The HD-GYP Domain Protein RpfG of Xanthomonas oryzae pv. oryzicola Regulates Synthesis of Extracellular Polysaccharides that Contribute to Biofilm Formation and Virulence on Rice

Cyclic diguanylate monophosphate (c-di-GMP) is a secondary messenger present in bacteria. The GGDEF-domain proteins can participate in the synthesis of c-di-GMP as diguanylate cyclase (DGC) or bind with c-di-GMP to function as a c-di-GMP receptor. In the genome of Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of bacterial blight of rice, there are 11 genes that encode single GGDEF domain proteins. The GGDEF domain protein, PXO_02019 (here GdpX6 [GGDEF-domain protein of Xoo6]) was characterized in the present study. Firstly, the DGC and c-di-GMP binding activity of GdpX6 was confirmed in vitro. Mutation of the crucial residues D403 residue of the I site in GGDEF motif and E411 residue of A site in GGDEF motif of GdpX6 abolished c-di-GMP binding activity and DGC activity of GdpX6, respectively. Additionally, deletion of gdpX6 significantly increased the virulence, swimming motility, and decreased sliding motility and biofilm formation. In contrast, overexpression of GdpX6 in wild-type PXO99A strain decreased the virulence and swimming motility, and increased sliding motility and biofilm formation. Mutation of the E411 residue but not D403 residue of the GGDEF domain in GdpX6 abolished its biological functions, indicating the DGC activity to be imperative for its biological functions. Furthermore, GdpX6 exhibited multiple subcellular localization in bacterial cells, and D403 or E411 did not contribute to the localization of GdpX6. Thus, we concluded that GdpX6 exhibits DGC activity to control the virulence, swimming and sliding motility, and biofilm formation in Xoo.

Download Full-text

The Role of Exopolysaccharides in Oral Biofilms

Journal of Dental Research ◽

10.1177/0022034519845001 ◽

2019 ◽

Vol 98 (7) ◽

pp. 739-745 ◽

Cited By ~ 7

Author(s):

C. Cugini ◽

M. Shanmugam ◽

N. Landge ◽

N. Ramasubbu

Keyword(s):

Biofilm Formation ◽

Bacterial Colonization ◽

Super Resolution ◽

Extracellular Proteins ◽

Extracellular Polysaccharides ◽

Oral Biofilms ◽

The Matrix ◽

Oral Microbes ◽

Biofilm Development

The oral cavity contains a rich consortium of exopolysaccharide-producing microbes. These extracellular polysaccharides comprise a major component of the oral biofilm. Together with extracellular proteins, DNA, and lipids, they form the biofilm matrix, which contributes to bacterial colonization, biofilm formation and maintenance, and pathogenesis. While a number of oral microbes have been studied in detail with regard to biofilm formation and pathogenesis, the exopolysaccharides have been well characterized for only select organisms, namely Streptococcus mutans and Aggregatibacter actinomycetemcomitans. Studies on the exopolysaccharides of other oral organisms, however, are in their infancy. In this review, we present the current research on exopolysaccharides of oral microbes regarding their biosynthesis, regulation, contributions to biofilm formation and stability of the matrix, and immune evasion. In addition, insight into the role of exopolysaccharides in biofilms is highlighted through the evaluation of emerging techniques such as pH probing of biofilm colonies, solid-state nuclear magnetic resonance for macromolecular interactions within biofilms, and super-resolution microscopy analysis of biofilm development. Finally, exopolysaccharide as a potential nutrient source for species within a biofilm is discussed.

Download Full-text

Ursolic Acid Targets Glucosyltransferase and Inhibits Its Activity to Prevent Streptococcus mutans Biofilm Formation

Frontiers in Microbiology ◽

10.3389/fmicb.2021.743305 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yucui Liu ◽

Yanxin Huang ◽

Cong Fan ◽

Zhongmei Chi ◽

Miao Bai ◽

...

Keyword(s):

Streptococcus Mutans ◽

Ursolic Acid ◽

Biofilm Formation ◽

Natural Compound ◽

Structural Integrity ◽

Site Directed Mutagenesis ◽

Extracellular Polysaccharides ◽

Virulence Determinants ◽

Pentacyclic Triterpene ◽

Catalytic Center

Streptococcus mutans (S. mutans), the prime pathogen of dental caries, can secrete glucosyltransferases (GTFs) to synthesize extracellular polysaccharides (EPSs), which are the virulence determinants of cariogenic biofilms. Ursolic acid, a type of pentacyclic triterpene natural compound, has shown potential antibiofilm effects on S. mutans. To investigate the mechanisms of ursolic acid-mediated inhibition of S. mutans biofilm formation, we first demonstrated that ursolic acid could decrease the viability and structural integrity of biofilms, as evidenced by XTT, crystal violet, and live/dead staining assays. Then, we further revealed that ursolic acid could compete with the inherent substrate to occupy the catalytic center of GTFs to inhibit EPS formation, and this was confirmed by GTF activity assays, computer simulations, site-directed mutagenesis, and capillary electrophoresis (CE). In conclusion, ursolic acid can decrease bacterial viability and prevent S. mutans biofilm formation by binding and inhibiting the activity of GTFs.

Download Full-text

Discovery of Novel Dihydrolipoamide S-Succinyltransferase Inhibitors Based on Fragment Virtual Screening

International Journal of Molecular Sciences ◽

10.3390/ijms222312953 ◽

2021 ◽

Vol 22 (23) ◽

pp. 12953

Author(s):

Chengqian Wei ◽

Junjie Huang ◽

Yu Wang ◽

Yifang Chen ◽

Xin Luo ◽

...

Keyword(s):

Virtual Screening ◽

Antibacterial Agents ◽

High Efficiency ◽

Leaf Blight ◽

Xanthomonas Oryzae ◽

Bacterial Leaf Blight ◽

Extracellular Polysaccharides ◽

Bacterial Leaf Streak ◽

Bacterial Diseases ◽

Sulfone Derivatives

A series of new oxadiazole sulfone derivatives containing an amide moiety was synthesized based on fragment virtual screening to screen high-efficiency antibacterial agents for rice bacterial diseases. All target compounds showed greater bactericidal activity than commercial bactericides. 3-(4-fluorophenyl)-N-((5-(methylsulfonyl)-1,3,4-oxadiazol-2-yl)methyl)acrylamide (10) showed excellent antibacterial activity against Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola, with EC50 values of 0.36 and 0.53 mg/L, respectively, which were superior to thiodiazole copper (113.38 and 131.54 mg/L) and bismerthiazol (83.07 and 105.90 mg/L). The protective activity of compound 10 against rice bacterial leaf blight and rice bacterial leaf streak was 43.2% and 53.6%, respectively, which was superior to that of JHXJZ (34.1% and 26.4%) and thiodiazole copper (33.0% and 30.2%). The curative activity of compound 10 against rice bacterial leaf blight and rice bacterial leaf streak was 44.5% and 51.7%, respectively, which was superior to that of JHXJZ (32.6% and 24.4%) and thiodiazole copper (27.1% and 28.6%). Moreover, compound 10 might inhibit the growth of Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola by affecting the extracellular polysaccharides, destroying cell membranes, and inhibiting the enzyme activity of dihydrolipoamide S-succinyltransferase.

Download Full-text

Use of extracellular polysaccharides, secreted by Lactobacillus plantarum and Bacillus spp., as reducing indole production agents to control biofilm formation and efflux pumps inhibitor in Escherichia coli

Microbial Pathogenesis ◽

10.1016/j.micpath.2018.10.010 ◽

2018 ◽

Vol 125 ◽

pp. 448-453 ◽

Cited By ~ 6

Author(s):

Abdelkarim Mahdhi ◽

Nadia Leban ◽

Ibtissem Chakroun ◽

Sihem Bayar ◽

Kacem Mahdouani ◽

...

Keyword(s):

Escherichia Coli ◽

Lactobacillus Plantarum ◽

Biofilm Formation ◽

Efflux Pumps ◽

Extracellular Polysaccharides ◽

Bacillus Spp ◽

Indole Production

Download Full-text

PXO_RS20535, Encoding a Novel Response Regulator, Is Required for Chemotactic Motility, Biofilm Formation, and Tolerance to Oxidative Stress in Xanthomonas oryzae pv. oryzae

Pathogens ◽

10.3390/pathogens9110956 ◽

2020 ◽

Vol 9 (11) ◽

pp. 956

Author(s):

Abdulwahab Antar ◽

Mi-Ae Lee ◽

Youngchul Yoo ◽

Man-Ho Cho ◽

Sang-Won Lee

Keyword(s):

Oxidative Stress ◽

Mutant Strain ◽

Intracellular Signaling ◽

Biofilm Formation ◽

Response Regulator ◽

Xanthomonas Oryzae ◽

Knockout Mutant ◽

Gene Encoding ◽

Growth And Survival ◽

Intracellular Signaling Pathway

Xanthomonas oryzae pv. oryzae (Xoo), a causal agent of bacterial leaf blight of rice, possesses two-component regulatory systems (TCSs) as an intracellular signaling pathway. In this study, we observed changes in virulence, biofilm formation, motility, chemotaxis, and tolerance against oxidative stress of a knockout mutant strain for the PXO_RS20535 gene, encoding an orphan response regulator (RR). The mutant strain lost virulence, produced significantly less biofilm, and showed remarkably reduced motility in swimming, swarming, and twitching. Furthermore, the mutant strain lost glucose-guided movement and showed clear diminution of growth and survival in the presence of H2O2. These results indicate that the RR protein encoded in the PXO_RS20535 gene (or a TCS mediated by the protein) is closely involved in regulation of biofilm formation, all types of motility, chemotaxis, and tolerance against reactive oxygen species (ROS) in Xoo. Moreover we found that the expression of most genes required for a type six secretion system (T6SS) was decreased in the mutant, suggesting that lack of the RR gene most likely leads to defect of T6SS in Xoo.

Download Full-text

N-Acetyl-l-Cysteine Affects Growth, Extracellular Polysaccharide Production, and Bacterial Biofilm Formation on Solid Surfaces

Applied and Environmental Microbiology ◽

10.1128/aem.69.8.4814-4822.2003 ◽

2003 ◽

Vol 69 (8) ◽

pp. 4814-4822 ◽

Cited By ~ 133

Author(s):

Ann-Cathrin Olofsson ◽

Malte Hermansson ◽

Hans Elwing

Keyword(s):

Stainless Steel ◽

Bacterial Adhesion ◽

Biofilm Formation ◽

Paper Mill ◽

Bacterial Biofilm ◽

Extracellular Polysaccharides ◽

Positive Effects ◽

Initial Adhesion ◽

Interesting Candidate ◽

Steel Surfaces

ABSTRACT N-Acetyl-l-cysteine (NAC) is used in medical treatment of patients with chronic bronchitis. The positive effects of NAC treatment have primarily been attributed to the mucus-dissolving properties of NAC, as well as its ability to decrease biofilm formation, which reduces bacterial infections. Our results suggest that NAC also may be an interesting candidate for use as an agent to reduce and prevent biofilm formation on stainless steel surfaces in environments typical of paper mill plants. Using 10 different bacterial strains isolated from a paper mill, we found that the mode of action of NAC is chemical, as well as biological, in the case of bacterial adhesion to stainless steel surfaces. The initial adhesion of bacteria is dependent on the wettability of the substratum. NAC was shown to bind to stainless steel, increasing the wettability of the surface. Moreover, NAC decreased bacterial adhesion and even detached bacteria that were adhering to stainless steel surfaces. Growth of various bacteria, as monocultures or in a multispecies community, was inhibited at different concentrations of NAC. We also found that there was no detectable degradation of extracellular polysaccharides (EPS) by NAC, indicating that NAC reduced the production of EPS, in most bacteria tested, even at concentrations at which growth was not affected. Altogether, the presence of NAC changes the texture of the biofilm formed and makes NAC an interesting candidate for use as a general inhibitor of formation of bacterial biofilms on stainless steel surfaces.

Download Full-text

The Role of a Host-Induced Arginase of Xanthomonas oryzae pv. oryzae in Promoting Virulence on Rice

Phytopathology ◽

10.1094/phyto-02-19-0058-r ◽

2019 ◽

Vol 109 (11) ◽

pp. 1869-1877

Author(s):

Yuqiang Zhang ◽

Guichun Wu ◽

Ian Palmer ◽

Bo Wang ◽

Guoliang Qian ◽

...

Keyword(s):

Biofilm Formation ◽

Bacterial Blight ◽

Wild Type Strain ◽

Bacterial Pathogen ◽

Extracellular Polysaccharide ◽

Rice Cultivar ◽

Xanthomonas Oryzae ◽

Wild Type ◽

Bacterial Blight Of Rice

The plant bacterial pathogen Xanthomonas oryzae pv. oryzae causes bacterial blight of rice, which is one of the most destructive rice diseases prevalent in Asia and parts of Africa. Despite many years of research, how X. oryzae pv. oryzae causes bacterial blight of rice is still not completely understood. Here, we show that the loss of the rocF gene caused a significant decrease in the virulence of X. oryzae pv. oryzae in the susceptible rice cultivar IR24. Bioinformatics analysis demonstrated that rocF encodes arginase. Quantitative real-time PCR and Western blot assays revealed that rocF expression was significantly induced by rice and arginine. The rocF deletion mutant strain showed elevated sensitivity to hydrogen peroxide, reduced extracellular polysaccharide (EPS) production, and reduced biofilm formation, all of which are important determinants for the full virulence of X. oryzae pv. oryzae, compared with the wild-type strain. Taken together, the results of this study revealed a mechanism by which a bacterial arginase is required for the full virulence of X. oryzae pv. oryzae on rice because of its contribution to tolerance to reactive oxygen species, EPS production, and biofilm formation.

Download Full-text

PXO_00987, a putative acetyltransferase, is required for flagellin glycosylation, and regulates flagellar motility, exopolysaccharide production, and biofilm formation in Xanthomonas oryzae pv. oryzae

Microbial Pathogenesis ◽

10.1016/j.micpath.2015.06.001 ◽

2015 ◽

Vol 85 ◽

pp. 50-57 ◽

Cited By ~ 8

Author(s):

Haiyun Li ◽

Chao Yu ◽

Huamin Chen ◽

Fang Tian ◽

Chenyang He

Keyword(s):

Biofilm Formation ◽

Xanthomonas Oryzae ◽

Flagellar Motility ◽

Exopolysaccharide Production ◽

Flagellin Glycosylation

Download Full-text

A Sustained-Release Membrane of Thiazolidinedione-8: Effect on Formation of a Candida/Bacteria Mixed Biofilm on Hydroxyapatite in a Continuous Flow Model

BioMed Research International ◽

10.1155/2017/3510124 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 9

Author(s):

Mark Feldman ◽

Julia Shenderovich ◽

Eran Lavy ◽

Michael Friedman ◽

Doron Steinberg

Keyword(s):

Sustained Release ◽

Biofilm Formation ◽

Active Agent ◽

Extracellular Polysaccharides ◽

Flow Conditions ◽

Biofilm Thickness ◽

Release Drug ◽

Flow Through ◽

Biofilm Development ◽

The Impact

Thiazolidinediones (TZDs) have been found to act as effective quorum sensing quenchers, capable of preventing biofilm formation. Our previous studies demonstrated a profound antibiofilm effect of the TZD derivative thiazolidinedione-8 (S-8), either in solution or incorporated into a sustained-release membrane (SRM-S-8) under batch conditions. In the present study, we used a constant depth film fermenter model in order to investigate the impact of SRM-S-8 on mixedC. albicans-S. mutansbiofilm development, under flow conditions. We found that essential parameters of cospecies biofilm maintenance and maturation, such as metabolic activity, biofilm thickness, roughness, extracellular polysaccharides production, and morphology of both pathogens, were altered by SRM-S-8 in the flow system. We propose that prolonged and sustained release of S-8 in a flow-through system allows better penetration of the active agent to deeper layers of the mixed biofilm, thereby increasing its activity against both pathogens. In conclusion, the use of a locally applied sustained-release drug delivery system of S-8 can affect the dental polymicrobial biofilm, resulting in clinical improvements and a better patient compliance.

Download Full-text