Research Projects

Mangroves found in most tropical and subtropical marine regions in the intertidal zones of river deltas hold a greater diversity of flora, fauna, and microorganisms. Being associated with the marine ecosystem, they deal with the dynamic temperature, tidal regime, pH, salinity and heavy metals. Among the microorganisms present in these environments, bacteria respond quickly to this dynamic conditions at both phenotypic and genotypic levels. The bacterial community forms the biofilm in such fluctuating environmental conditions for its growth and survivability. The biofilm formation ability of bacteria helps them to adhere to every substrate and operate various nutrient cycling processes. However, fluctuating environmental parameters affect their efficiency in operating various biogeochemical cycles. The current research focuses 100 on the effect of various stressors on the mangrove bacteria and thereby understanding their role in the regulation of ecosystem-level processes. In this study, a comparative analysis was done between Bacillus stercoris GST-03 (a gram-positive bacterium) and Pseudomonas balerica DST-02 (a gram-negative bacterium). B. stercoris GST-03 was found to be stress tolerating bacterium showing tolerance towards lower pH. In contrast, P. balerica DST-02 was found to be a good biofilm former. B. stercoris GST-03 shows cellulose degradation potential, which indicates it will play a crucial role in cellulose degradation in the mangrove ecosystem. In addition, B. stercoris GST-03 shows higher tolerance to temperature, salinity, heavy metals and UV compared to P. balerica DST-02. The identification of pslB and tasA in P. balerica DST-02 and B. stercoris GST-03, respectively, validates their biofilm-forming ability. The presence of genes, celA and celB validates the cellulose degradation ability of B. stercoris GST-03. The fluctuation in the environmental parameters leads to the production of ROS in both strains. ROS production was found to be minimum during the optimum growth conditions. Further, the oxidative stress-mediated DNA damage and repair mechanism were studied. The production of DNA damage products and antioxidants co-occurs. The condition at which the correlation between them imbalances leads to irreparable DNA damage in bacteria. The resulting output of the expression analysis of genes involved in the NER and SOS response pathway depicted the DNA damage at pH 9, and Pb concentration 1000 might be irreparable in B. stercoris GST-03. In contrast, DNA damage at pH 4 and 9, 1000 ppm of Pb and 200 ppm of Cd might be irreparable in P. balerica DST-02. The microcosm study revealed that B. stercoris GST-03 shows more tolerance and produces dense biofilm in the stress condition predicted for the year 2100 compared to P. balerica DST-02. The present work demonstrates the effect of various stressors on the mangrove bacteria that will help to understand the fate of the mangrove bacteria in future climate change scenarios.