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PhD Transfer Exam reminder – Kevin Xue -Tuesday, May 22, 2018
May 22, 2018 @ 1:00 pm - 1:30 pm
PhD Transfer Exam
Tuesday, May 22, 2018 at 1:10 pm – Earth Science Building, Room 3087
Kevin Xue (D. Christendat lab)
“Elucidating the Protocatechuate Biosynthetic Pathway in Listeria monocytogenes and its Role in Microbial Interactions”
Abstract
Listeria monocytogenes is a ubiquitous bacterial saprophyte capable of causing fatal listeriosis in mammalian hosts. L. monocytogenes boasts a high tolerance to sanitation measures and persists in food processing environments. Although much investigation of its pathogen lifestyle has been conducted, its role as a saprophyte remains poorly understood. Our lab has identified and partially characterized two operons containing genes for the biosynthesis of protocatechuate, a compound derived from plant material degradation and industrial waste (Prezioso et al. 2018 and Bonfa et al. 2013). Though other microorganisms will produce and utilize protocatechuate to generate energy or produce protocatechuate type siderophores, L. monocytogenes lacks these pathways. L. monocytogenes produces protocatechuate when the LysR type transcriptional regulator (LTTR), QuiR, induces qui1 and qui2 with its coinducer and ligand, shikimate. Shikimate supplementation leads to accelerated growth of Listeria innocua followed by rapid cell density loss. I hypothesize that L. monocytogenes generates protocatechuate, which it will exchange mutualistically with other microorganisms. Alternatively, L. monocytogenes is utilizing protocatechuate to generate a novel metabolite. The former hypothesis is supported by the loss of cell density when protocatechuate accumulates in shikimate supplied monoculture. I plan to characterize the qui1 and qui2 operons by gene deletion to study their roles in protocatechuate biosynthesis. I will also study the effect of protocatechuate on Listeria growth. Furthermore, I plan to investigate the role of protocatechuate in microbial interactions by performing co-cultured growth analysis between Listeria and other bacterial species.