Past Research Activities-

PhD Research Work-

For my PhD thesis titled “Heterogeneity among Vibrio cholerae O1 environmental strains in relation to SXT-ICEs and CTX genetic element" I worked under the guidance of Dr. Durg V. Singh at the Institute of Life Sciences, Bhubaneswar. The work primarily focused on understanding the genetic diversity of the environmental strains of Vibrio cholerae. Specifically, we studied two important genetic loci; the CTX genetic element encoding the cholera toxin, and the SXT element involved in transferring drug resistance genes. The study highlighted the role of environmental strains as reservoirs of virulence and antibiotic resistance genes, which under different circumstances move from one bacterium to other via horizontal gene transfer (HGT) mechanisms (Mohapatra et al., 2010 ). During the study, we discovered unique strains of V. cholerae, carrying two distinct bacteriophages, encoding for the classical and El Tor type of CTXΦs on their two chromosomes respectively (Mohapatra et al., 2011 ). These hybrid strains have major evolutionary significance in addressing the emergence of huge diversity among pathogenic strains of V. cholerae. I also studied different clinical strains isolated during cholera epidemics to understand the dynamics of their emergence by comparing to strains isolated from various geographic locations (Mohapatra et al., 2007; 2009; 2015). Apart from my primary work, fruitful collaborations with my colleagues in the lab resulted in successful publications dealing with various aspects of V. cholerae diversity and CTXΦ biology (Mantri et al., 2006; Mohapatra et al., 2008; Mantri et al., 2010; Mantri et al., 2010).

Postdoctoral Research Work-

In 2009, I started my first postdoctoral work at the University of Kansas Medical Center, USA in the laboratory of  Prof. Indranil Biswas. The work involved various aspects of Streptococcus mutans genetics, specifically focusing on the modulation of virulence gene expression by different two-­component signal transduction systems. We extensively studied the orphan response regulator CovR, which is the major modulator of virulence genes in S. mutans (Dmitriev et al., 2011; Khara et al., 2018).  We  showed  that  histone-­like  proteins  (Hlp)  in  the  bacteria  often  silence horizontally acquired genes; however, proteins like CovR can overcome this silencing and can initiate transcription from such genes (Biswas and Mohapatra, 2012). We studied the phosphorylation pathways in the two-component system LiaSR and its role in the transcriptional regulation of various stress response related genes (Shankar et al., 2015). I also worked on a TetR family transcription repressor to understand its effects on the genes acquired by horizontal gene transfer (Chattoraj et al., 2011).

In 2012,  I  moved  to  the  CNRS- Interdisciplinary  Research  Institute  at the University of Lille,  France, for my second postdoctoral work in the Bacterial Cell Biology and Comparative Systems Biology lab headed by Dr. Emanuele Biondi. There I worked in the area of bacterial cell cycle regulation mechanisms using the model Alphaproteobacterium Caulobacter crescentus. My work specifically involved in understanding the mechanisms used by one of the cell cycle master regulators GcrA to precisely coordinate the expression of various genes. Our study established  a  distinct  epigenetic  module  (GcrA-­CcrM)  involved  in  the  cell  cycle  progression  in Caulobacter (Fioravanti et al., 2013; Mohapatra et al., 2014). As GcrA is a unique transcription factor, our investigation indicated its interaction with the RNA polymerase, which is important in the transcriptional regulation of the GcrA regulon. Interestingly, we also showed that GcrA mediated epigenetic regulation is required for the spatial transcription and assembly of the cytoskeletal protein crescentin in the Caulobacter cell (Mohapatra et al., 2020).

After returning to India, I briefly worked at the CSIR- Centre for Cellular and Molecular Biology (CCMB), and DBT- Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad as Research Associate. My work in the Laboratory of Bacterial Genetics, CDFD, headed by Dr. J. Gowrishankar was in the project "Role of R-loops (RNA-DNA hybrids) in generation of transcription-replication conflicts in Escherichia coli".