Limits...
Strain identification and quorum sensing inhibition characterization of marine-derived Rhizobium sp. NAO1

View Article: PubMed Central - PubMed

ABSTRACT

A novel strategy for combating pathogens is through the ongoing development and use of anti-quorum sensing (QS) treatments such as therapeutic bacteria or their anti-QS substances. Relatively little is known about the bacteria that inhabit the open ocean and of their potential anti-pathogenic attributes; thus, in an initiative to identify these types of therapeutic bacteria, planktonic microbes from the North Atlantic Ocean were collected, isolated, cultured and screened for anti-QS activity. Screening analysis identified one such strain, Rhizobium sp. NAO1. Extracts of Rhizobium sp. NAO1 were identified via ultra-performance liquid chromatography (UPLC) analysis. They were shown to contain N-acyl homoserine lactone (AHL)-based QS analogues (in particular, the N-butyryl homoserine lactone (C4-AHL) analogue) and could disrupt biofilm formation by Pseudomonas aeruginosa PAO1. QS inhibition was confirmed using confocal scanning laser microscopy and growth curves, and it was shown to occur in a dose-dependent manner without affecting bacterial growth. Secondary metabolites of Rhizobium sp. NAO1 inhibited PAO1 pathogenicity by downregulating AHL-mediated virulence factors such as elastase activity and siderophore production. Furthermore, as a result of biofilm structure damage, the secondary metabolite products of Rhizobium sp. NAO1 significantly increased the sensitivity of PAO1 to aminoglycoside antibiotics. Our results demonstrated that Rhizobium sp. strain NAO1 has the ability to disrupt P. aeruginosa PAO1 biofilm architecture, in addition to attenuating P. aeruginosa PAO1 virulence factor production and pathogenicity. Therefore, the newly identified ocean-derived Rhizobium sp. NAO1 has the potential to serve as a QS inhibitor and may be a new microbial resource for drug development.

No MeSH data available.


Related in: MedlinePlus

Biofilm inhibition assay. (a) A, P. aeruginosa biofilm (positive control); B, M63 broth (negative control); C, D and E, biofilm treated with 5% supernatant, 5% aqueous extract and 0.5% organic extract of QSI, respectively. (b) Biofilm production of P. aeruginosa cell culture (50 µl) in the presence of QSI supernatant (1%, 3%, 5%), aqueous extract (5%), organic extract (0.5%), furanone (10 µM), QSI culture (50 µl) and methanol (0.5%). Asterisks indicate a statistically significant difference (**p < 0.01) between experimental groups and control (P. aeruginosa culture).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5383856&req=5

RSOS170025F2: Biofilm inhibition assay. (a) A, P. aeruginosa biofilm (positive control); B, M63 broth (negative control); C, D and E, biofilm treated with 5% supernatant, 5% aqueous extract and 0.5% organic extract of QSI, respectively. (b) Biofilm production of P. aeruginosa cell culture (50 µl) in the presence of QSI supernatant (1%, 3%, 5%), aqueous extract (5%), organic extract (0.5%), furanone (10 µM), QSI culture (50 µl) and methanol (0.5%). Asterisks indicate a statistically significant difference (**p < 0.01) between experimental groups and control (P. aeruginosa culture).

Mentions: Pseudomonas aeruginosa PAO1 can form biofilms, which is a partially QS-dependent process. Therefore, the ability of extracts from isolate strain Rhizobium sp. NAO1 to inhibit biofilm formation by P. aeruginosa PAO1 was investigated. Figure 2b presents quantitative analysis of PAO1 biofilm inhibition. We found that addition of QSI cell culture (50 µl), QSI supernatant (1%, 3% and 5%), aqueous extract (5%) or organic extract (0.5%) to PAO1 reduced biofilm formation by 32.0% (QSI), 65.1%, 72.3% and 75.9% (three QSI supernatants), 77.9% (aqueous extract) and 72.3% (organic extract). Inhibition by different percentages of QSI supernatant occurred in a dose-dependent manner. The highest reduction in the amount of biofilm was 77.9%, which was caused by the 5% aqueous extract. Visualization by light microscopy also revealed a considerable reduction in biofilm intensity (figure 2a). The chromatogram results showed that the supernatant from strain Rhizobium sp. NAO1 likely contained analogues of the N-butyryl homoserine lactone (C4-AHL) compounds of P. aeruginosa PAO1 (figure 3). Overall, the results indicated that N-acyl homoserine lactone (AHL) analogues secreted by Rhizobium sp. NAO1 were partially responsible for the inhibition of biofilm formation.Figure 2.


Strain identification and quorum sensing inhibition characterization of marine-derived Rhizobium sp. NAO1
Biofilm inhibition assay. (a) A, P. aeruginosa biofilm (positive control); B, M63 broth (negative control); C, D and E, biofilm treated with 5% supernatant, 5% aqueous extract and 0.5% organic extract of QSI, respectively. (b) Biofilm production of P. aeruginosa cell culture (50 µl) in the presence of QSI supernatant (1%, 3%, 5%), aqueous extract (5%), organic extract (0.5%), furanone (10 µM), QSI culture (50 µl) and methanol (0.5%). Asterisks indicate a statistically significant difference (**p < 0.01) between experimental groups and control (P. aeruginosa culture).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383856&req=5

RSOS170025F2: Biofilm inhibition assay. (a) A, P. aeruginosa biofilm (positive control); B, M63 broth (negative control); C, D and E, biofilm treated with 5% supernatant, 5% aqueous extract and 0.5% organic extract of QSI, respectively. (b) Biofilm production of P. aeruginosa cell culture (50 µl) in the presence of QSI supernatant (1%, 3%, 5%), aqueous extract (5%), organic extract (0.5%), furanone (10 µM), QSI culture (50 µl) and methanol (0.5%). Asterisks indicate a statistically significant difference (**p < 0.01) between experimental groups and control (P. aeruginosa culture).
Mentions: Pseudomonas aeruginosa PAO1 can form biofilms, which is a partially QS-dependent process. Therefore, the ability of extracts from isolate strain Rhizobium sp. NAO1 to inhibit biofilm formation by P. aeruginosa PAO1 was investigated. Figure 2b presents quantitative analysis of PAO1 biofilm inhibition. We found that addition of QSI cell culture (50 µl), QSI supernatant (1%, 3% and 5%), aqueous extract (5%) or organic extract (0.5%) to PAO1 reduced biofilm formation by 32.0% (QSI), 65.1%, 72.3% and 75.9% (three QSI supernatants), 77.9% (aqueous extract) and 72.3% (organic extract). Inhibition by different percentages of QSI supernatant occurred in a dose-dependent manner. The highest reduction in the amount of biofilm was 77.9%, which was caused by the 5% aqueous extract. Visualization by light microscopy also revealed a considerable reduction in biofilm intensity (figure 2a). The chromatogram results showed that the supernatant from strain Rhizobium sp. NAO1 likely contained analogues of the N-butyryl homoserine lactone (C4-AHL) compounds of P. aeruginosa PAO1 (figure 3). Overall, the results indicated that N-acyl homoserine lactone (AHL) analogues secreted by Rhizobium sp. NAO1 were partially responsible for the inhibition of biofilm formation.Figure 2.

View Article: PubMed Central - PubMed

ABSTRACT

A novel strategy for combating pathogens is through the ongoing development and use of anti-quorum sensing (QS) treatments such as therapeutic bacteria or their anti-QS substances. Relatively little is known about the bacteria that inhabit the open ocean and of their potential anti-pathogenic attributes; thus, in an initiative to identify these types of therapeutic bacteria, planktonic microbes from the North Atlantic Ocean were collected, isolated, cultured and screened for anti-QS activity. Screening analysis identified one such strain, Rhizobium sp. NAO1. Extracts of Rhizobium sp. NAO1 were identified via ultra-performance liquid chromatography (UPLC) analysis. They were shown to contain N-acyl homoserine lactone (AHL)-based QS analogues (in particular, the N-butyryl homoserine lactone (C4-AHL) analogue) and could disrupt biofilm formation by Pseudomonas aeruginosa PAO1. QS inhibition was confirmed using confocal scanning laser microscopy and growth curves, and it was shown to occur in a dose-dependent manner without affecting bacterial growth. Secondary metabolites of Rhizobium sp. NAO1 inhibited PAO1 pathogenicity by downregulating AHL-mediated virulence factors such as elastase activity and siderophore production. Furthermore, as a result of biofilm structure damage, the secondary metabolite products of Rhizobium sp. NAO1 significantly increased the sensitivity of PAO1 to aminoglycoside antibiotics. Our results demonstrated that Rhizobium sp. strain NAO1 has the ability to disrupt P. aeruginosa PAO1 biofilm architecture, in addition to attenuating P. aeruginosa PAO1 virulence factor production and pathogenicity. Therefore, the newly identified ocean-derived Rhizobium sp. NAO1 has the potential to serve as a QS inhibitor and may be a new microbial resource for drug development.

No MeSH data available.


Related in: MedlinePlus