Abstract

Oil and fat wastes produced by food industries are hydrophobic compounds that are difficult to remove from contaminated sites, that is why they are an important environmental issue. Biosurfactants can be used to enhance the accessibility of these compounds to microorganisms for degradation. The aim of this study was to determine favorable nutrient and culture conditions for biosurfactant production by Pseudomonas putida CB-100, using corn oil and glucose as a carbon source. The biomass production, surface tension and emulsification index (%E₂₄) were determined under all the established conditions using cells-free culture media. The biosurfactant produced in treatment 10 exhibited the highest decrease in surface tension (34.1 mN/m), while the one produced in treatment 9 presented the highest %E₂₄ (50%). The regression analysis showed that surface tension decrease was mainly affected by KH₂PO₄ (p<0.0001), K₂HPO₄ (p<0.0006), yeast extract (p<0.0006), and glucose (p<0.0008), whereas cell growth was affected by FeSO₄·7H₂O (p<0.0001), NH₄Cl (p<0.0001), glucose (p<0.0001) and temperature (p<0.0001). Surface tension decrease did not depend on cell growth (r=−0.43, p<0.02). The polar and non-polar components analyzed of biosurfactant produced in all the culture media were rhamnose and fatty acids, respectively. In conclusion, P. putida CB-100 produced biosurfactants with emulsifying capacity and surface tension reducing activity under suitable nutrient and culture conditions that could be used to remove oil from contaminated sites.

Key words: Cell growth, culture media, emulsifying capacity, fatty acids, nutrients, rhamnose, surface tension.