Various environmental factors including temperature, pH, and
salinity were optimized by conducting batch experiments in minimal
salt medium (MSM) containing 2% (v/v) crude oil. The composition
of medium was as per our previous study [18]. These flasks
were incubated in an orbital shaker at 35 C and 180 rpm for
1 week. Bacterial dry biomass was determined at regular intervals
by pelleting the bacterial cells through centrifugation [19]. These
experiments were conducted at pH 2.0–10.0, temperatures of
15–45 C, and sodium chloride (NaCl) concentrations of 2.0–8.0%
(w/v). Simultaneously, the biosurfactant production was studied
by an oil-displacement test under the optimal conditions [4]. Finally,
the diameter of the clear zone was then measured under visible
light.