Characterization of biosurfactant production by indigenous bacteria from Sungai Dungun estuary, Terengganu by surface activity and emulsification test

Abstract

Natural surface-active agents or biosurfactants are derived particularly from bacteria and yeasts. These natural bio compounds have several advantages over synthetic surfactants such as more environmentally friendly, biodegradable, biocompatible, and low toxicity. Therefore, many efforts have focused on investigating biosurfactants including the isolation of new potent biosurfactant producers. In the present study, twelve potent biosurfactant producing bacteria were successfully isolated from oil-contaminated water and sediment samples from Sungai Dungun estuary by using Minimal Salt Media (MSM) with the addition of 1 % (v/v) engine oil. From characterization tests, one isolate named as DSB7 demonstrated the highest activity among others by semi-quantitative tests i.e., oil spreading technique and drop collapse test. Besides, it has the lowest value of 38.48 mN/m in water surface tension measurement and emulsification index of 53.57 % and 30.0 % for kerosene and used engine oil respectively. As for the molecular identification of the isolate, it showed the highest similarity to Pseudomonas aeruginosa based on 16S rRNA sequence analysis.