Examining the effects of the deletion of flhC and flhC2 genes of B. unamae flhC and flhC2 on motility and exopolysaccharide production.
Mentor:Michelle Lum, Associate Professor, Loyola Marymount University
The rhizospheric and endophytic nature of B. unamae and its capability to elevate levels of nitrogen through nitrogen-fixation allow for its beneficial associations with crops like maize, sugarcane, and tomato. Our study focuses on the genes associated with the ability of B. unamae to interact and form relationships with the roots of these plants. Previous research in the lab identified flhC1 as important for motility and exopolysaccharide production. Other studies have shown that flhC is involved in gene regulation, specifically as a flagellar transcriptional activator. To confirm our findings and determine whether a second copy of the flhC gene, flhC2, is also important, we generated B. unamae mutants deleted in flhC1 (ΔflhC1) and flhC2 (ΔflhC2). To do this, first vectors that could be used to generate the deletions were constructed through PCR and cloning methods. The constructs were then introduced into B. unamae by conjugation and potential mutants selected and confirmed by PCR. Our results show that ΔflhC1 has a similar phenotype as what we had seen in the flhC1 transposon mutant, exhibiting low motility and an increased mucoid phenotype, indicative of altered exopolysaccharide production. However, ΔflhC2 does not display differences in motility from wild type B. unamae on 0.3% agar media. We are doing further investigation of the exopolysaccharide produced by B. unamae in comparison to that of ΔflhC1 and ΔflhC2, and we are also in the process of complementing the deletions to definitively demonstrate that flhC1 and flhC2 are involved in the phenotypic results of the mutants. The relationship between the deletion mutants and production of exopolysaccharide is of importance because that trait can play a critical role in bacterial-host interactions. We hope through our findings we broaden the knowledge behind the mechanisms of bacteria, in this particular case B. unamae, to associate with plants.