fertiliser and biosurfactant concentration on biodegredadtion of crude oil was evaluated with various different concentrations.
It was evident in the results that all of the bacteria in the experiment utilise crude oil as their carbon source. Cell growth pattern for all three strains was in the following order 4), 3), 2) then 1), with maximum biodegradation occurring when both biosufactant and fertiliser were used.
The addition of biosurfactant along with fertiliser improved the oil degredation potential of all bacteria tested, interestingly biosurfactant addition alone also improved the degredation with very little difference between the two. Biosufactants alone are therefore capable of promoting biodegredation processes, but before such technology is applied to the field we need to study the possible adverse effects of biosurfactants produced by some microorganisms to other bacteria employed in bioremediation.
Thavasi, R., Singaram, J. & Banat, M. I., 2011. Effect of biosurfactant and fertilizer on biodegradation of crude oil by marine isolates of Bacillus megaterium, Corynebacterium kutscheri and Pseudomonas aeruginosa. Bioresource Technology. 102, 772-778.
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