INFLUENCE OF POTASSIUM ALUM ON THE SYNTHESIS OF MICROBIAL SURFACE-ACTIVE COMPOUNDS

Abstract

Aim. The investigation of stimulating effect of potassium alum on biosurfactant synthesis by bacteria of different taxonomic groups. Methods. Bacterial strains were cultivated on nutrient media with the addition of alum. Biomass was determined by gravimetric method, total lipids were extracted with a mixture of chloroform: methanol (2:1), rhamnolipids concentration was determined by ortsyn method, peptydolipids – by forming a complex with methylene blue, exopolysaccharides – by gravimetric method; biocomplex PS (mixture of rhamnolipids and polysaccharides) was precipitated by acidification of the cell-free culture liquid to pH 3. Results. It was shown that potassium alum at concentrations of 0.5–2.0 g/l stimulate bacterial biomass accumulation and biosurfactant synthesis: rhamnolipids of the strain Pseudomonas sp. PS-17, peptidolipids of the strain B. subtilis F and trehalose lipids of the strain R. erythropolis Au-1 on 49–100%. Conclusion. It was shown the stimulating effect of potassium alum on biosurfactant synthesis by studied bacteria. Based on the experimental and literature data it was made the assumption that potassium alum initiates «quorum sensing» system. The application of potassium alum may make it possible to optimize the processes of biosurfactants isolation and reduce the cost of these products.