SCREENING OF THE ABILITY OF RHIZOSPHERE BACTERIA TO PRODUCE BIOSURFACTANTS

Abstract

Surfactants produced by microorganisms, known as biosurfactants, have recently found wide application in the industry, from cosmetology to oil processing. Biosurfactants are more tolerant to extreme environmental conditions and less hazardous for the environment as compared with their chemical analogues. Despite on the fact that many biosurfactant producers have been recently isolated and described, the challenge to explore new producers still remains very urgent. In the present study, the isolates obtained from rhizosphere soil were screened towards their abilities to emulsify oil and to decrease interface tension between oil and water. As a source of potential producers, rhizosphere soil of Latuca sativa was used. 12 rapidly growing isolates were cultivated in glycerol nitrate medium at 28? for 72 h. Emulsification activity (E24) and drop collapse tests were used to screen the abilities of the supernatants obtained. The lowest E24 was registered for 7 of 12 isolates (from 0% to 43%), while the highest one was registered for 5 from 12 isolates (50%). All these 5 isolates (12b, 19a, 20b, 23a and 26b) demonstrated high efficiency in drop collapse test as well (maximal scores in qualitative test). Besides, 3 other isolates were characterized as the most efficient in the drop collapse test (2c, 9a and 17a).