People
Dr Sujatha SUBRAMONI
Research Fellow
Biofilm Biology cluster, SCELSE

Microbes mostly occur as mixed-species communities and the ways to manipulate communities of industrial, environmental or clinical significance are becoming increasingly apparent. Sujatha's current research, in the A/Prof Scott Rice's group (Biofilm Biology cluster), uses a mixed-species experimental biofilm model to decipher the basic rules that govern biofilm community structure and stability. Her research has shown that bacterial cell-cell signalling mechanisms such as quorum sensing (QS) play a major role in maintaining community composition and modulating its stress resistance. The signal-producing bacterial species that constitute as little as 1-5% of the biofilm exert substantial impact on the community physiology. Furthermore, competitive interactions between species appear to be, at least partly, QS-dependent for this model. At applied level, this study would develop novel biofilm inhibition/dispersal strategies by characterising the mechanisms of competitive interactions within the community.

Another focus of my research is the impact of invasive bacteria on a resident microbial community. Invasion of a biofilm by a new community can affect it drastically and the mechanisms that lead to a successful invasion is still unclear. To this end, the team is analysing the effect of invasion on compositional and functional stability of a defined three-species biofilm community. The group is also looking into genetic and physical aspects that facilitate invasion and modulate the response of biofilm. In addition to community biofilm biology and interspecies interactions, Sujatha's research also involves studies on quorum quenching and its effect on biofilms as well as identification of medically relevant biofilms using non-invasive biophysical techniques. She is also interested in bacterial signal sensing and response, persistence and host-pathogen interactions, as well as the use of synthetic biology as a tool to redesign existing communities for both basic research and practical applications.

Prior to working in SCELSE, Sujatha's research background in plant- and human-associated bacteria resulted from studies to understand pathogenesis and signalling mechanisms. She has used molecular biology, genetics, biochemical techniques, phenotypic assays and gene expression techniques to understand bacterial adaptation within its host and the virulence factors required for bacterial pathogenesis of opportunistic human pathogen Burkholderia cenocepacia. In particular, she focussed on the genetic analyses of ShvR, a LysR-type regulator of virulence and its target genes, and role of this regulator in influencing intracellular persistence of B. cenocepacia. Prior to these studies, Sujatha focused on certain emerging concepts such as LuxR Solo proteins, and microbial signal sensing and perception by LuxR family proteins of Pseudomonas sp. Bacterial signal perception and its role in pathogenesis and physiology has been focus of her work from her graduate studies, where she characterised a virulence regulator and a two-component regulator of Xanthomonas oryzae, a pathogen of rice.