Special Biology Seminar

Abstract:

My seminar will be divided into two parts. First, I will talk about my PhD work that features the fascinating world of surface attached microbial communities called biofilms. Second, I will talk about my current post-doctoral work and future research I will pursue in my own lab that aims to establish a new research paradigm focusing on the pathogen-microbiome-plant interaction system. Both stories highlight my strong interest in understanding mechanisms of microbial signaling during disease development. My future lab will tackle unanswered questions in plant biology that have the potential to drive practical and sustainable solutions for plant health using engineered microbial communities.

Biofilms are ubiquitous and are found in a variety of natural and clinical environments; be it on the surface of rocks, in the lungs of patients with cystic fibrosis or on plant leaves. While much of the early work in microbiology relied on studying bacteria in planktonic pure cultures because of the then traditional view of bacteria as simple free-floating organisms, we have now come to appreciate that bacteria prefer to attach to surfaces. How does the transition from free-swimming to biofilm mode occur? In my talk, I will discuss three key sequential events that are needed for this switch: surface sensing, signal transmission and a cellular response. I will present a molecular mechanism that highlights the importance of the type 4 pili (TFP) cellular machinery and the second messenger dinucleotide molecule, cyclic-di-GMP. I will discuss the role of an extracellular force sensing protein and the signaling pathway by which this external surface signal is transmitted intracellularly to regulate cyclic-di-GMP levels, thereby regulating the switch to a biofilm lifestyle.

Biofilms are often polymicrobial in nature consisting of commensal, pathogenic and symbiotic species, which are commonly found in plants. How do plants control the level and composition of their associated microbiomes in order to maximize the benefits of useful bacteria and to prevent the overgrowth of harmful bacterial species? Does pathogen invasion alter the community structure and signaling networks? Future work in the Webster lab will explore these unresolved fundamental questions by considering the microbiome as an integral part of the plant-pathogen interactions.