Abstract
Biosurfactant producing bacteria (28 isolates) were isolated from 30 oil contaminated soils and tested for production of biosurfactant by different screening methods. About 75% of the isolated bacteria showed no blood hemolysis and their emulsification index for hexane and xylene ranges from 28-35% and 30-45% respectively. Biosurfactant producing ability was confirmed by other tests where about 40% of isolates showed positive oil spreading activity, hydrocarbon overlay and 67% showed to be positive for drop collapsing test. 16s RNA sequencing of the most active isolates revealed one Stenotrophomonas maltophila, two Bacillus spp. and two Achromobacter spp. Biosurfactants extracted from these isolates showed variable antimicrobial activity against Staphylococcus aureus, E. coli and Pseudomonas aeruginosa. This study demonstrated that the biosurfactants produced by these bacteria could be used in combination with antibiotics for treating bacterial infections. Further study is required for enhancing biosurfactant production by bacterial isolates to be used environmentally for bioremediation of oil contaminated soils.
Highlights
: Surface active agents are amphiphilic molecules having the ability to reduce the surface and interfacial tension (Sridhar et al, 2015) Surfactants represent an important class of chemical products owing to their surface active properties showing industrial, agricultural and environmental applications (Nitschke & Costa, 2007)
Pure colonies isolated on MSM agar plates were further screened for biosurfactant producing activity by hemolytic activity, oil spreading test, emulsification index test hydrocarbon overlay agar methods
As previously reported by (Satpute et al, 2010), several screening methods could be included in the primary screening of potential biosurfactant production
Summary
: Surface active agents (surfactants) are amphiphilic molecules having the ability to reduce the surface and interfacial tension (Sridhar et al, 2015) Surfactants represent an important class of chemical products owing to their surface active properties showing industrial, agricultural and environmental applications (Nitschke & Costa, 2007). A great attention was given to biologically produced surfactants (biosurfactants or bioemulsifiers) which are diverse group of compounds produced by microorganisms( Sridhar et al .,2015). Contamination of terrestrial and aquatic ecosystems with oil results in emergence of microbial community capable of biosurfactant production and it greatly opens promosing ways for isolation of novel bioemulsifier producing strains(Chikere et al, 2009; Panjiar et al, 2015) Acinetobacter, Pseudomonas, Bacillus, Rhodococcus, Acinetobcter and Enterobacter have been reported to be biosurfactent producers(Panjiar et al, 2015). The incredible interest given to the naturally produced amphiphilic biosurfactants (BS) and bioemulsifiers (BE) compounds is due to potential use instead of synthetic surfactants and so they may be applied in industry and environment (Satpute et al, 2010). The objective of this study was to isolate bacteria from oil contaminated soils and screening of their biosurfactant producing ability. As well as studying the biosurfactant which are extracted from different isolates screening of its antimicrobial activity against some bacteria was carried out
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