Abstract

SASTOQUE-CALA, Leonardo; COTES-PRADO, Alba M.; RODRIGUEZ-VA ZQUEZ, Refugio  and  PEDROZA-RODRIGUEZ, Aura M.. Effect of nutrients and fermentation conditions on the production of biosurfactants using rhizobacteria isolated from fique plants. Univ. Sci. [online]. 2010, vol.15, n.3, pp.251-264. ISSN 0122-7483.

Objective. To isolate biosurfactant-producing microorganisms from the rhizosphere of fique and to select the best genus to evaluate the effect of nutritional and fermentation conditions on the production of rhamnolipids. Materials and methods. Rhizospheric soil was sampled in three areas of Cauca. The best genus was selected for the experimental designs (Plackett Burman and 2² factorial) and to find the production conditions for the growth kinetics at an Erlenmeyer flask scale. Results. Isolates from the rhizosphere of fique plants were from groups (or genera) of Bacillus, Pseudomonas and Actinomycetes, being Pseudomonas the more responsive in preliminary testing for emulsification. From the results of the experimental designs and the kinetics of production, we found that rhamnose synthesis associated with rhamnolipids (3.2 g/l) and emulsification (68% EC24) was significantly favored (p <0.0001) by cultivating an inoculum of 10% v/v of Pseudomonas fluorescens in a medium composed of: soybean oil 2% (v/v), K₂HPO₄ 0.2% (w/v), yeast extract 0.4 g/l, NH₄NO₃ 3.7 g/l, 1 ml trace elements (CoCl₃ 20 mg/l, H₃BO₃30 mg/l, ZnSO₄10 mg/l, Cu₂SO₄1 mg/l, Na₂MoO₄3 mg/l, FeSO ₄10 mg/l MnSO₄2,6 mg/l) and pH 7.2. Conclusion. Of all the microbial genera isolated from the rhizosphere of fique, Pseudomonas fluorescens had the greatest potential in the production of biosurfactants of the rhamnolipids family.

Keywords : Pseudomonas fluorescens; biosurfactant; rhamnose; emulsification index; soybean oil.

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