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902400.9878Tackling Virulence of Pseudomonas aeruginosa by the Natural Furanone Sotolon. The bacterial resistance development due to the incessant administration of antibiotics has led to difficulty in their treatment. Natural adjuvant compounds can be co-administered to hinder the pathogenesis of resistant bacteria. Sotolon is the prevailing aromatic compound that gives fenugreek its typical smell. In the current work, the anti-virulence activities of sotolon on Pseudomonas aeruginosa have been evaluated. P. aeruginosa has been treated with sotolon at sub-minimum inhibitory concentration (MIC), and production of biofilm and other virulence factors were assessed. Moreover, the anti-quorum sensing (QS) activity of sotolon was in-silico evaluated by evaluating the affinity of sotolon to bind to QS receptors, and the expression of QS genes was measured in the presence of sotolon sub-MIC. Furthermore, the sotolon in-vivo capability to protect mice against P. aeruginosa was assessed. Significantly, sotolon decreased the production of bacterial biofilm and virulence factors, the expression of QS genes, and protected mice from P. aeruginosa. Conclusively, the plant natural substance sotolon attenuated the pathogenicity of P. aeruginosa, locating it as a plausible potential therapeutic agent for the treatment of its infections. Sotolon can be used in the treatment of bacterial infections as an alternative or adjuvant to antibiotics to combat their high resistance to antibiotics.202134356792
1810.9864Antivirulence effects of cell-free culture supernatant of endophytic bacteria against grapevine crown gall agent, Agrobacterium tumefaciens, and induction of defense responses in plantlets via intact bacterial cells. BACKGROUND: Crown gall disease caused by Agrobacterium tumefaciens is a very destructive affliction that affects grapevines. Endophytic bacteria have been discovered to control plant diseases via the use of several mechanisms. This research examined the potential for controlling crown gall by three endophytic bacteria that were previously isolated from healthy cultivated and wild grapevines including Pseudomonas kilonensis Ba35, Pseudomonas chlororaphis Ba47, and Serratia liquefaciens Ou55. RESULT: At various degrees, three endophytic bacteria suppressed the populations of A. tumefaciens Gh1 and greatly decreased the symptoms of crown gall. Furthermore, biofilm production and motility behaviors of A. tumefaciens Gh1were greatly inhibited by the Cell-free Culture Supernatant (CFCS) of endophytic bacteria. According to our findings, CFCS may reduce the adhesion of A. tumefaciens Gh1 cells to grapevine cv. Rashe root tissues as well as their chemotaxis motility toward the extract of the roots. When compared to the untreated control, statistical analysis showed that CFCS significantly reduced the swimming, twitching, and swarming motility of A. tumefaciens Gh1. The findings demonstrated that the endophytic bacteria effectively stimulated the production of plant defensive enzymes including superoxide dismutase (SOD), polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia lyase (PAL), and total soluble phenols at different time intervals in grapevine inoculated with A. tumefaciens Gh1. The Ba47 strain markedly increased the expression levels of defense genes associated with plant resistance. The up-regulation of PR1, PR2, VvACO1, and GAD1 genes in grapevine leaves indicates the activation of SA and JA pathways, which play a role in enhancing resistance to pathogen invasion. The results showed that treating grapevine with Ba47 increased antioxidant defense activities and defense-related gene expression, which reduced oxidative damage caused by A. tumefaciens and decreased the incidence of crown gall disease. CONCLUSION: This is the first study on how A. tumefaciens, the grapevine crown gall agent, is affected by CFCS generated by endophytic bacteria in terms of growth and virulence features. To create safer plant disease management techniques, knowledge of the biocontrol processes mediated by CFCS during microbial interactions is crucial.202438336608
879020.9861Bacillus circulans GN03 Alters the Microbiota, Promotes Cotton Seedling Growth and Disease Resistance, and Increases the Expression of Phytohormone Synthesis and Disease Resistance-Related Genes. Plant growth-promoting bacteria (PGPB) are components of the plant rhizosphere that promote plant growth and/or inhibit pathogen activity. To explore the cotton seedlings response to Bacillus circulans GN03 with high efficiency of plant growth promotion and disease resistance, a pot experiment was carried out, in which inoculations levels of GN03 were set at 10(4) and 10(8) cfu(⋅)mL(-1). The results showed that GN03 inoculation remarkably enhanced growth promotion as well as disease resistance of cotton seedlings. GN03 inoculation altered the microbiota in and around the plant roots, led to a significant accumulation of growth-related hormones (indole acetic acid, gibberellic acid, and brassinosteroid) and disease resistance-related hormones (salicylic acid and jasmonic acid) in cotton seedlings, as determined with ELISA, up-regulated the expression of phytohormone synthesis-related genes (EDS1, AOC1, BES1, and GA20ox), auxin transporter gene (Aux1), and disease-resistance genes (NPR1 and PR1). Comparative genomic analyses was performed between GN03 and four similar species, with regards to phenotype, biochemical characteristics, and gene function. This study provides valuable information for applying the PGPB alternative, GN03, as a plant growth and disease-resistance promoting fertilizer.202133936131
636930.9859Association of furanone C-30 with biofilm formation & antibiotic resistance in Pseudomonas aeruginosa. BACKGROUND & OBJECTIVES: Pseudomonas aeruginosa is an opportunistic pathogen that can cause nosocomial bloodstream infections in humans. This study was aimed to explore the association of furanone C-30 with biofilm formation, quorum sensing (QS) system and antibiotic resistance in P. aeruginosa. METHODS: An in vitro model of P. aeruginosa bacterial biofilm was established using the standard P. aeruginosa strain (PAO-1). After treatment with 2.5 and 5 μg/ml of furanone C-30, the change of biofilm morphology of PAO-1 was observed, and the expression levels of QS-regulated virulence genes (lasB, rhlA and phzA2), QS receptor genes (lasR, rhlR and pqsR) as well as QS signal molecule synthase genes (lasI, rhlI, pqsE and pqsH) were determined. Besides, the AmpC expression was quantified in planktonic and mature biofilm induced by antibiotics. RESULTS: Furanone C-30 treatment significantly inhibited biofilm formation in a dose-dependent manner. With the increase of furanone C-30 concentration, the expression levels of lasB, rhlA, phzA2, pqsR, lasI, rhlI pqsE and pqsH significantly decreased in mature biofilm bacteria while the expression levels of lasR and rhlR markedly increased. The AmpC expression was significantly decreased in both planktonic and biofilm bacteria induced by imipenem and ceftazidime. INTERPRETATION & CONCLUSIONS: Furanone C-30 may inhibit biofilm formation and antibiotic resistance in P. aeruginosa through regulating QS genes. The inhibitory effect of furanone C-30 on las system appeared to be stronger than that on rhl system. Further studies need to be done with different strains of P. aeruginosa to confirm our findings.201829998876
1740.9859Biocontrol Potential of Endophytic Plant-Growth-Promoting Bacteria against Phytopathogenic Viruses: Molecular Interaction with the Host Plant and Comparison with Chitosan. Endophytic plant-growth-promoting bacteria (ePGPB) are interesting tools for pest management strategies. However, the molecular interactions underlying specific biocontrol effects, particularly against phytopathogenic viruses, remain unexplored. Herein, we investigated the antiviral effects and triggers of induced systemic resistance mediated by four ePGPB (Paraburkholderia fungorum strain R8, Paenibacillus pasadenensis strain R16, Pantoea agglomerans strain 255-7, and Pseudomonas syringae strain 260-02) against four viruses (Cymbidium Ring Spot Virus-CymRSV; Cucumber Mosaic Virus-CMV; Potato Virus X-PVX; and Potato Virus Y-PVY) on Nicotiana benthamiana plants under controlled conditions and compared them with a chitosan-based resistance inducer product. Our studies indicated that ePGPB- and chitosan-treated plants presented well-defined biocontrol efficacy against CymRSV and CMV, unlike PVX and PVY. They exhibited significant reductions in symptom severity while promoting plant height compared to nontreated, virus-infected controls. However, these phenotypic traits showed no association with relative virus quantification. Moreover, the tested defense-related genes (Enhanced Disease Susceptibility-1 (EDS1), Non-expressor of Pathogenesis-related genes-1 (NPR1), and Pathogenesis-related protein-2B (PR2B)) implied the involvement of a salicylic-acid-related defense pathway triggered by EDS1 gene upregulation.202235805989
476850.9858Attenuating the virulence of the resistant superbug Staphylococcus aureus bacteria isolated from neonatal sepsis by ascorbic acid, dexamethasone, and sodium bicarbonate. BACKGROUND: Infections affecting neonates caused by Staphylococcus aureus are widespread in healthcare facilities; hence, novel strategies are needed to fight this pathogen. In this study, we aimed to investigate the effectiveness of the FDA-approved medications ascorbic acid, dexamethasone, and sodium bicarbonate to reduce the virulence of the resistant Staphylococcus aureus bacteria that causes neonatal sepsis and seek out suitable alternatives to the problem of multi-drug resistance. METHODS: Tested drugs were assessed phenotypically and genotypically for their effects on virulence factors and virulence-encoding genes in Staphylococcus aureus. Furthermore, drugs were tested in vivo for their ability to reduce Staphylococcus aureus pathogenesis. RESULTS: Sub-inhibitory concentrations (1/8 MIC) of ascorbic acid, dexamethasone, and sodium bicarbonate reduced the production of Staphylococcus aureus virulence factors, including biofilm formation, staphyloxanthin, proteases, and hemolysin production, as well as resistance to oxidative stress. At the molecular level, qRT-PCR was used to assess the relative expression levels of crtM, sigB, sarA, agrA, hla, fnbA, and icaA genes regulating virulence factors production and showed a significant reduction in the relative expression levels of all the tested genes. CONCLUSIONS: The current findings reveal that ascorbic acid, dexamethasone, and sodium bicarbonate have strong anti-virulence effects against Staphylococcus aureus. Thus, suggesting that they might be used as adjuvants to treat infections caused by Staphylococcus aureus in combination with conventional antimicrobials or as alternative therapies.202236348266
876860.9858Selective regulation of endophytic bacteria and gene expression in soybean by water-soluble humic materials. BACKGROUND: As part of the plant microbiome, endophytic bacteria play an essential role in plant growth and resistance to stress. Water-soluble humic materials (WSHM) is widely used in sustainable agriculture as a natural and non-polluting plant growth regulator to promote the growth of plants and beneficial bacteria. However, the mechanisms of WSHM to promote plant growth and the evidence for commensal endophytic bacteria interaction with their host remain largely unknown. Here, 16S rRNA gene sequencing, transcriptomic analysis, and culture-based methods were used to reveal the underlying mechanisms. RESULTS: WSHM reduced the alpha diversity of soybean endophytic bacteria, but increased the bacterial interactions and further selectively enriched the potentially beneficial bacteria. Meanwhile, WSHM regulated the expression of various genes related to the MAPK signaling pathway, plant-pathogen interaction, hormone signal transduction, and synthetic pathways in soybean root. Omics integration analysis showed that Sphingobium was the genus closest to the significantly changed genes in WSHM treatment. The inoculation of endophytic Sphingobium sp. TBBS4 isolated from soybean significantly improved soybean nodulation and growth by increasing della gene expression and reducing ethylene release. CONCLUSION: All the results revealed that WSHM promotes soybean nodulation and growth by selectively regulating soybean gene expression and regulating the endophytic bacterial community, Sphingobium was the key bacterium involved in plant-microbe interaction. These findings refined our understanding of the mechanism of WSHM promoting soybean nodulation and growth and provided novel evidence for plant-endophyte interaction.202438178261
873370.9857Enhanced anti-herbivore defense of tomato plants against Spodoptera litura by their rhizosphere bacteria. BACKGROUND: The use of beneficial microorganisms as an alternative for pest control has gained increasing attention. The objective of this study was to screen beneficial rhizosphere bacteria with the ability to enhance tomato anti-herbivore resistance. RESULTS: Rhizosphere bacteria in tomato field from Fuqing, one of the four locations where rhizosphere bacteria were collected in Fujian, China, enhanced tomato resistance against the tobacco cutworm Spodoptera litura, an important polyphagous pest. Inoculation with the isolate T6-4 obtained from the rhizosphere of tomato field in Fuqing reduced leaf damage and weight gain of S. litura larvae fed on the leaves of inoculated tomato plants by 27% in relative to control. Analysis of 16S rRNA gene sequence identities indicated that the isolate T6-4 was closely related to Stenotrophomonas rhizophila supported with 99.37% sequence similarity. In the presence of S. litura infestation, inoculation with the bacterium led to increases by a 66.9% increase in protease inhibitor activity, 53% in peroxidase activity and 80% in polyphenol oxidase activity in the leaves of inoculated plants as compared to the un-inoculated control. Moreover, the expression levels of defense-related genes encoding allene oxide cyclase (AOC), allene oxide synthase (AOS), lipoxygenase D (LOXD) and proteinase inhibitor (PI-II) in tomato leaves were induced 2.2-, 1.7-, 1.4- and 2.7-fold, respectively by T6-4 inoculation. CONCLUSION: These results showed that the tomato rhizosphere soils harbor beneficial bacteria that can systemically induce jasmonate-dependent anti-herbivore resistance in tomato plants.202235606741
602980.9856Characterization of Potential Virulence, Resistance to Antibiotics and Heavy Metals, and Biofilm-Forming Capabilities of Soil Lignocellulolytic Bacteria. Soil bacteria participate in self-immobilization processes for survival, persistence, and production of virulence factors in some niches or hosts through their capacities for autoaggregation, cell surface hydrophobicity, biofilm formation, and antibiotic and heavy metal resistance. This study investigated potential virulence, antibiotic and heavy metal resistance, solvent adhesion, and biofilm-forming capabilities of six cellulolytic bacteria isolated from soil samples: Paenarthrobacter sp. MKAL1, Hymenobacter sp. MKAL2, Mycobacterium sp. MKAL3, Stenotrophomonas sp. MKAL4, Chryseobacterium sp. MKAL5, and Bacillus sp. MKAL6. Strains were subjected to phenotypic methods, including heavy metal and antibiotic susceptibility and virulence factors (protease, lipase, capsule production, autoaggregation, hydrophobicity, and biofilm formation). The effect of ciprofloxacin was also investigated on bacterial susceptibility over time, cell membrane, and biofilm formation. Strains MKAL2, MKAL5, and MKAL6 exhibited protease and lipase activities, while only MKAL6 produced capsules. All strains were capable of aggregating, forming biofilm, and adhering to solvents. Strains tolerated high amounts of chromium, lead, zinc, nickel, and manganese and were resistant to lincomycin. Ciprofloxacin exhibited bactericidal activity against these strains. Although the phenotypic evaluation of virulence factors of bacteria can indicate their pathogenic nature, an in-depth genetic study of virulence, antibiotic and heavy metal resistance genes is required.202336944321
878790.9856Improved resistance against Botrytis cinerea by grapevine-associated bacteria that induce a prime oxidative burst and phytoalexin production. Bacteria such as Pantoea agglomerans (Pa-AF2), Bacillus subtilis (Bs-271), Acinetobacter lwoffii (Al-113), and Pseudomonas fluorescens (Pf-CT2), originating from the vineyard, can induce defense responses and enhance resistance of grapevine against the fungal pathogen Botrytis cinerea. The perception of these bacteria by plant cells or tissues in relation to their activities remains unknown. In this study, we examined the relationships between the activity of each bacterium to induce or prime some defense responses, and its effectiveness to induce resistance in grapevine against B. cinerea. We showed that all selected bacteria are capable of inducing early oxidative burst and phytoalexin (trans-resveratrol and trans-ε-viniferin) production in grapevine cells and leaves. Pf-CT2 and Al-113 induced higher H(2)O(2) and trans-resveratrol accumulations, and were able to further prime plants for accelerated phytoalexin production after B. cinerea challenge. These two bacteria were also the most effective in inducing local and systemic resistance. A similar level of induced resistance was observed with live Pa-AF2 which also induced but not primed a greater accumulation of trans-resveratrol. However, Bs-271, which was less effective in inducing resistance, induced a lower trans-resveratrol synthesis, without priming activity. Treatment of grapevine cells with growing medium or crude extract of the bacteria quickly and strongly enhanced oxidative burst compared with the live bacteria. However, both treatments resulted in comparable amounts of phytoalexins and induced local and systemic resistance to B. cinerea as compared with those induced by living bacteria, with extracts from Pf-CT2 and Al-113 being the most effective. Together, these results indicate that induced resistance can be improved by treatment with bacteria or derived compounds which induced or primed plants for enhanced phytoalexin accumulation.201121425931
6159100.9855Gene expression profiling of Cecropin B-resistant Haemophilus parasuis. Synthetically designed antimicrobial peptides (AMPs) present the potential of replacing antibiotics in the treatment of bacterial infections. However, microbial resistance to AMPs has been reported and little is known regarding the underlying mechanism of such resistance. The naturally occurring AMP cecropin B (CB) disrupts the anionic cell membranes of Gram-negative bacteria. In this study, CB resistance (CBR) was induced in Haemophilusparasuis SH0165 by exposing it to a series of CB concentrations. The CB-resistant H.parasuis strains CBR30 and CBR30-50 were obtained. The growth curves of SH0165 and CBR30 showed that CBR30 displayed lower growth rates than SH0165. The result of transmission electron microscopy showed cell membranes of the CB-resistant CBR30 and CBR30-50 were smoother than SH0165. Microarrays detected 257 upregulated and 254 downregulated genes covering 20 clusters of orthologous groups (COGs) of the CB-resistant CBR30 compared with SH0165 (>1.5-fold change, p < 0.05). Sixty genes were affected in CBR30-50 covering 18 COGs, with 28 upregulated and 32 downregulated genes. Under the COG function classification, the majority of affected genes in the CB-resistant CBR30 and CBR30-50 belong to the category of inorganic ion transport, amino acid transport, and metabolism. The microarray results were validated by real-time quantitative reverse transcription PCR. This study may provide useful guidance for understanding the molecular mechanism underlying H.parasuis resistance to CB.201424862339
9022110.9855Drug repositioning: doxazosin attenuates the virulence factors and biofilm formation in Gram-negative bacteria. The resistance development is an increasing global health risk that needs innovative solutions. Repurposing drugs to serve as anti-virulence agents is suggested as an advantageous strategy to diminish bacterial resistance development. Bacterial virulence is controlled by quorum sensing (QS) system that orchestrates the expression of biofilm formation, motility, and virulence factors production as enzymes and virulent pigments. Interfering with QS could lead to bacterial virulence mitigation without affecting bacterial growth that does not result in bacterial resistance development. This study investigated the probable anti-virulence and anti-QS activities of α-adrenoreceptor blocker doxazosin against Proteus mirabilis and Pseudomonas aeruginosa. Besides in silico study, in vitro and in vivo investigations were conducted to assess the doxazosin anti-virulence actions. Doxazosin significantly diminished the biofilm formation and release of QS-controlled Chromobacterium violaceum pigment and virulence factors in P. aeruginosa and P. mirabilis, and downregulated the QS encoding genes in P. aeruginosa. Virtually, doxazosin interfered with QS proteins, and in vivo protected mice against P. mirabilis and P. aeruginosa. The role of the membranal sensors as QseC and PmrA was recognized in enhancing the Gram-negative virulence. Doxazosin downregulated the membranal sensors PmR and QseC encoding genes and could in silico interfere with them. In conclusion, this study preliminary documents the probable anti-QS and anti-virulence activities of doxazosin, which indicate its possible application as an alternative or in addition to antibiotics. However, extended toxicological and pharmacological investigations are essential to approve the feasible clinical application of doxazosin as novel efficient anti-virulence agent. KEY POINTS: • Anti-hypertensive doxazosin acquires anti-quorum sensing activities • Doxazosin diminishes the virulence of Proteus mirabilis and Pseudomonas aeruginosa • Doxazosin could dimmish the bacterial espionage.202337079062
8889120.9855Differences in Gene Expression Profiles between Early and Late Isolates in Monospecies Achromobacter Biofilm. Bacteria of genus Achromobacter are emerging pathogens in cystic fibrosis (CF) capable of biofilm formation and development of antimicrobial resistance. Evolutionary adaptions in the transition from primary to chronic infection were assessed by transcriptomic analysis of successive isolates of Achromobacter xylosoxidans from a single CF patient. Several efflux pump systems targeting antimicrobial agents were upregulated during the course of the disease, whereas all genes related to motility were downregulated. Genes annotated to subsystems of sulfur metabolism, protein metabolism and potassium metabolism exhibited the strongest upregulation. K+ channel genes were hyperexpressed, and a putative sulfite oxidase was more than 1500 times upregulated. The transcriptome patterns indicated a pivotal role of sulfur metabolism and electrical signalling in Achromobacter biofilms during late stage CF lung disease.201728534862
8797130.9855Presence of quorum-sensing systems associated with multidrug resistance and biofilm formation in Bacteroides fragilis. Bacteroides fragilis constitutes 1-2% of the natural microbiota of the human digestive tract and is the predominant anaerobic opportunistic pathogen in gastrointestinal infections. Most bacteria use quorum sensing (QS) to monitor cell density in relation to other cells and their environment. In Gram-negative bacteria, the LuxRI system is common. The luxR gene encodes a transcriptional activator inducible by type I acyl-homoserine lactone autoinducers (e.g., N-[3-oxohexanoyl] homoserine lactone and hexanoyl homoserine lactone [C6-HSL]). This study investigated the presence of QS system(s) in B. fragilis. The genome of American-type culture collection strain no. ATCC25285 was searched for QS genes. The strain was grown to late exponential phase in the presence or absence of synthetic C6-HSL and C8-HSL or natural homoserine lactones from cell-free supernatants from spent growth cultures of other bacteria. Growth, susceptibility to antimicrobial agents, efflux pump gene (bmeB) expression, and biofilm formation were measured. Nine luxR and no luxI orthologues were found. C6-HSL and supernatants from Yersinia enterocolitica, Vibrio cholerae, and Pseudomonas aeruginosa caused a significant (1) reduction in cellular density and (2) increases in expression of four putative luxR genes, bmeB3, bmeB6, bmeB7, and bmeB10, resistance to various antibiotics, which was reduced by carbonyl cyanide-m-chlorophenyl hydrazone (CCCP, an uncoupler that dissipates the transmembrane proton gradient, which is also the driving force of resistance nodulation division efflux pumps) and (3) increase in biofilm formation. Susceptibility of ATCC25285 to C6-HSL was also reduced by CCCP. These data suggest that (1) B. fragilis contains putative luxR orthologues, which could respond to exogenous homoserine lactones and modulate biofilm formation, bmeB efflux pump expression, and susceptibility to antibiotics, and (2) BmeB efflux pumps could transport homoserine lactones.200818188535
8765140.9855Pseudomonas chlororaphis IRHB3 assemblies beneficial microbes and activates JA-mediated resistance to promote nutrient utilization and inhibit pathogen attack. INTRODUCTION: The rhizosphere microbiome is critical to plant health and resistance. PGPR are well known as plant-beneficial bacteria and generally regulate nutrient utilization as well as plant responses to environmental stimuli. In our previous work, one typical PGPR strain, Pseudomonas chlororaphis IRHB3, isolated from the soybean rhizosphere, had positive impacts on soil-borne disease suppression and growth promotion in the greenhouse, but its biocontrol mechanism and application in the field are not unclear. METHODS: In the current study, IRHB3 was introduced into field soil, and its effects on the local rhizosphere microbiome, disease resistance, and soybean growth were comprehensively analyzed through high-throughput sequencing and physiological and molecular methods. RESULTS AND DISCUSSION: We found that IRHB3 significantly increased the richness of the bacterial community but not the structure of the soybean rhizosphere. Functional bacteria related to phosphorus solubilization and nitrogen fixation, such as Geobacter, Geomonas, Candidatus Solibacter, Occallatibacter, and Candidatus Koribacter, were recruited in rich abundance by IRHB3 to the soybean rhizosphere as compared to those without IRHB3. In addition, the IRHB3 supplement obviously maintained the homeostasis of the rhizosphere microbiome that was disturbed by F. oxysporum, resulting in a lower disease index of root rot when compared with F. oxysporum. Furthermore, JA-mediated induced resistance was rapidly activated by IRHB3 following PDF1.2 and LOX2 expression, and meanwhile, a set of nodulation genes, GmENOD40b, GmNIN-2b, and GmRIC1, were also considerably induced by IRHB3 to improve nitrogen fixation ability and promote soybean yield, even when plants were infected by F. oxysporum. Thus, IRHB3 tends to synergistically interact with local rhizosphere microbes to promote host growth and induce host resistance in the field.202438380096
9044150.9854Impairment of novel non-coding small RNA00203 inhibits biofilm formation and reduces biofilm-specific antibiotic resistance in Acinetobacter baumannii. Small RNAs (sRNAs) are post-transcriptional regulators of many biological processes in bacteria, including biofilm formation and antibiotic resistance. The mechanisms by which sRNA regulates the biofilm-specific antibiotic resistance in Acinetobacter baumannii have not been reported to date. This study aimed to investigate the influence of sRNA00203 (53 nucleotides) on biofilm formation, antibiotic susceptibility, and expression of genes associated with biofilm formation and antibiotic resistance. The results showed that deletion of the sRNA00203-encoding gene decreased the biomass of biofilm by 85%. Deletion of the sRNA00203-encoding gene also reduced the minimum biofilm inhibitory concentrations for imipenem and ciprofloxacin 1024- and 128-fold, respectively. Knocking out of sRNA00203 significantly downregulated genes involved in biofilm matrix synthesis (pgaB), efflux pump production (novel00738), lipopolysaccharide biosynthesis (novel00626), preprotein translocase subunit (secA) and the CRP transcriptional regulator. Overall, the suppression of sRNA00203 in an A. baumannii ST1894 strain impaired biofilm formation and sensitized the biofilm cells to imipenem and ciprofloxacin. As sRNA00203 was found to be conserved in A. baumannii, a therapeutic strategy targeting sRNA00203 may be a potential solution for the treatment of biofilm-associated infections caused by A. baumannii. To the best of the authors' knowledge, this is the first study to show the impact of sRNA00203 on biofilm formation and biofilm-specific antibiotic resistance in A. baumannii.202337315907
8783160.9853Characterization and potential of plant growth promoting rhizobacteria isolated from native Andean crops. Bacteria isolated from soil and rhizosphere samples collected in Peru from Andean crops were tested in vitro and in vivo to determine their potential as plant growth promoters and their ability to induce systemic resistance to Alternaria alternata in tomato plants. The isolates were identified by sequencing their 16S ribosomal RNA gene. Test for phosphate solubilization, and indolacetic acid were also carried out, together with in vitro antagonism assays in dual cultures towards the plant pathogens Fusarium solani, A. alternata and Curvularia lunata. The three most promising isolates (Pa15, Ps155, Ps168) belonged to the genus Pseudomonas. Further assays were carried out with tomato plants to assess their plant protection effect towards A. alternata and as growth promoters. Inoculation of tomato seeds with all isolates significantly enhanced seed germination, plantlets emergence and plant development. Bacterial inoculation also reduce damage level caused by A. alternata. The expression levels of three tomato genes involved in the jasmonate (AOS), ethylene responsive (ERF-2) and pathogenesis related (PR-P2) pathways were determined in plants challenged with A. alternata, alone or with each bacterial isolate, respectively. Results showed that at 24 h after infection, in absence of the pathogen, the expression level of the tested genes was very low. The presence of A. alternata alone and in combination with bacteria increased the transcripts of all genes. Data showed a potential of best performing isolate Ps168 to sustain tomato plants nutrition and activate defense-related genes for protection by pathogenic fungi.201729079927
6079170.9853Genomic and metabonomic methods reveal the probiotic functions of swine-derived Ligilactobacillus salivarius. BACKGROUND: As substitutes for antibiotics, probiotic bacteria protect against digestive infections caused by pathogenic bacteria. Ligilactobacillus salivarius is a species of native lactobacillus found in both humans and animals. Herein, a swine-derived Ligilactobacillus salivarius was isolated and shown to colonize the ileal mucous membrane, thereby promoting nutritional digestion, absorption, and immunity. To evaluate its probiotic role, the entire genome was sequenced, the genetic information was annotated, and the metabolic information was analyzed. RESULTS: The phylogenetic relationship indicated that the bacteria was closer to L. salivarius MT573555.1 and MT585431.1. Functional genes included transporters, membrane proteins, enzymes, heavy metal resistance proteins, and putative proteins; metabolism-related genes were the most abundant. The six types of metabolic pathways secreted by L. salivarius were mainly composed of secretory transmembrane proteins and peptides. The secretory proteins of L. salivarius were digestive enzymes, functional proteins that regulate apoptosis, antibodies, and hormones. Non-targeted metabolomic analysis of L. salivarius metabolites suggested that ceramide, pyrrolidone- 5- carboxylic acid, N2-acetyl-L-ornithine, 2-ethyl-2-hydroxybutyric acid, N-lactoyl-phenylalanine, and 12 others were involved in antioxidation, repair of the cellular membrane, anticonvulsant, hypnosis, and appetite inhibition. Metabolites of clavaminic acid, antibiotic X14889C, and five other types of bacteriocins were identified, namely phenyllactic acid, janthitrem G, 13-demethyl tacrolimus, medinoside E, and tertonasin. The adherence and antioxidation of L. salivarius were also predicted. No virulence genes were found. CONCLUSION: The main probiotic properties of L. salivarius were identified using genomic, metabonomic, and biochemical assays, which are beneficial for porcine feeding. Our results provided deeper insights into the probiotic effects of L. salivarius.202337648978
8781180.9852Rhizosphere bacteria induce programmed cell death defence genes and signalling in chilli pepper. AIM: To understand how beneficial bacteria assist chilli plants (Capsicum annuum) in defence against biotrophic or hemibiotrophic pathogens. METHOD AND RESULTS: We quantified marker genes of plant defence pathways in Phytophthora capsici-infected chilli pepper treated with anti-oomycete plant growth-promoting rhizobacteria, Bacillus amyloliquefaciens, Bacillus velezensis and Acinetobacter sp. Plants displayed strong resistance, and the pathogen load in the roots was significantly lower in infected plants treated with bacterial biocontrol agents at all time points tested (1, 2 and 7 days after pathogen inoculation, p < 0.05). Gene expression profiling revealed that P. capsici infection in the absence of beneficial bacteria led to the upregulation of a wide array of defence genes. The addition of biocontrol bacteria modulated defence by further enhancing genes involved in programmed cell death, such as CaLOX1, CaPAL1, CaChitIV and CaPTI1, while suppressing others CaLRR1, a negative regulator of cell death. CONCLUSIONS: Our results suggest that the bacteria exerted a combined effect by directly antagonizing the pathogen and enhancing the expression of key plant defence genes, including those involved in cell death, causing resistance at early stages of infection by this hemibiotrophic pathogen.202235061923
8737190.9852Role of Biosynthetic Gene Cluster BGC3 in the Cariogenic Virulence of Streptococcus mutans. OBJECTIVE: To investigate the role of the biosynthetic gene cluster BGC3 of Streptococcus mutans (S. mutans) in the process of dental caries. METHODS: BGC3 and ∆BGC3 S. mutans strains were constructed and their growth curves were evaluated. Acid production capacity was assessed by evaluating pH reduction levels over identical culture periods. The survival of bacteria in phosphate citrate buffer solution (pH 3.0) was quantified. The expression levels of virulence genes (atpF, gtfC, gtfD, spaP, vicR and ftf) were analysed using the qPCR. Co-culture experiments were conducted to evaluate bacterial adaptability. Bacterial viability was determined by microscopical examination of live/dead staining. RESULTS: Deletion of BGC3 did not significantly impact S. mutans growth or acid production in biofilms. The ∆BGC3 strain exhibited enhanced acid resistance and higher expression levels of virulence genes compared to the wild type. In addition, ∆BGC3 exhibited superior bacterial viability in the co-culture system. CONCLUSION: BGC3 affected the acid resistance and expression of caries-related genes in S. mutans. The BGC3 knockout strain exhibited a more robust survival capability than the wild-type strain.202540162656