Domonique Valle, “Understanding the Regulation of Antibiotic Secretion in Xenorhabdus szentirmaii by the Quorum-sensing Regulator LsrF”
Mentor: Madhusudan Dey, Biological Sciences
Poster #198
Antibiotic-resistant bacteria have become an increasing threat to public health worldwide. With the rapid rise in resistance to many commonly used antibiotics there is a pressing need to identify new antibiotics from new sources to combat this issue. One promising source is Xenorhabdus szentirmaii, a symbiotic bacterium residing within the intestines of the soil nematode, which naturally produces non-ribosomal peptide (NRP) antibiotics. Our research reveals that these NRPs are synthesized by 16 non-ribosomal peptide synthetases (NRPSs) encoded from the X. szentirmaii genome. Understanding the fundamental biology of these NRPSs is important for their potential commercial application. To identify genes regulating the NRPSs in X. szentirmaii, we isolated total RNAs from the log phase (when no antibiotics are produced) and the stationary phase (when antibiotics are produced) of the cell growth. Total RNA was then subjected to RNA-Seq analyses. Two top hits from these analyses are the quorum-sensing regulators lsrF and lsrG. Interestingly, we observed that the lsrF mutant of X. szentirmaii produces less antibiotics compared to its isogenic wild-type strain. These findings suggest that LsrF plays a significant role in the regulation of antibiotic secretion in X. szentirmaii.