Prem Krishnan Raghupathi

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Biofilms are ubiquitous in diverse environments, and are considered as one of the main evolutionary bacterial pre-ingestion adaption against protozoan grazing. Multiple species of both eukaryotic and prokaryotic microbes, including human pathogens, reside within these biofilms. The inter-specific bacterial interactions are highly important for the dynamics and productivity in multispecies biofilm; however, currently the functional mechanisms of these interactions are poorly described. Furthermore, the resistance to protozoan digestion may facilitate survival and proliferation of pathogenic bacteria in non-host environments and also serve as an evolutionary precursor of pathogenicity as intracellular processing of bacteria by protozoa maybe similar to that observed in mammalian cells.

Presently there is little knowledge about the underlying mechanisms regarding the association of bacteria and protozoa within the biofilm environment. Many studies carried out in different settings to study pathogenic interaction in biofilms are done with single or two species but less is known about the interactions in a multispecies setting. There is a need to assess the impact of protozoa on mixed-species biofilms, which represent the predominant lifestyle in most ecosystems. Free-living protozoa also play a role in the selection of bacterial virulence traits and adaptation to survival in macrophages and protozoan models can be used to elucidate the survival traits and further contribute to transmission and prevalence of pathogenic strains.

Our hypothesis is that bacteria can protect themselves from grazing protozoan through biofilm forming mechanisms. In multispecies biofilms settings, the synergistic interactions between strains play vital role in providing the bacteria with a biofilm barrier. The general aim of this project is to elucidate the mechanisms underlying settling and persistence of pathogens in biofilm and to identify gene targets that facilitate inter-specific synergistic and antagonistic effects.

This will facilitate the understanding of the interactions of pathogens within a multi-species setting. The presence of protozoa will further provide scope to understand bacterial adaptations to form biofilm and the protozoan preference during grazing. Protozoa will serve as a tool to understand pathogenic escape during phagocytosis and to evaluate the effect of different selection pressures involved in the environment that actually exist for the opportunistic pathogens to tend to virulent state.