Para-Aminobenzoic Acid, Calcium, and c-di-GMP Induce Formation of Cohesive, Syp-Polysaccharide-Dependent Biofilms in Vibrio fischeri

• DOI: 10.1128/mbio.02034-21
• Publication Date: 2021-10-05T08:34:41Z
• Authors: Courtney N. Dial; Lauren Speare; Garrett C. Sharpe; Scott M. Gifford; Alecia N. Septer; Karen L. Visick
• Keywords: Stringent response; Wild type

The marine bacterium Vibrio fischeri efficiently colonizes its symbiotic squid host, Euprymna scolopes, by producing a transient biofilm dependent on the symbiosis polysaccharide (SYP). In vitro, however, wild-type strain ES114 fails to form SYP-dependent biofilms. Instead, genetically engineered strains, such as those lacking negative regulator BinK, have been developed study this phenomenon. Historically, V. has grown using LBS, complex medium containing tryptone and yeast extract; supplementation with calcium is required induce formation binK mutant. Here, through our discovery that extract inhibits formation, we uncover signals underlying mechanisms control formation. contrast inability unsupplemented mutant formed cohesive, colony biofilms tTBS, modified LBS lacks extract. Moreover, became proficient when in tTBS supplemented both vitamin para-aminobenzoic acid (pABA); neither molecule alone was sufficient, indicating phenotype relies coordinating two cues. pABA/calcium also inhibited bacterial motility. Consistent these phenotypes, cells were enriched transcripts for biofilm-related genes predicted diguanylate cyclases, which produce second messenger cyclic-di-GMP (c-di-GMP). They exhibited elevated levels of c-di-GMP, observed phosphodiesterase overproduction abrogated partially rescued This work thus provides insight into conditions, signals, processes promote fischeri. IMPORTANCE Bacteria integrate environmental regulate gene expression protein production adapt their surroundings. One behavioral adaptation biofilm, can adherence colonization provide protection against antimicrobials. Identifying trigger mechanism(s) action remain important challenging areas investigation. determined extract, commonly used growth bacteria laboratory culture, fischeri, model investigating host-relevant Omitting from led identification an unusual signal, (pABA), added together could pABA increased concentrations messenger, necessary but not sufficient advances understanding signal integration controlling