Biosurfactant-producing bacteria were isolated from terrestrial samples collected in areas contaminated
with petroleum compounds. Isolates were screened for biosurfactant production using Cetyl Tri Ammonium
Bromide (CTAB)–Methylene blue agar selection medium and the qualitative drop-collapse test.
An efficient bacterial strain was selected based on rapid drop collapse activity and highest biosurfactant
production. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate,
2B, identified the bacterium as Pseudomonas sp. Five different low cost carbon substrates were evaluated
for their effect on biosurfactant production. The maximum biosurfactant synthesis (4.97 g/L)
occurred at 96 h when the cells were grown on modified PPGAS medium containing 1% (v/v) molasses
at 30 ◦C and 150 rpm. The cell free broth containing the biosurfactant could reduce the surface tension
to 30.14 mN/m. The surface active compound showed emulsifying activity against a variety of
hydrocarbons and achieved a maximum emulsion index of 84% for sunflower oil. Compositional analysis
of the biosurfactant reveals that the extracted biosurfactant was a glycolipid type, which was
composed of high percentages of lipid (∼65%, w/w) and carbohydrate (∼32%, w/w). Fourier transform
infrared (FT-IR) spectrum of extracted biosurfactant indicates the presence of carboxyl, hydroxyl and
methoxyl functional groups. The mass spectra (MS) shows that dirhamnolipid (l-rhamnopyranosyll-
rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C10-C10) was detected in abundance
with the predominant congener monorhamnolipid (l-rhamnopyranosyl--hydroxydecanoyl-
-hydroxydecanoate, Rha-C10-C10). The crude oil recovery studies using the biosurfactant produced
by Pseudomonas sp. 2B suggested its potential application in microbial enhanced oil recovery and
bioremediation.
Biosurfactant-producing bacteria were isolated from terrestrial samples collected in areas contaminatedwith petroleum compounds. Isolates were screened for biosurfactant production using Cetyl Tri AmmoniumBromide (CTAB)–Methylene blue agar selection medium and the qualitative drop-collapse test.An efficient bacterial strain was selected based on rapid drop collapse activity and highest biosurfactantproduction. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate,2B, identified the bacterium as Pseudomonas sp. Five different low cost carbon substrates were evaluatedfor their effect on biosurfactant production. The maximum biosurfactant synthesis (4.97 g/L)occurred at 96 h when the cells were grown on modified PPGAS medium containing 1% (v/v) molassesat 30 ◦C and 150 rpm. The cell free broth containing the biosurfactant could reduce the surface tensionto 30.14 mN/m. The surface active compound showed emulsifying activity against a variety ofhydrocarbons and achieved a maximum emulsion index of 84% for sunflower oil. Compositional analysisof the biosurfactant reveals that the extracted biosurfactant was a glycolipid type, which wascomposed of high percentages of lipid (∼65%, w/w) and carbohydrate (∼32%, w/w). Fourier transforminfrared (FT-IR) spectrum of extracted biosurfactant indicates the presence of carboxyl, hydroxyl andmethoxyl functional groups. The mass spectra (MS) shows that dirhamnolipid (l-rhamnopyranosyll-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C10-C10) was detected in abundance
with the predominant congener monorhamnolipid (l-rhamnopyranosyl--hydroxydecanoyl-
-hydroxydecanoate, Rha-C10-C10). The crude oil recovery studies using the biosurfactant produced
by Pseudomonas sp. 2B suggested its potential application in microbial enhanced oil recovery and
bioremediation.
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