Archaeal stress response:

Microbial species cope with stress conditions employing a variety of molecular players, e.g., heat shock protein repertoire, toxin-antitoxin systems, transcriptional regulators, metabolic pathways, etc. Although the pathways of cellular response to different stressors (pH, temperature, oxygen, nutrients depletion, oxidative stress, and osmolarity) have been addressed sufficiently in the domain of bacteria, information regarding the molecular players remains elusive in the third domain of life, namely archaea. Our research group, therefore, aims at understanding the fate of stress-related proteins under conditions of stress, which includes identification, characterization, and analysis of the mode of regulation of stress-related proteins and their targets. Using a thermoacidophilic crenarchaeon Sulfolobus acidocaldarius as our model organism, we have demonstrated the important role of heat shock proteins, toxin-antitoxin systems, and protein secretion pathway in archaeal stress management (Current Microbiol 2017, BBA Biomembrane 2018, BBRC 2020, FEBS Journal 2022, Fron. Mol BioSci 2022). Understanding the mechanics of archaeal molecular machines can provide useful insights into how life has evolved for the past 3.5 billion years. We intend to continue this research to further understand how ancient molecular machines help microbes to adapt and evolve at the molecular level. Since archaea can sustain extreme limiting conditions, withstanding different kinds of stresses, we also aim to get a thorough idea about the effect of different types of stressors on archaeal cells at the transcriptomic and proteomic levels. We want to study the fate of stress-related proteins under conditions of stress, which includes identification, characterization, and analysis of the mode of regulation of stress-related proteins and their targets. Therefore, the current research in our lab is concerned with understanding the effect of heat stress on archaea in regard to different molecular chaperones. In addition, our recent venture is to study the role of toxin-antitoxin systems in stress adaptation in archaea.

​

Stress adaptation of environmental microbes:

Microbial species aren’t often found alone in the natural environment, but rather in complex communities containing dozens to hundreds of other species. These species affect one another in many ways. Species can harm one another by producing antibiotics, stabbing one another and injecting toxins, or simply consuming resources that others require. Microbes can also impact one another positively. They can, for example, degrade antibiotics and detoxify the environment, secrete iron-scavenging molecules that allow other species to take up iron, or excrete metabolic byproducts that others can consume. Anthropic activities further complicate these processes through the selective enrichment of microbial communities in environment. It is therefore important to gain insights into the role of microbes and their interactions in the backdrop of human intervention. Hence, we also work on microbe-microbe and microbe-plant interactions in two contrasting ecosystems, i.e., Sundarban mangrove and Darjeeling tea estates. In the last century, mangrove ecosystems became increasingly threatened due to changes in land usage patterns, different biotic pressure, natural calamities, and, finally, anthropogenic influences. Microbes being an integral component of mangrove ecosystems, play a significant role in ecosystem function. However, due to increasing human intervention, mangrove microbial communities face a variety of challenges that drive changes in both microbial and ecosystem ecology. In our laboratory, we are primarily interested in gaining insight into the effect of various stresses [salinity, osmolarity, and anthropogenic pollutants such as potentially toxic elements (PTEs) and polyaromatic hydrocarbons (PAHs), etc.] on mangrove microbial communities. In the last couple of years, my research group has been successful in understanding how various anthropic factors influence the microbiome structure and function (Microbiol Ecol 2015, World J Microbiol Biotechnol 2015, Archaea 2015, BMC Microbiol 2015, Genomics data 2016, STOTEN 2017, Env Sci Pol Res 2018, STOTEN 2019, Ecotox Environ Safety 2020, Chemosphere 2022). Moreover, we have successfully demonstrated that microorganisms adapt by altering their metabolic profiles to cope with the changing environmental conditions in the mangrove ecosystem. Our research work opens up a new dimension to explore the long-term implication of ongoing pollution in the Sundarban mangrove and hints towards earnest consideration to develop policies for restricting the increase in anthropogenic loads (i.e., PTEs and PAHs) arising from different sources in the estuaries of Sundarban. In the tea ecosystem, we aimed at identifying the role of plant-microbe interaction as an adaptive strategy for the resident microbial communities. Our research has demonstrated that the ‘rhizosphere effect’ plays a crucial role in the maintenance of the tea rhizosphere microbiome in the Darjeeling region (Front Microbiol 2017, Sci. Reports 2021, Environ Microbiol 2021). Selective enrichment of microorganisms and plant-microbe interaction in such a unique ecosystem plays a crucial role in developing the robust stress adaptation capacity of the resident microbial communities. Our research has potential implications for the development of a sustainable ecosystem and can directly benefit society as we are in the midst of the greatest transition from chemical to organic practices for long-term sustenance of the environment.  We intend to further explore the microbiome in human impacted ecosystem to understand the adaptation and evolution of microbes in a community setting.