Research

My research is focussed on two key questions:

(i)  How  does collective motion of microbes from the human microbiome shape the spatial organization of a microbial community. 

(ii)  How do molecular motors drive mobile cell-surface adhesins on single cells. 

A detailed description is below:

On the microbiome and collective behavior front: The human microbiome is an assemblage of diverse bacteria that interact with one another to design a community. Rapid availability of nutrition and protection from antibiotics are advantages of a specific spatial niche within a microbial community. The mechanisms that drive microbial interactions and guide the architecture of microbial communities are unclear. To study collective behavior, we studied the swarm properties of gliding bacteria from the human oral microbiome and their relevance on the spatial organization of polymicrobial communities.

On the single cell front: Bacteria that swim are driven forward by helical filaments that rotate like propellers. The number and location of filaments vary among different bacteria, yet the core mechanism remains the same. In contrast, motile but non-swimming bacteria do not have propellers, yet they achieve efficient self- propulsion over surfaces. Such movement is divided into two categories: (i) twitching and (ii) gliding. Twitching involves the extension and retraction of type IV pili and gliding involves movement of cell-surface adhesins along the length of a cell. Gliding bacteria, which have been a major focus of my research, are present in the human oral microbiome. They are important components of human polymicrobial biofilms that increase the risk of periodontal diseases. Gliding bacteria have a rotary motor that generates high torque (Shrivastava et al. Curr. Biol. 2015). Using the type IX protein secretion system (T9SS) gliding bacteria secrete cell-surface adhesins (Shrivastava et al. J. Bacteriol. 2013). With the help of the rotary motor the cell-surface adhesins move spirally along the length of a cell. A gliding bacterium works as a self-propelled screw, with a cell-surface adhesin moving along its external threads (Shrivastava et al., Biophysical J., 2016). 

Movies that best decribe my research are below. To watch the movie, please click on the links in blue.

A rotary motor found in gliding bacteria that generates high torque2.67 MB
SprB moving along a spiral track on the cell-surface6.48 MB
Three-Dimensional Track of SprB Shown Sequentially from Different Azimuth and Elevation Angles880 KB