Abstract
BackgroundCompetition 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.ResultsThe 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.ConclusionsThe 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.
Highlights
Competition between bacteria for habitat and resources is very common in the natural environment and is considered to be a selective force for survival
We have found that the P. flavipulchra genome contains several genes and gene clusters that might be involved in the production of inhibitory compounds against pathogens and competitors in the marine environment
The P. flavipulchra JG1 genome is larger than that of the five other Pseudoalteromonas strains whose genomic sequences have been published in the IMG database: P. tunicata D2 (Gi05080), P. haloplanktis TAC125 (Gc00289), P. atlantica T6c (Gc00395) and two Pseudoalteromonas strains TW-7 (Gi01432) and SM9913 (Gc01563)
Summary
Competition between bacteria for habitat and resources is very common in the natural environment and is considered to be a selective force for survival. 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. Analysis of its complete genome sequence revealed that several genes and gene clusters were involved in the production of inhibitory compounds that were associated with its successful persistence and competition on marine surfaces [8]. Strain JG1 was shown to synthesize the putative L-amino acid oxidase named Pseudoalteromonas flavipulchra antibacterial Protein (PfaP) and 5 small molecular compounds with antibacterial activity. These compounds were identified as p-hydroxybenzoic acid, trans-cinnamic acid, 6bromoindolyl-3-acetic acid, N-hydroxybenzoisoxazolone and 2′-deoxyadenosine. The inhibitory properties of P. flavipulchra JG1 against fish pathogens indicate that the strain or its products could be utilized as biocontrol agent(s) in aquaculture
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