Abstract
Biosurfactants are amphiphilic compound, having hydrophilic and hydrophobic moieties enabling them to reduce surface and interfacial tension at the surface. Their unique properties are applied in various industries such as foaming and wetting agents, emulsifiers, detergents and bioremediation. A total of 98 isolates showed biosurfactant activity using hemolytic activity, drop collapse test and oil spreading assay. All isolates were rod-shaped, Gram positive and majority of them were non-endospore former. Only the isolates showing the highest percentage of emulsification index (E24) and ability to reduce tension were used for species identification using 16S rDNA gene sequencing which were isolates A1(6) and A2(1). Both isolates were identified as Bacillus sp. cp-h50 and Bacillus sp. XT-24 respectively, rod-shaped, endospore former and Gram positive. The biosurfactant produced by both species showed high emulsification index (E24) (A1(6), 63.3% and A2(1), 46.7%) and good surfactant capacity. The size of amplified gene of 16S rDNA gene was approximately 1.5 kb. These features provide evidence that both species could be a potential biosurfactant producer with proper optimization for the production of biosurfactant. The biosurfactant produced by both bacterial species were identified as surfactin using Fourier Transform Infrared Spectroscopy (FTIR).
Highlights
Bacteria can produce a wide range of extracellular products having many properties with many applications
One of them is biosurfactant in which the extracellular amphiphilic compounds produced by bacteria, fungi and yeast (Thavasi et al, 2011)[22]
Biosurfactants are naturally occurring surface-active compounds that are derived from microorganisms
Summary
Bacteria can produce a wide range of extracellular products having many properties with many applications. Biosurfactants are naturally occurring surface-active compounds that are derived from microorganisms. They are complex molecule that covers a wide range of chemical types which include glycolipid, fatty acids, peptides, antibiotics, lipopeptides and others. Biosurfactant producing microorganisms can be found naturally in the oil contaminated soil, rhizosphere soil and aquatic environment. Microorganisms exhibit the activity of emulsifying by producing biosurfactants They utilize the hydrocarbons as a substrate by mineralizing or converting them into harmless products. Many products are improperly accumulated in the environment causing contamination of soil and groundwater. This is due to the growth of industrial production (Rufino et al, 2012) [15]. The objectives of the study were to screen and isolate biosurfactant producing bacteria from soil in mangroves, dumping site and automobile workshop, to characterize and identify the type of biosurfactant produced and lastly to identify the best biosurfactant producing bacterial isolates using 16S rDNA gene sequencing
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