Deciphering the molecular diversity of related halophilic Bacillus sp. isolated from Sambhar Lake and the functional characterizations of surfactin

Abstract

The Sambhar Salt Lake in Rajasthan, India, offers a unique opportunity to explore halophilic surfactin-producing microorganisms with industrial application. The phylogenetic study, comparative genomics combined with chemotaxonomic research provided insight into the interspecies relativeness of Bacillus sp. Considering the nonribosomal protein sequences (NRPS), Bacillus haynesii strain SAII strain and Bacillus swezeyi strain SEIII showed a high degree of conservation. In silico studies of the isolated Bacillus sp. confirmed the presence of NRPS indicating the presence of surfactin-type lipopeptide biosurfactants. Structural investigation using Fourier transform infrared spectroscopy, liquid quadrupole triple quadrupole mass spectrometry, 1 H Nuclear mass resonance of the crude biosurfactant revealed further similarities among these two Bacillus species. Methyl esters of the crude biosurfactant indicated high likeliness among them and indicated the presence of pentadecanoic acid and tetradecanoic acid as the crucial fatty acids. Enhanced recovery of oil from contaminated sand using 100% crude biosurfactant ranged from 20% AE 0.05 to 69.20% AE 1.22. This opens the door to a bright future for understanding the molecular diversity of closely related halophilic Bacillus sp. and the potential use of the extracted biosurfactants for bioremediation of contaminants.

Removal of Heavy Metal by Biosurfactant Producing Novel Halophilic Staphylococcus sciuri subsp. rodentium Strain SE I Isolated from Sambhar Salt Lake

“…Comparable investigations on biosurfactant characterization have found similar mass patterns for lipopeptides predominantly belonging to the surfactin family peaks in Bacillus amyloliquefaciens MT45 [55] . This could be because of the breakdown of the product at the junction of leucine and fatty acids, as well as glutamic acid and leucine [34] . Even after the product breakdown, charges were detected on the hexapeptide residue composed of leucine‐leucine‐valine‐aspartic acid‐leucine‐leucine.…”

“…Based on their gram staining characteristic, cell shape, and colony morphology, enriched cultures were selected and purified by repeated streaking. The biochemical characteristics of the isolated bacterial strain were systematically performed according to Bergey's manual of determinative bacteriology [34,78] . The isolated pure colonies were stored at 4 °C until further use.…”

“…The gas chromatography-mass spectrometric (GC-MS) analysis was carried out to detect the fatty acid composition from extracted biosurfactants as described earlier by Sharma. [34] To this crude biosurfactant extract (2 mg) was esterified using 2 % methanolic sodium hydroxide solution. After acidic hydrolysis, 30 ml methanol was added and refluxed at 100 0 C for 30 min.…”

“…This bacterial strain showed better emulsification and ability to reduce surface tension in comparison to the Bacillus strains isolated from Sambhar Lake. [34] The authors reported the highest reduction in surface tension in strains SAII and SE III respectively as 45.44 � 0.61 mN/m and 44.24 � 0.71 mN/m after 24 h whereas SE I strain showed a reduction in surface tension to 46.23 � 0.46 mN/m after 24 h. Correspondingly, the maximum emulsification index of SAII and SE III was 40 % and 37.03 % after 24 h. However, strain SE I maintained the highest 40 % emulsification index even after 96 h. Arima and coworkers [35] reported that purified surfactin reduced the surface tension of water to 27.90 mN/m at a concentration of 0.005 %. [35]…”

Dye Decolorization by Rhodococcus ruber Strain TES III Isolated from Textile Effluent Wastewater Contaminated Soil

“…This was done to understand the change in the nature of the functional group on the extensive growth of the bacterial culture in dye-containing solution. [39]…”