Aquat. Living Resour.
Volume 28, Number 2-4, April-December 2015
|Page(s)||99 - 109|
|Published online||30 March 2016|
Influence of low salinity stress on virulence and biofilm formation potential in Vibrio alginolyticus, isolated from the Gulf of Khambhat, Gujarat India
1 Marine Biotechnology and Ecology
Division, CSIR Central Salt and Marine Chemicals Research Institute,
2 Academy of Scientific and Innovative Research (AcSIR), CSIR-CSMCRI, G.B. Marg, 364002, Bhavnagar, India
b Corresponding author:
Accepted: 15 January 2016
The Gujarat government has proposed a project to convert a part of the Gulf of Khambhat (GoK), located in western India, into the world’s largest man-made freshwater reservoir in the near future (http://www.kalpasar.gujarat.gov.in/mainpage.htm). Anticipating the impact of the change on native bacterial communities, 145 bacteria were isolated initially from different parts of GoK, and further narrowed down to 12 on the basis of diversified geographic distribution in the GoK for further study. All the isolates were able to grow in the complete range of salinity tested (1% to 4%), however an influence of salinity on biofilm formation was observed in only a few isolates. Interestingly, two isolates (91 and 103) identified as Photobacterium damselae and Vibrio alginolyticus by MIDI and 16sr RNA sequencing were able to produce biofilm only at low salinity conditions (1% to 2%). Along with biofilm formation, isolate 103 showed higher virulence potential in an Artemia model only at lower salinity (1%). Therefore, isolate 103 was selected for further characterisation and the image of biofilm developed on a time-scale basis (up to 24 h) for this isolate was studied using a scanning electron microscope (SEM). The change in biofilm surface morphology was studied by atomic-force microscopy (AFM). Live/dead bacterial composition of 24 hour-old matured biofilm also showed that the number of dead bacteria was higher than live bacteria. To the authors’ best knowledge, this is the first study showing a change in virulence potential as well as biofilm formation by marine bacteria, exclusively under low salinity stress.
Key words: Biofilm / Salinity stress / GoK / Marine Vibrio
© EDP Sciences 2016
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