Surfactant-forming activity of bacteria Rhodococcus sp. G13

Abstract

In this research we investigated surfactant-forming and emulsifying activity of the oil-destroying bacterial strain Rhodococcus sp. G13 when cultivated on mineral medium containing various sources of nitrogen (NaNO3, KNO3, (NH4)2SO4, NH4NO3) and phosphorus (KH2PO4, K2HPO4, Na2HPO4) in the presence of several carbon sources (glucose, ethanol, hexadecane). The emulsification index of hexadecane by Rhodococcus sp. G13 cells ranged from 23.8±1.5% to 54.1±1.2% depending on the salt composition of the mineral medium and the type of organic compounds as the carbon source are used. At the same time, when cell-free supernatant was used in the experiment, this index was about 2.76±0.16%. The ability of the bacterial cells to reduce the surface tension of the liquid was also evaluated, which was from 13.95±0.8% to 56.04±1.1% compared to the control medium. The colorimetric method [4] demonstrated that the level of biosurfactant synthesis by Rhodococcus sp. G13 reached up to 13.54±1.4 mg/L.