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Vibrio is heterotrophic ubiquitous marine bacteria that plays dual role as putative halobiont and potential pathogen. Environment and diseases are inextricable hence the role of vibrio as a potential pathogen in the natural environment must be comprehended. Hence the present study aims at investigating the pathogenicity of Vibrio owensii on the post larvae of Litopenaeus vannamei. V. owensii isolated from the marine natural habitat of the Palk Bay province in India was highly resistant to ampicillin, methicillin, tetracycline and vancomycin. The strain also lacked pathogenicity against the post larvae of L. vannamei due to the absence of major virulence factors viz. Chitinase, phospholipase and hemolytic activity. Presumably this is the first report on the occurrence of V. owensii in the Indian waters therefore there arises a need to carry out more serious research on the pathogenicity of this species on other commercial crustaceans reared in the Indian aquaculture settings in order to apprehend its role as potential pathogen or the contrary.

Two halotolerant bacteria isolated from water samples of saltpan located at Ramanathapuram district, Tamil Nadu and tested their dye decolourization efficiency against four textile dyes. Of the tested strains, strain CMR2 showed maximum decolourization (98%) for Reactive Blue EFAF within 24 h. Further, strain CMR2 was identified as Exiguobacterium profundum using 16 s rDNA sequence analysis. It is noteworthy that the isolated halotolerant bacteria possess the ability to decolorize the reactive blue EFAF dye even in wide range of NaCl concentrations (5–30%) and pH (5–10). Decolourization efficiency was significantly increased upto 85% and 92% when the medium supplemented with starch and peptone as carbon and nitrogen source. Findings from UV–vis, FTIR spectral analysis before and after decolourization confirmed that the dye was decolourized completely via biodegradation. The present study suggest that Exiguobacterium profundum can be used as an effective candidate for the decolourization of waste water containing reactive blue EFAF.

In this study graphene/chitosan nanoparticles (GR/CS NCs) were developed. The homogenous combination of GR and CS was confirmed by FTIR spectroscopy. The combination of CS with GR sheets reduced the XRD intensity of the GR peak in GR/CS NCs, while TEM images revealed the immobile CS coating of GR sheets. Further, the anti-biofilm activity of GR/CS NCs was tested. The tests showed that the formation of biofilm by Pseudomonas aeruginosa and Klebsiella pneumoniae was inhibited at 40□g/mL GR/CS NCs up to 94 and 92 %, respectively. The intracellular and cell surface damage of the bacteria was observed by CLSM and SEM. Also, GR/CS NCs produced a toxic effect of 90 % on Artemia franciscana at 70□g/mL upon 24 h incubation. The recorded properties of the synthesized GR/CS NCs qualify them as potential agents against multi-drug resistant bacteria.