Effect of Soybean Coumestrol on Bradyrhizobium japonicum Nodulation Ability, Biofilm Formation, and Transcriptional Profile

Lee, Hae-In; Lee, Jin Hwan; Park, Ki Hun; Sangurdekar, Dipen; Chang, Woo Suk

doi:10.1128/aem.07336-11

Cited by 45 publications

(24 citation statements)

References 57 publications

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“…These phenolic compounds are believed to be promising candidates as complementary therapeutics (6), since they can modify bacterial behavior by affecting bacterial motility (7,8,58), surface adhesion (9), biofilm formation (7,10), quorum sensing (11), and production of virulence determinants (12,13). Traditional medicinal approaches owe their significance to the bioactive components that have their origin in plant sources, and many are associated with routine dietary habits.…”

mentioning

confidence: 99%

Polyphenolic Extract from Maple Syrup Potentiates Antibiotic Susceptibility and Reduces Biofilm Formation of Pathogenic Bacteria

Maisuria

Hosseinidoust

Tufenkji

2015

Appl Environ Microbiol

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Phenolic compounds are believed to be promising candidates as complementary therapeutics. Maple syrup, prepared by concentrating the sap from the North American maple tree, is a rich source of natural and process-derived phenolic compounds. In this work, we report the antimicrobial activity of a phenolic-rich maple syrup extract (PRMSE). PRMSE exhibited antimicrobial activity as well as strong synergistic interaction with selected antibiotics against Gram-negative clinical strains of Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa. Among the phenolic constituents of PRMSE, catechol exhibited strong synergy with antibiotics as well as with other phenolic components of PRMSE against bacterial growth. At sublethal concentrations, PRMSE and catechol efficiently reduced biofilm formation and increased the susceptibility of bacterial biofilms to antibiotics. In an effort to elucidate the mechanism for the observed synergy with antibiotics, PRMSE was found to increase outer membrane permeability of all bacterial strains and effectively inhibit efflux pump activity. Furthermore, transcriptome analysis revealed that PRMSE significantly repressed multiple-drug resistance genes as well as genes associated with motility, adhesion, biofilm formation, and virulence. Overall, this study provides a proof of concept and starting point for investigating the molecular mechanism of the reported increase in bacterial antibiotic susceptibility in the presence of PRMSE. Gram-negative and Gram-positive bacteria colonize surfaces in health care settings, on indwelling medical devices, and even on live tissue, leading to infections that often are treated with antibiotic therapy. However, two major factors complicate the effectiveness of antibiotic treatments, namely, (i) the rising number of antibiotic-resistant bacteria and (ii) the formation of biofilms. These complications lead to increased patient morbidity, increased costs of treatment, and higher rates of hospitalization (1, 2). Antibiotic resistance is the inevitable evolutionary survival mechanism of bacteria, and it is aggravated by the overuse of antibiotics in the medical and farming industries. Bacterial biofilms are structured, surface-associated microbial communities, protected by a self-produced matrix of extracellular polymeric substances, and are the most common mode of bacterial growth. Formation of biofilms complicates the treatment of infections, because bacteria in biofilm mode generally are very persistent, requiring considerably higher doses of antibiotics for treatment than planktonic bacteria (3). High antibiotic doses disturb the body's microbiome, putting the patient's health at risk, as well as increasing the potential for development of antibiotic-resistant strains (4). The reduced effectiveness of current therapies and a declining repertoire of clinically useful drugs motivate research for the identification of novel molecules endowed with antimicrobial and/or antibiofilm properties.Many plants synthesize aromatic substances, most of which ar...

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confidence: 99%

Polyphenolic Extract from Maple Syrup Potentiates Antibiotic Susceptibility and Reduces Biofilm Formation of Pathogenic Bacteria

Maisuria

Hosseinidoust

Tufenkji

2015

Appl Environ Microbiol

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“…A quantitative biofilm assay was performed in polystyrene 96-well microtiter plates as described previously [36,37]. Briefly, B. japonicum cells were harvested from 10 ml of mid-log phase culture by centrifugation at 8,000 × g for 5 min.…”

Section: Methodsmentioning

confidence: 99%

“…Soybean seeds for the nodulation assay were surface-sterilized and germinated as described previously [37]. The sterilized seeds were transferred into plastic plant growth pouches (Mega International) and inoculated with 1 ml of the cell suspension (OD 600 = 0.1; ca.…”

Section: Methodsmentioning

confidence: 99%

Effects of Indole-3-Acetic Acid on the Transcriptional Activities and Stress Tolerance of Bradyrhizobium japonicum

et al. 2013

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A genome-wide transcriptional profile of Bradyrhizobium japonicum, the nitrogen-fixing endosymbiont of the soybean plant, revealed differential expression of approximately 15% of the genome after a 1 mM treatment with the phytohormone indole-3-acetic acid (IAA). A total of 1,323 genes were differentially expressed (619 up-regulated and 704 down-regulated) at a two-fold cut off with q value ≤ 0.05. General stress response genes were induced, such as those involved in response to heat, cold, oxidative, osmotic, and desiccation stresses and in exopolysaccharide (EPS) biosynthesis. This suggests that IAA is effective in activating a generalized stress response in B. japonicum. The transcriptional data were corroborated by the finding that stress tolerance of B. japonicum in cell viability assays was enhanced when pre-treated with 1 mM IAA compared to controls. The IAA treatment also stimulated biofilm formation and EPS production by B. japonicum, especially acidic sugar components in the total EPS. The IAA pre-treatment did not influence the nodulation ability of B. japonicum. The data provide a comprehensive overview of the potential transcriptional responses of the symbiotic bacterium when exposed to the ubiquitous hormone of its plant host.

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“…Nodulation assay was performed by the method described in the previous study (Lee et al, 2012). Bacterial cultures for nodulation assay were grown to an OD 600 of 1 at 30°C at 200 rpm and diluted to an OD 600 of 0.1 in half-strength Broughton and Dilworth (B&D) media (Broughton and Dilworth, 1971), which did not contain nitrogen.…”

Section: Nodulation Assaymentioning

confidence: 99%

Characterization of MocR, a GntR-like transcriptional regulator, in Bradyrhizobium japonicum: its impact on motility, biofilm formation, and soybean nodulation

Taw

Lee

et al. 2015

J Microbiol.

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Bradyrhizobium japonicum is a Gram-negative soil bacterium that can fix nitrogen into ammonia by developing a symbiotic relationship with the soybean plant. MocR proteins make up a subfamily of GntR superfamily, one of the most widely distributed and prolific groups of the helix-turn-helix transcription factors. In this study, we constructed a mutant strain for mocR (blr6977) to investigate its role in cellular processes and symbiosis in B. japonicum. Although growth rate and morphology of the mutant were indistinguishable from those of the wild type, the mutant showed significant differences in motility and attachment (i.e., biofilm formation) from the wild type. The mutant displayed a decrease in biofilm formation, but was more motile than the wild type. The inactivation of mocR did not affect the number of nodules on soybean roots, but caused delayed nodulation. Delayed nodulation intrigued us to study competitiveness of the mutant infecting soybeans. The mutant was less competitive than the wild type, indicating that delayed nodulation might be due to competitiveness. Gene expressions of other MocR subfamily members were also compared between the wild type and mutant strains. None of the mocR-like genes examined in this study were differentially expressed between both strains.

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Effect of Soybean Coumestrol on Bradyrhizobium japonicum Nodulation Ability, Biofilm Formation, and Transcriptional Profile

Cited by 45 publications

References 57 publications

Polyphenolic Extract from Maple Syrup Potentiates Antibiotic Susceptibility and Reduces Biofilm Formation of Pathogenic Bacteria

Polyphenolic Extract from Maple Syrup Potentiates Antibiotic Susceptibility and Reduces Biofilm Formation of Pathogenic Bacteria

Effects of Indole-3-Acetic Acid on the Transcriptional Activities and Stress Tolerance of Bradyrhizobium japonicum

Characterization of MocR, a GntR-like transcriptional regulator, in Bradyrhizobium japonicum: its impact on motility, biofilm formation, and soybean nodulation

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