Production of Bioemulsifiers from Bacteria Grown on Hydrocarbons
Keywords:Biosurfactants, emulsifiers, soil flora, hydrocarbon contamination
This work aimed to identify biosurfactant-producing bacterial strains isolated from hydrocarbon-contaminated
sites and to evaluate their biosurfactant properties. The drop-collapse method and minimal agar added with
a layer of diesel as carbon source were used for screening, positive strains were able to grow in a liquid
medium, and surface tension and emulsification index were determined in cell-free supernatant and cell
suspension. 250 bacterial isolate were tested, and 16 were positive for the drop-collapse and hydrocarbonlayer agar method. Most of the strains were Pseudomonas, except for three strains (Acinetobacter, Bacillus,
and Rhodococcus). Surface tension was similar in cell-free and cell suspension measurements, with values
in the range of 58 to 26 (mN/m), and all formed stable emulsions with engine oil (77-92% E24). Considering
the variety of molecular structures among microbial biosurfactants, they have different chemical properties
that can be exploited commercially, for applications as diverse as bioremediation or degradable detergents.
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