Project description:Members of the Vibrionaceae family are often found associated with chitin-containing organisms and they are thought to play a major role in chitin degradation. The purpose of the present study was to determine how chitin affected the transcriptome and metabolome of two bioactive Vibrionaceae strains, Vibrio corallilyticus and Photobacterium galatheae. We focused on chitin degradation genes and secondary metabolites based on the assumption that these molecules in nature confer an advantage to the producer. Growth on chitin caused up-regulation of genes related to chitin metabolism and of genes potentially involved in host colonization and/or infection. The expression of genes involved in secondary metabolism was also significantly affected by growth on chitin, in one case being thirty-four folds upregulated. This was reflected in the metabolome, where the antibiotics andrimid and holomycin were produced in higher amounts on chitin. Interestingly, in cultures of P. galatheae grown on chitin we detected high amounts of the biogenic amine phenylethylamine. Overall, these results suggest that both V. coralliilyticus and P. galatheae have a specific lifestyle for growth on chitin, and that the secondary metabolites they produce are likely to play a crucial role during chitin colonization.
Project description:Members of the Vibrionaceae family are often found associated with chitin-containing organisms and they are thought to play a major role in chitin degradation. The purpose of the present study was to determine how chitin affected the transcriptome and metabolome of two bioactive Vibrionaceae strains, Vibrio corallilyticus and Photobacterium galatheae. We focused on chitin degradation genes and secondary metabolites based on the assumption that these molecules in nature confer an advantage to the producer. Growth on chitin caused up-regulation of genes related to chitin metabolism and of genes potentially involved in host colonization and/or infection. The expression of genes involved in secondary metabolism was also significantly affected by growth on chitin, in one case being thirty-four folds upregulated. This was reflected in the metabolome, where the antibiotics andrimid and holomycin were produced in higher amounts on chitin. Interestingly, in cultures of P. galatheae grown on chitin we detected high amounts of the biogenic amine phenylethylamine. Overall, these results suggest that both V. coralliilyticus and P. galatheae have a specific lifestyle for growth on chitin, and that the secondary metabolites they produce are likely to play a crucial role during chitin colonization.
Project description:The marine bacterium Photobacterium galatheae S2753 produces a group of cyclodepsipeptides, solonamides, which impede the virulence but not the survival of Staphylococcus aureus. Besides the invaluable antivirulence activity, little is known about the biosynthesis and physiological function of solonamides in the native producer. This study generated a solonamides-deficient mutant, Δsol, by in-frame deleting the sol gene, thereby identifying the core gene for solonamides biosynthesis. By annotation from antiSMASH, the biosynthetic pathway of solonamides in S2753 was also proposed. Mass spectrometry analysis of cell extracts found that deficiency of solonamides production influenced the production of several novel lipids, but not the overall secondary metabolite profile. Physiological comparison between Δsol and wild-type S2753 demonstrated that growth dynamics and biofilm formation of both strains were similar; however, Δsol displayed reduced swimming rings as compared to the wild-type. The swimming ring size of Δsol was restored to the level of wild-type strain by adding solonamide B, indicating that solonamide B influences regulate the swimming behavior of P. galatheae S2753. Proteomic analysis of the Δsol and wild-type found that eliminating solonamides influenced many cellular processes, including swimming-related proteins and that solonamides trigger the motility of S2753 likely by adjusting the cellular cyclic di-GMP concentration. In conclusion, our results revealed the biosynthetic pathway of solonamides and their ecological benefits to P. galatheae S2753 by enhancing the swimming velocity, likely by altering the motile physiology.