Background: Competition between bacteria for habitat and resources is very common in the natural environment and is considered to be a selective force for survival. Many strains of the genus Pseudoalteromonas were confirmed to produce bioactive compounds that provide those advantages over their competitors. In our previous study, P. flavipulchra JG1 was found to synthesize a Pseudoalteromonas flavipulchra antibacterial Protein (PfaP) with L-amino acid oxidase activity and five small chemical compounds, which were the main competitive agents of the strain. In addition, the genome of this bacterium has been previously sequenced as Whole Genome Shotgun project (PMID: 22740664). In this study, more extensive genomic analysis was performed to identify specific genes or gene clusters which related to its competitive feature, and further experiments were carried out to confirm the physiological roles of these genes when competing with other microorganisms in marine environment.
Results: The antibacterial protein PfaP may also participate in the biosynthesis of 6-bromoindolyl-3-acetic acid, indicating a synergistic effect between the antibacterial macromolecule and small molecules. Chitinases and quorum quenching enzymes present in P. flavipulchra, which coincide with great chitinase and acyl homoserine lactones degrading activities of strain JG1, suggest other potential mechanisms contribute to antibacterial/antifungal activities. Moreover, movability and rapid response mechanisms to phosphorus starvation and other stresses, such as antibiotic, oxidative and heavy metal stress, enable JG1 to adapt to deleterious, fluctuating and oligotrophic marine environments.
Conclusions: The genome of P. flavipulchra JG1 exhibits significant genetic advantages against other microorganisms, encoding antimicrobial agents as well as abilities to adapt to various adverse environments. Genes involved in synthesis of various antimicrobial substances enriches the antagonistic mechanisms of P. flavipulchra JG1 and affords several admissible biocontrol procedures in aquaculture. Furthermore, JG1 also evolves a range of mechanisms adapting the adverse marine environment or multidrug rearing conditions. The analysis of the genome of P. flavipulchra JG1 provides a better understanding of its competitive properties and also an extensive application prospect.