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902700.9340Scorpion Venom Antimicrobial Peptides Induce Siderophore Biosynthesis and Oxidative Stress Responses in Escherichia coli. The increasing development of microbial resistance to classical antimicrobial agents has led to the search for novel antimicrobials. Antimicrobial peptides (AMPs) derived from scorpion and snake venoms offer an attractive source for the development of novel therapeutics. Smp24 (24 amino acids [aa]) and Smp43 (43 aa) are broad-spectrum AMPs that have been identified from the venom gland of the Egyptian scorpion Scorpio mauruspalmatus and subsequently characterized. Using a DNA microarray approach, we examined the transcriptomic responses of Escherichia coli to subinhibitory concentrations of Smp24 and Smp43 peptides following 5 h of incubation. Seventy-two genes were downregulated by Smp24, and 79 genes were downregulated by Smp43. Of these genes, 14 genes were downregulated in common and were associated with bacterial respiration. Fifty-two genes were specifically upregulated by Smp24. These genes were predominantly related to cation transport, particularly iron transport. Three diverse genes were independently upregulated by Smp43. Strains with knockouts of differentially regulated genes were screened to assess the effect on susceptibility to Smp peptides. Ten mutants in the knockout library had increased levels of resistance to Smp24. These genes were predominantly associated with cation transport and binding. Two mutants increased resistance to Smp43. There was no cross-resistance in mutants resistant to Smp24 or Smp43. Five mutants showed increased susceptibility to Smp24, and seven mutants showed increased susceptibility to Smp43. Of these mutants, formate dehydrogenase knockout (fdnG) resulted in increased susceptibility to both peptides. While the electrostatic association between pore-forming AMPs and bacterial membranes followed by integration of the peptide into the membrane is the initial starting point, it is clear that there are numerous subsequent additional intracellular mechanisms that contribute to their overall antimicrobial effect.IMPORTANCE The development of life-threatening resistance of pathogenic bacteria to the antibiotics typically in use in hospitals and the community today has led to an urgent need to discover novel antimicrobial agents with different mechanisms of action. As an ancient host defense mechanism of the innate immune system, antimicrobial peptides (AMPs) are attractive candidates to fill that role. Scorpion venoms have proven to be a rich source of AMPs. Smp24 and Smp43 are new AMPs that have been identified from the venom gland of the Egyptian scorpion Scorpio maurus palmatus, and these peptides can kill a wide range of bacterial pathogens. By better understanding how these AMPs affect bacterial cells, we can modify their structure to make better drugs in the future.202133980680
843810.9287Virulence of Bacteria Colonizing Vascular Bundles in Ischemic Lower Limbs. BACKGROUND: We documented previously the presence of bacterial flora in vascular bundles, lymphatics, and lymph nodes of ischemic lower limbs amputated because of multifocal atheromatic changes that made them unsuitable for reconstructive surgery and discussed their potential role in tissue destruction. The question arose why bacterial strains inhabiting lower limb skin and considered to be saprophytes become pathogenic once they colonize deep tissues. Bacterial pathogenicity is evoked by activation of multiple virulence factors encoded by groups of genes. METHODS: We identified virulence genes in bacteria cultured from deep tissue of ischemic legs of 50 patients using a polymerase chain reaction technique. RESULTS: The staphylococcal virulence genes fnbA (fibronectin-binding protein A), cna (collagen adhesin precursor), and ica (intercellular adhesion) were present in bacteria isolated from both arteries and, to a lesser extent, skin. The IS256 gene, whose product is responsible for biofilm formation, was more frequent in bacteria retrieved from the arteries than skin bacteria. Among the virulence genes of Staphylococcus epidermidis encoding autolysin atlE, icaAB (intercellular adhesion), and biofilm insert IS256, only the latter was detected in arterial specimens. Bacteria cultured from the lymphatics did not reveal expression of eta and IS256 in arteries. The Enterococcus faecalis asa 373 (aggregation substance) and cylA (cytolysin activator) frequency was greater in arteries than in skin bacteria, as were the E. faecium cyl A genes. All Pseudomonas aeruginosa virulence genes were present in bacteria cultured from both the skin and arteries. Staphylococci colonizing arterial bundles and transported to tissues via ischemic limb lymphatics expressed virulence genes at greater frequency than did those dwelling on the skin surface. Moreover, enterococci and Pseudomonas isolated from arterial bundles expressed many virulence genes. CONCLUSIONS: These findings may add to the understanding of the mechanism of development of destructive changes in lower limb ischemic tissues by the patient's, but not hospital-acquired, bacteria, as well as the generally unsatisfactory results of antibiotic administration in these cases. More aggressive antibiotic therapy targeted at the virulent species should be applied.201626431369
847520.9271Antibacterial Activity of Endophytic Bacteria Against Sugar Beet Root Rot Agent by Volatile Organic Compound Production and Induction of Systemic Resistance. The volatile organic compounds (VOCs) produced by endophytic bacteria have a significant role in the control of phytopathogens. In this research, the VOCs produced by the endophytic bacteria Streptomyces sp. B86, Pantoea sp. Dez632, Pseudomonas sp. Bt851, and Stenotrophomonas sp. Sh622 isolated from healthy sugar beet (Beta vulgaris) and sea beet (Beta maritima) were evaluated for their effects on the virulence traits of Bacillus pumilus Isf19, the causal agent of harvested sugar beet root rot disease. The gas chromatographymass spectrometry (GC-MS) analysis revealed that B86, Dez632, Bt851, and Sh622 produced 15, 28, 30, and 20 VOCs, respectively, with high quality. All antagonistic endophytic bacteria produced VOCs that significantly reduced soft root symptoms and inhibited the growth of B. pumilus Isf19 at different levels. The VOCs produced by endophytic bacteria significantly reduced swarming, swimming, and twitching motility by B. pumilus Isf19, which are important to pathogenicity. Our results revealed that VOCs produced by Sh622 and Bt851 significantly reduced attachment of B. pumilus Isf19 cells to sugar beetroots, and also all endophytic bacteria tested significantly reduced chemotaxis motility of the pathogen toward root extract. The VOCs produced by Dez632 and Bt851 significantly upregulated the expression levels of defense genes related to soft rot resistance. Induction of PR1 and NBS-LRR2 genes in sugar beetroot slices suggests the involvement of SA and JA pathways, respectively, in the induction of resistance against pathogen attack. Based on our results, the antibacterial VOCs produced by endophytic bacteria investigated in this study can reduce soft rot incidence.202235722285
635930.9266Drug resistance of oral bacteria to new antibacterial dental monomer dimethylaminohexadecyl methacrylate. Only two reports exist on drug-resistance of quaternary ammonium monomers against oral bacteria; both studies tested planktonic bacteria for 10 passages, and neither study tested biofilms or resins. The objectives of this study were to investigate the drug-resistance of Streptococcus mutans, Streptococcus sanguinis and Streptococcus gordonii against dimethylaminohexadecyl methacrylate (DMAHDM), and to evaluate biofilms on resins with repeated exposures for 20 passages for the first time. DMAHDM, dimethylaminododecyl methacrylate (DMADDM) and chlorhexidine (CHX) were tested with planktonic bacteria. Biofilms were grown on a resin containing 3% DMAHDM. Minimum-inhibitory concentrations were measured. To detect drug-resistance, the survived bacteria from the previous passage were used as inoculum for the next passage for repeated exposures. S. gordonii developed drug-resistance against DMADDM and CHX, but not against DMAHDM. Biofilm colony-forming units (CFU) on DMAHDM-resin was reduced by 3-4 log; there was no difference from passages 1 to 20 (p > 0.1). No drug-resistance to DMAHDM was detected for all three bacterial species. In conclusion, this study showed that DMAHDM induced no drug-resistance, and DMAHDM-resin reduced biofilm CFU by 3-4 log, with no significant change from 1 to 20 passages. DMAHDM with potent antibacterial activities and no drug-resistance is promising for dental applications.201829615732
636140.9261Vaginal Bacteria in Mares and the Occurrence of Antimicrobial Resistance. Antibiotics are added to semen extenders in insemination doses but their effect on the vaginal microbiota of the inseminated female is unknown. The objectives of this study were to define the equine vaginal microbiota and its antimicrobial resistance, and to determine whether it changes after exposure to antibiotics in semen extenders. Vaginal swabs were taken prior to sham-insemination (day 0), and again on days 3, 7, and 14 after insemination. Isolated bacteria were identified by MALDI-TOF and tested for antimicrobial susceptibility by microdilution. The bacteria isolated from the vagina differed according to reproductive status (brood mare or maiden mare), location (north or middle of Sweden), and the stage of the estrous cycle. Five bacterial species were frequently isolated from mares in both locations: Escherichia coli, Staphylococcus capitis, Streptococcus equisimilis, Streptococcus thoraltensis, and Streptococcus zooepidemicus. Overall, vaginal bacteria isolated from inseminated mares showed higher antibiotic resistance than from non-inseminated mares, suggesting a possible link between exposure to antibiotics in the semen extender and the appearance of antimicrobial resistance. The whole-genome sequencing of E. coli isolates from inseminated mares revealed some genes which are known to confer antimicrobial resistance; however, some instances of resistance in these isolates were not characteristic of induced AMR.202236363796
243850.9259Detection of Staphylococcus aureus and their toxin genes inhabit on the scorpions surface. The transmission of infectious agents by arthropods is of particular importance. Every year, many people are bitten by scorpions around the world. Staphylococcus aureus is of the most important infectious bacteria. This study aimed to investigate the distribution of S. aureus in scorpion specimens and the presence of some toxin genes in these species. The fauna of scorpions in the Kuhdasht region was studied for one year. Then, S. aureus was identified on the body surface of scorpions by biochemical and molecular methods, and the presence of Sea, Seb, Sec, Sed, See, Pvl, Tsst1, Eta, Etb, and mecA genes was examined by the PCR method. The pattern of antibiotic resistance was determined by the use disk diffusion method. MRSA isolates were identified using genotypic and phenotypic methods. Of 75 studied scorpion specimens, Hottentotta saulcyi was the most abundant species. Sixteen (21.3%) isolates of S. aureus were identified from all samples. The highest and lowest antibiotic resistance levels belonged to penicillin and clindamycin, respectively. MRSA was observed in 50% of the isolates. Thirteen out of 16 isolates possessed at least one of the toxin genes. Due to the presence of S. aureus on the body surface of scorpions, it should always be expected that an infection may occur after the bite. Moreover, the presence of toxin genes in the studied isolates showed that infection with these bacteria would seriously threaten one's health.202236018402
999760.9255RNAi screen of DAF-16/FOXO target genes in C. elegans links pathogenesis and dauer formation. The DAF-16/FOXO transcription factor is the major downstream output of the insulin/IGF1R signaling pathway controlling C. elegans dauer larva development and aging. To identify novel downstream genes affecting dauer formation, we used RNAi to screen candidate genes previously identified to be regulated by DAF-16. We used a sensitized genetic background [eri-1(mg366); sdf-9(m708)], which enhances both RNAi efficiency and constitutive dauer formation (Daf-c). Among 513 RNAi clones screened, 21 displayed a synthetic Daf-c (SynDaf) phenotype with sdf-9. One of these genes, srh-100, was previously identified to be SynDaf, but twenty have not previously been associated with dauer formation. Two of the latter genes, lys-1 and cpr-1, are known to participate in innate immunity and six more are predicted to do so, suggesting that the immune response may contribute to the dauer decision. Indeed, we show that two of these genes, lys-1 and clc-1, are required for normal resistance to Staphylococcus aureus. clc-1 is predicted to function in epithelial cohesion. Dauer formation exhibited by daf-8(m85), sdf-9(m708), and the wild-type N2 (at 27°C) were all enhanced by exposure to pathogenic bacteria, while not enhanced in a daf-22(m130) background. We conclude that knockdown of the genes required for proper pathogen resistance increases pathogenic infection, leading to increased dauer formation in our screen. We propose that dauer larva formation is a behavioral response to pathogens mediated by increased dauer pheromone production.201021209831
51970.9255The Ruegeria pomeroyi acuI gene has a role in DMSP catabolism and resembles yhdH of E. coli and other bacteria in conferring resistance to acrylate. The Escherichia coli YhdH polypeptide is in the MDR012 sub-group of medium chain reductase/dehydrogenases, but its biological function was unknown and no phenotypes of YhdH(-) mutants had been described. We found that an E. coli strain with an insertional mutation in yhdH was hyper-sensitive to inhibitory effects of acrylate, and, to a lesser extent, to those of 3-hydroxypropionate. Close homologues of YhdH occur in many Bacterial taxa and at least two animals. The acrylate sensitivity of YhdH(-) mutants was corrected by the corresponding, cloned homologues from several bacteria. One such homologue is acuI, which has a role in acrylate degradation in marine bacteria that catabolise dimethylsulfoniopropionate (DMSP) an abundant anti-stress compound made by marine phytoplankton. The acuI genes of such bacteria are often linked to ddd genes that encode enzymes that cleave DMSP into acrylate plus dimethyl sulfide (DMS), even though these are in different polypeptide families, in unrelated bacteria. Furthermore, most strains of Roseobacters, a clade of abundant marine bacteria, cleave DMSP into acrylate plus DMS, and can also demethylate it, using DMSP demethylase. In most Roseobacters, the corresponding gene, dmdA, lies immediately upstream of acuI and in the model Roseobacter strain Ruegeria pomeroyi DSS-3, dmdA-acuI were co-regulated in response to the co-inducer, acrylate. These observations, together with findings by others that AcuI has acryloyl-CoA reductase activity, lead us to suggest that YdhH/AcuI enzymes protect cells against damaging effects of intracellular acryloyl-CoA, formed endogenously, and/or via catabolising exogenous acrylate. To provide "added protection" for bacteria that form acrylate from DMSP, acuI was recruited into clusters of genes involved in this conversion and, in the case of acuI and dmdA in the Roseobacters, their co-expression may underpin an interaction between the two routes of DMSP catabolism, whereby the acrylate product of DMSP lyases is a co-inducer for the demethylation pathway.201222563425
902880.9243Efflux Pumps in Chromobacterium Species Increase Antibiotic Resistance and Promote Survival in a Coculture Competition Model. Members of the Chromobacterium genus include opportunistic but often-fatal pathogens and soil saprophytes with highly versatile metabolic capabilities. In previous studies of Chromobacterium subtsugae (formerly C. violaceum) strain CV017, we identified a resistance nodulation division (RND)-family efflux pump (CdeAB-OprM) that confers resistance to several antibiotics, including the bactobolin antibiotic produced by the soil saprophyte Burkholderia thailandensis Here, we show the cdeAB-oprM genes increase C. subtsugae survival in a laboratory competition model with B. thailandensis We also demonstrate that adding sublethal bactobolin concentrations to the coculture increases C. subtsugae survival, but this effect is not through CdeAB-OprM. Instead, the increased survival requires a second, previously unreported pump we call CseAB-OprN. We show that in cells exposed to sublethal bactobolin concentrations, the cseAB-oprN genes are transcriptionally induced, and this corresponds to an increase in bactobolin resistance. Induction of this pump is highly specific and sensitive to bactobolin, while CdeAB-OprM appears to have a broader range of antibiotic recognition. We examine the distribution of cseAB-oprN and cdeAB-oprM gene clusters in members of the Chromobacterium genus and find the cseAB-oprN genes are limited to the nonpathogenic C. subtsugae strains, whereas the cdeAB-oprM genes are more widely distributed among members of the Chromobacterium genus. Our results provide new information on the antibiotic resistance mechanisms of Chromobacterium species and highlight the importance of efflux pumps for saprophytic bacteria existing in multispecies communities.IMPORTANCE Antibiotic efflux pumps are best known for increasing antibiotic resistance of pathogens; however, the role of these pumps in saprophytes is much less well defined. This study describes two predicted efflux pump gene clusters in the Chromobacterium genus, which is comprised of both nonpathogenic saprophytes and species that cause highly fatal human infections. One of the predicted efflux pump clusters is present in every member of the Chromobacterium genus and increases resistance to a broad range of antibiotics. The other gene cluster has more narrow antibiotic specificity and is found only in Chromobacterium subtsugae, a subset of entirely nonpathogenic species. We demonstrate the role of both pumps in increasing antibiotic resistance and demonstrate the importance of efflux-dependent resistance induction for C. subtsugae survival in a dual-species competition model. These results have implications for managing antibiotic-resistant Chromobacterium infections and for understanding the evolution of efflux pumps outside the host.201931324628
476190.9241Antimicrobial resistance and biofilm formation of penile prosthesis isolates: insights from in-vitro analysis. BACKGROUND: Inflatable penile prostheses (IPPs) have been shown to harbor biofilms in the presence and absence of infection despite exposure to various antimicrobials. Microbes persisting on IPPs following antibiotic exposure have not been adequately studied to assess biofilm formation capacity and antibiotic resistance. AIM: In this study, we aimed to assess these properties of microbes obtained from explanted infected and non-infected IPPS using an in vitro model. METHODS: 35 bacterial isolates were grown and tested against various single-agent or multiple agent antibiotic regimens including: bacitracin, cefaclor, cefazolin, gentamicin, levofloxacin, trimethoprim-sulfamethoxazole, tobramycin, vancomycin, piperacillin/tazobactam, gentamicin + piperacillin/tazobactam, gentamicin + cefazolin, and gentamicin + vancomycin. Zones of inhibition were averaged for each sample site and species. Statistics were analyzed with Holm's corrected, one-sample t-tests against a null hypothesis of 0. Isolates were also allowed to form biofilms in a 96-well polyvinyl plate and absorbance was tested at 570 nm using a microplate reader. OUTCOMES: Resistance was determined via clinical guidelines or previously established literature, and the mean and standard deviation of biofilm absorbance values were calculated and normalized to the optical density600 of the bacterial inoculum. RESULTS: Every species tested was able to form robust biofilms with the exception of Staphylococcus warneri. As expected, most bacteria were resistant to common perioperative antimicrobial prophylaxis. Gentamicin dual therapy demonstrated somewhat greater efficacy. STRENGTHS AND LIMITATIONS: This study examines a broad range of antimicrobials against clinically obtained bacterial isolates. However, not all species and antibiotics tested had standardized breakpoints, requiring the use of surrogate values from the literature. The microbes included in this study and their resistance genes are expectedly biased towards those that survived antibiotic exposure, and thus reflect the types of microbes which might "survive" in vivo exposure following revisional surgery. CLINICAL TRANSLATION: Despite exposure to antimicrobials, bacteria isolated during penile prosthesis revision for both infected and non-infected cases exhibit biofilm forming capacity and extensive antibiotic resistance patterns in vitro. These microbes merit further investigation to understand when simple colonization vs re-infection might occur. CONCLUSIONS: Although increasing evidence supports the concept that all IPPs harbor biofilms, even in the absence of infection, a deeper understanding of the characteristics of bacteria that survive revisional surgery is warranted. This study demonstrated extensive biofilm forming capabilities, and resistance patterns among bacteria isolated from both non-infected and infected IPP revision surgeries. Further investigation is warranted to determine why some devices become infected while others remain colonized but non-infected.202540062463
8732100.9240RNA-Seq identification of candidate defense genes targeted by endophytic Bacillus cereus-mediated induced systemic resistance against Meloidogyne incognita in tomato. BACKGROUND: The endophytic bacteria Bacillus cereus BCM2 has shown great potential as a defense against the parasitic nematode Meloidogyne incognita. Here, we studied endophytic bacteria-mediated plant defense against M. incognita and searched for defense-related candidate genes using RNA-Seq. RESULTS: The induced systemic resistance of BCM2 against M. incognita was tested using the split-root method. Pre-inoculated BCM2 on the inducer side was associated with a dramatic reduction in galls and egg masses on the responder side, but inoculated BCM2 alone did not produce the same effect. In order to investigate which plant defense-related genes are specifically activated by BCM2, four RNA samples from tomato roots were sequenced, and four high-quality total clean bases were obtained, ranging from 6.64 to 6.75 Gb, with an average of 21 558 total genes. The 34 candidate defense-related genes were identified by pair-wise comparison among libraries, representing the targets for BCM2 priming resistance against M. incognita. Functional characterization revealed that the plant-pathogen interaction pathway (ID: ko04626) was significantly enriched for BCM2-mediated M. incognita resistance. CONCLUSION: This study demonstrates that B. cereus BCM2 maintains a harmonious host-microbe relationship with tomato, but appeared to prime the plant, resulting in more vigorous defense response toward the infection nematode. © 2018 Society of Chemical Industry.201829737595
6369110.9237Association 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
660120.9236Expression of Genes Involved in Bacteriocin Production and Self-Resistance in Lactobacillus brevis 174A Is Mediated by Two Regulatory Proteins. We have previously shown that the lactic acid bacterium Lactobacillus brevis 174A, isolated from Citrus iyo fruit, produces a bacteriocin designated brevicin 174A, which is comprised of two antibacterial polypeptides (designated brevicins 174A-β and 174A-γ). We have also found a gene cluster, composed of eight open reading frames (ORFs), that contains genes for the biosynthesis of brevicin 174A, self-resistance to its own bacteriocin, and two transcriptional regulatory proteins. Some lactic acid bacterial strains have a system to start the production of bacteriocin at an adequate stage of growth. Generally, the system consists of a membrane-bound histidine protein kinase (HPK) that senses a specific environmental stimulus and a corresponding response regulator (RR) that mediates the cellular response. We have previously shown that although the HPK- and RR-encoding genes are not found on the brevicin 174A biosynthetic gene cluster in the 174A strain, two putative regulatory genes, designated breD and breG, are in the gene cluster. In the present study, we demonstrate that the expression of brevicin 174A production and self-resistance is positively controlled by two transcriptional regulatory proteins, designated BreD and BreG. BreD is expressed together with BreE as the self-resistance determinant of L. brevis 174A. DNase I footprinting analysis and a promoter assay demonstrated that BreD binds to the breED promoter as a positive autoregulator. The present study also demonstrates that BreG, carrying a transmembrane domain, binds to the common promoter of breB and breC, encoding brevicins 174A-β and 174A-γ, respectively, for positive regulation.IMPORTANCE The problem of the appearance of bacteria that are resistant to practical antibiotics and the increasing demand for safe foods have increased interest in replacing conventional antibiotics with bacteriocin produced by the lactic acid bacteria. This antibacterial substance can inhibit the growth of pathogenic bacteria without side effects on the human body. The bacteriocin that is produced by a Citrus iyo-derived Lactobacillus brevis strain inhibits the growth of pathogenic bacteria such as Listeria monocytogenes, Staphylococcus aureus, and Streptococcus mutans In general, lactic acid bacterial strains have a system to start the production of bacteriocin at an adequate stage of growth, which is called a quorum-sensing system. The system consists of a membrane-bound histidine protein kinase that senses a specific environmental stimulus and a corresponding response regulator that mediates the cellular response. The present study demonstrates that the expression of the genes encoding bacteriocin biosynthesis and the self-resistance determinant is positively controlled by two transcriptional regulatory proteins.201829352085
662130.9235Gene expression and physiological role of Pseudomonas aeruginosa methionine sulfoxide reductases during oxidative stress. Pseudomonas aeruginosa PAO1 has two differentially expressed methionine sulfoxide reductase genes: msrA (PA5018) and msrB (PA2827). The msrA gene is expressed constitutively at a high level throughout all growth phases, whereas msrB expression is highly induced by oxidative stress, such as sodium hypochlorite (NaOCl) treatment. Inactivation of either msrA or msrB or both genes (msrA msrB mutant) rendered the mutants less resistant than the parental PAO1 strain to oxidants such as NaOCl and H2O2. Unexpectedly, msr mutants have disparate resistance patterns when exposed to paraquat, a superoxide generator. The msrA mutant had a higher paraquat resistance level than the msrB mutant, which had a lower paraquat resistance level than the PAO1 strain. The expression levels of msrA showed an inverse correlation with the paraquat resistance level, and this atypical paraquat resistance pattern was not observed with msrB. Virulence testing using a Drosophila melanogaster model revealed that the msrA, msrB, and, to a greater extent, msrA msrB double mutants had an attenuated virulence phenotype. The data indicate that msrA and msrB are essential genes for oxidative stress protection and bacterial virulence. The pattern of expression and mutant phenotypes of P. aeruginosa msrA and msrB differ from previously characterized msr genes from other bacteria. Thus, as highly conserved genes, the msrA and msrB have diverse expression patterns and physiological roles that depend on the environmental niche where the bacteria thrive.201323687271
6079140.9233Genomic 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
6162150.9233The resistance of BALB/cJ mice to Yersinia pestis maps to the major histocompatibility complex of chromosome 17. Yersinia pestis, the causative agent of plague, has been well studied at the molecular and genetic levels, but little is known about the role that host genes play in combating this highly lethal pathogen. We challenged several inbred strains of mice with Y. pestis and found that BALB/cJ mice are highly resistant compared to susceptible strains such as C57BL/6J. This resistance was observed only in BALB/cJ mice and not in other BALB/c substrains. Compared to C57BL/6J mice, the BALB/cJ strain exhibited reduced bacterial burden in the spleen and liver early after infection as well as lower levels of serum interleukin-6. These differences were evident 24 h postinfection and became more pronounced with time. Although a significant influx of neutrophils in the spleen and liver was exhibited in both strains, occlusive fibrinous thrombi resulting in necrosis of the surrounding tissue was observed only in C57BL/6J mice. In an effort to identify the gene(s) responsible for resistance, we measured total splenic bacteria in 95 F(2) mice 48 h postinfection and performed quantitative trait locus mapping using 58 microsatellite markers spaced throughout the genome. This analysis revealed a single nonrecessive plague resistance locus, designated prl1 (plague resistance locus 1), which coincides with the major histocompatibility complex of chromosome 17. A second screen of 95 backcrossed mice verified that this locus confers resistance to Y. pestis early in infection. Finally, eighth generation backcrossed mice harboring prl1 were found to maintain resistance in the susceptible C57BL/6J background. These results identify a novel genetic locus in BALB/cJ mice that confers resistance to Y. pestis.200818573896
3065160.9233Species diversity, virulence, and antimicrobial resistance of the nasal staphylococcal and mammaliicoccal biota of reindeer. BACKGROUND: Staphylococcus (S.) spp. and Mammaliicoccus (M.) spp., in addition to their established role as components of the human and animal microbiota, can also cause opportunistic infections. This study aimed to characterize bacteria recovered from nasal cavities of healthy adult reindeer from two farms located in Poland (15 reindeer) and Germany (15 reindeer). The research include bacteria isolation, species identification, detection of selected superantigen (SAg) genes, assessment of biofilm-forming capability in vitro, and evaluation of antimicrobial resistance. RESULTS: Seventy-four staphylococci and mammaliicocci from 14 different species were isolated from 30 nasal swabs, with one to four strains obtained from each reindeer. The most frequently identified species was S. equorum, followed by S. succinus, M. sciuri, S. xylosus, M. lentus, S. chromogenes, S. devriesei, M. vitulinus, S. auricularis, S. agnetis, S. edaphicus, S. petrasii, S. simulans, and S. warneri. A greater species diversity was observed among the reindeer from Poland compared to those from Germany. All isolated bacteria were coagulase negative and clumping factor negative and did not carry any of the 21 analyzed SAg genes. M. sciuri demonstrated the highest antimicrobial resistance (100%), followed by S. succinus (91%) and S. equorum (78%). Resistance to rifampicin was the most common (30% strains). Sixteen strains (22%) exhibited biofilm production at least 10% greater than the strong biofilm-forming S. aureus ATCC 6538. CONCLUSIONS: This study reveals a significant knowledge gap regarding the nasal microbiota of reindeer. It contributes to our understanding of staphylococcal and mammaliicoccal biota of reindeer and underscores the necessity for monitoring of microbial populations to assess their health implications for both animals and humans, particularly concerning the zoonotic transmission of bacteria.202540452044
613170.92294-Hydroxy-2-nonenal antimicrobial toxicity is neutralized by an intracellular pathogen. Pathogens encounter numerous antimicrobial responses during infection, including the reactive oxygen species (ROS) burst. ROS-mediated oxidation of host membrane poly-unsaturated fatty acids (PUFAs) generates the toxic alpha-beta carbonyl 4-hydroxy-2-nonenal (4-HNE). Although studied extensively in the context of sterile inflammation, research into 4-HNE's role during infection remains limited. Here, we found that 4-HNE is generated during bacterial infection, that it impacts growth and survival in a range of bacteria, and that the intracellular pathogen Listeria monocytogenes induces many genes in response to 4-HNE exposure. A component of the L. monocytogenes 4-HNE response is the expression of the genes lmo0103 and lmo0613, deemed rha1 and rha2 (reductase of host alkenals), respectively, which code for two NADPH-dependent oxidoreductases that convert 4-HNE to the product 4-hydroxynonanal (4-HNA). Loss of these genes had no impact on L. monocytogenes bacterial burdens during murine or tissue culture infection. However, heterologous expression of rha1/2 in Bacillus subtilis significantly increased bacterial resistance to 4-HNE in vitro and promoted bacterial survival following phagocytosis by murine macrophages in an ROS-dependent manner. Thus, Rha1 and Rha2 are not necessary for 4-HNE resistance in L. monocytogenes but are sufficient to confer resistance to an otherwise sensitive organism in vitro and in host cells. Our work demonstrates that 4-HNE is a previously unappreciated component of ROS-mediated toxicity encountered by bacteria within eukaryotic hosts.202133955352
6134180.9228Complete genome and gene expression analyses of Asaia bogorensis reveal unique responses to culture with mammalian cells as a potential opportunistic human pathogen. Asaia bogorensis, a member of acetic acid bacteria (AAB), is an aerobic bacterium isolated from flowers and fruits, as well as an opportunistic pathogen that causes human peritonitis and bacteraemia. Here, we determined the complete genomic sequence of the As. bogorensis type strain NBRC 16594, and conducted comparative analyses of gene expression under different conditions of co-culture with mammalian cells and standard AAB culture. The genome of As. bogorensis contained 2,758 protein-coding genes within a circular chromosome of 3,198,265 bp. There were two complete operons encoding cytochrome bo3-type ubiquinol terminal oxidases: cyoABCD-1 and cyoABCD-2. The cyoABCD-1 operon was phylogenetically common to AAB genomes, whereas the cyoABCD-2 operon belonged to a lineage distinctive from the cyoABCD-1 operon. Interestingly, cyoABCD-1 was less expressed under co-culture conditions than under the AAB culture conditions, whereas the converse was true for cyoABCD-2. Asaia bogorensis shared pathogenesis-related genes with another pathogenic AAB, Granulibacter bethesdensis, including a gene coding pathogen-specific large bacterial adhesin and additional genes for the inhibition of oxidation and antibiotic resistance. Expression alteration of the respiratory chain and unique hypothetical genes may be key traits that enable the bacterium to survive under the co-culture conditions.201526358298
5175190.9227In vitro and in vivo evaluation of probiotic properties of Corynebacterium accolens isolated from the human nasal cavity. Corynebacterium accolens strains are increasingly recognized as beneficial bacteria that can confer a health benefit on the host. In the current study, the probiotic potential of three C. accolens strains, C779, C781 and C787 derived from a healthy human nasal cavity were investigated. These strains were examined for their adhesion to HNECs, competition with Staphylococcus aureus for adhesion, toxicity, induction of IL-6, antibiotic susceptibility and the presence of antibiotic resistance and virulence genes. Furthermore, the safety and efficacy of strains were evaluated in vivo using Caenorhabditis elegans. The adhesion capacity of C. accolens to HNECs was strain-dependent. Highest adhesion was observed for strain C781. None of the C. accolens strains tested caused cell lysis. All strains were able to outcompete S. aureus for cell adhesion and caused a significant decrease of IL-6 production by HNECs co-exposed to S. aureus when compared to the control groups. All strains were sensitive or showed intermediate sensitivity to 10 different antibiotics. Whole Genome Sequence analysis showed C. accolens C781 and C787 did not possess antibiotic resistance genes whereas strain C779 harboured 5 genes associated with resistance to Aminoglycoside, Chloramphenicol and Erythromycin. In addition, no virulence genes were detected in any of the 3 strains. Moreover, the tested strains had no detrimental effect on worm survival and induced protection from S. aureus-mediated infection. Taken all together, C. accolens strains, C781 and C787 displayed probiotic potential and hold promise for use in clinical applications for combating dysbiosis in chronic rhinosinusitis.202234875424