Antimicrobial properties and chemical profiling of the acessory nidamental gland in the squid Euprymna scolopes

The Hawaiian bobtail squid, Euprymna scolopes, has served as a model for studying host-microbe interactions such as the light organ symbiosis with the bioluminescent bacterium Vibrio fischeri. We have previously characterized the composition of the bacterial consortium found in the accessory nidamental gland (ANG), part of the reproductive system of the female host. Our continued research supports the hypothesis that bacteria from the ANG are deposited into the egg jelly coat (JC) where they produce antimicrobial secondary metabolites that protect eggs from harmful microorganisms and degradation throughout their embryonic period, during which time they are physically unprotected. Given that the ANG symbiosis has naturally evolved to select for bacteria with antimicrobial properties, this provides a source of secondary metabolites that are more likely to have potent antibiotic activity. Bacterial isolates from the ANG and JC have been cultured and extracted, and have shown potent antibacterial activity against a suite of marine and human pathogens. Chemical networking, activity-guided isolation, compound identification, and biological activity of isolates will be discussed. Future studies will involve investigations of the mechanism(s) of antimicrobial activity and medicinal chemistry to probe structure-activity relationships.