Effect of different carbon sources on biosurfactant production by natural strains of Bacillus spp.

Biosurfactants are biotechnologically valuable metabolites of microorganisms. These compounds have not only surface-active properties, but also the ability to suppress growth of pathogenic and opportunistic bacteria and fungi. The wide range of characteristics and safety of biosurfactants have allowed them to find application in various industries. However, their production is currently problematic. The main problems in biosurfactants obtaining are associated with the search for highly active strains-producers, optimization of media composition for their cultivation, and production costs reduction. The aim of the work was to study the influence of different carbon sources on the biosurfactants production by natural bacilli strains. A screening of Bacillus spр. strains that possess surfactant activity from the Engineering Center “Prombiotech” collection was conducted. For the selected strains, the influence of sucrose, glycerol, mannitol and beet molasses on the biosurfactants production was shown. It was established that the Bacillus atrophaeus 7 strain is capable of producing surfaceactive compounds only when cultivated on media with molasses as the sole carbon source. On the contrary, for the Bacillus subtilis 1/8 strain, production of biosurfactants was recorded when using media with sucrose, glycerol, mannitol and beet molasses. The influence of cultivation duration on the surfactants accumulation in the medium for both bacilli strains was also established. The growth duration increase resulted in biosurfactants concentration decrease in the culture liquid.