Characterization of bioemulsifying EPS from Halobacillus trueperi MXM-16, a halophilic adhered bacterial isolate from the mangrove ecosystem.

Exopolymeric substances (EPS) produced by bacterial cells play a crucial role in the interaction of the cells with the surrounding environment. Halobacillus trueperi manxer mangrove-16, an adhered bacterial isolate from the mangrove ecosystem was found to produce EPS that was observed by Alcian blue staining and congo red-coomassie blue agar. The EPS of the bacterial isolate exhibited emulsifying properties. Purification of the EPS by dialysis showed an emulsification index of 80% with hexadecane. Qualitative analysis and Fourier's Infrared spectroscopy (FTIR) revealed that the EPS was a glycoprotein in nature. The EPS showed no surface-active properties. Further exploration of the potential of the EPS interaction with metal solutions showed the ability of the bioemulsifier to cause precipitation in the metal solutions and particularly change the color of the Chromium (VI) solution. The scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) of the cells and EPS particularly indicated the interaction of the EPS with the (Fe0 ) zerovalent iron nanoparticles and its effect on the cells and EPS of the bacteria. It is therefore concluded that the EPS is a crucial component that anchors the bacteria to particulate matter in the mangrove ecosystem and also plays an important role in interaction with metals and hydrocarbons.

Studies on Siderophore and Pigment Produced by an Adhered Bacterial Strain Halobacillus trueperi MXM-16 from the Mangrove Ecosystem of Goa, India.

Mangroves are unique ecosystems in the coastal tropical and subtropical regions of the Earth. The fluctuation in salinity due to tidal action results in a prolific population of adhered halophilic and halotolerant bacteria in this ecosystem. In this study, a pigment producing adhered bacterial strain Halobacillus trueperi MXM-16 was isolated from mangrove plant litter of Goa. This strain was moderately halophilic, Gram positive rod, catalase positive and capable of utilizing sodium benzoate as a source of carbon. H. trueperi MXM-16, produced a siderophore that was hydroxamate in nature. The non-diffusible yellow pigment was a carotenoid and HPLC studies revealed a peak that was indicative of astaxanthin as one of the component. Further studies on the pigment exhibited its ability to chelate iron from the chrome azurol sulphonate medium behaving as an additional mechanism for iron acquisition.

Studies on the effects of zerovalent iron nanoparticles on bacteria from the mangrove ecosystem.

Zerovalent iron (ZVI) nanoparticles are gaining popularity in bioremediation of contaminated ground water and antimicrobial studies. In this study, ZVI nanoparticles were synthesized by borohydride method. The effect of these nanoparticles to alter the cell surface hydrophobicity of mangrove bacteria was studied by bacterial adhesion to hydrocarbon assay. The effect of these nanoparticles on the growth and extracellular polymeric substances (EPS) of a novel bacterial strain Halobacillus trueperi MXM-16 from mangroves was evaluated by growing the culture in the presence of ZVI nanoparticles and SEM. The change in the emulsifying ability of the cell-free supernatant of Halobacillus trueperi MXM-16 when grown in media amended with ZVI nanoparticles was also investigated by spectrophotometric analysis.