Hawaiian Bobtail Squid Symbionts Inhibit Marine Bacteria via Production of Specialized Metabolites, Including New Bromoalterochromides BAC-D/D′
Andrea M. Suria, Karen Co Tan, Allison H. Kerwin, LUCAS GITZEL, Lydia Abini-Agbomson, Jessica M. Bertenshaw, Jaydeen Sewell, Spencer V. Nyholm, Marcy J. Balunas
Abstract
Animals that deposit eggs must protect their embryos from fouling and disease by microorganisms to ensure successful development. Although beneficial bacteria are hypothesized to contribute to egg defense in many organisms, the mechanisms of this protection are only recently being elucidated. Our previous studies of the Hawaiian bobtail squid focused on fungal inhibition by beneficial bacterial symbionts of a female reproductive gland and eggs. Herein, using genomic and chemical analyses, we demonstrate that symbiotic bacteria from this gland can also inhibit other marine bacteria in vitro . One bacterial strain in particular, Pseudoalteromonas sp. JC28, had broad-spectrum abilities to inhibit potential fouling bacteria, in part via production of novel bromoalterochromide metabolites, confirmed via genomic annotation of the associated biosynthetic gene cluster. Our results suggest that these bacterial metabolites may contribute to antimicrobial activity in this association and that such defensive symbioses are underutilized sources for discovering novel antimicrobial compounds.