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.

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Textile industries monopolize the use of synthetic and natural colors, claiming they are safe for the environment. These dyes have disastrous repercussions when released into the terrestrial and aquatic environment. The main purpose of the study was to isolate a biosurfactant‐producing bacterium from textile effluent‐contaminated soil and study its potential for dye degradation. Biosurfactant was extracted from Rhodococcus ruber strain TES III, a bacterium isolated from textile water contaminated soil. This biosurfactant‐producing bacterium was capable of decolorizing both synthetic dyes like methyl orange, methylene blue, and natural dyes like Indigo. There was a 2‐fold increase in methyl orange degradation after 48 hours, a 1‐fold increase in methylene blue degradation, and a 4.13‐fold increase in indigo dye degradation. Based on the foregoing data, we conclude that the biosurfactant‐producing bacteria Rhodococcus ruber strain TES III has a high potential for dye degradation and hence can be used in wastewater treatment of textile industries.

Calcium hydroxide nanoparticles (Ca(OH)2 NPs) are of great interest in the development of new products due to their antibacterial properties. Chemical precipitation process was used for synthesizing Ca(OH)2 NPs. The synthesized Ca(OH)2 NPs were characterized by using X‐ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transmission Infrared Spectroscopy (FTIR), UV‐Visible spectroscopy, DLS (Dynamic Light Scattering) techniques. Ca(OH)2 NPs were assessed for antibacterial activity against gram‐positive bacteria (Bacillus subtilis, Staphylococcus aureus) and gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa). The results showed reasonable bactericidal activity and flash out that the antibacterial activity of Ca(OH)2 had an important inhibitory activity against B. subtilis and P. aeruginosa which are gram‐positive and gram‐negative bacteria respectively. Reactive oxygen species (ROS) generation of Ca(OH)2 NPs were also studied and shows significant results against both gram negative and gram positive bacteria. From the analysis of the results, it was observed that Ca(OH)2 shows the best antibacterial activity against gram‐positive bacteria B. subtilis. Further, the possible mechanisms of antibacterial behaviour of Ca(OH)2 against each bacteria were suggested. These outcomes indicate that Ca(OH)2 could be utilized as a functional antibacterial material.

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