Peptidoglycan Research Articles

The relationship between resistance evolution and carbon metabolism in Staphylococcus xylosus under ceftiofur sodium stress.

Staphylococcus xylosus has emerged as a bovine mastitis pathogen with increasing drug resistance, resulting in substantial economic impacts. This study utilized iTRAQ analysis to investigate the mechanisms driving resistance evolution in S. xylosus under ceftiofur sodium stress. Findings revealed notable variations in the expression of 143 proteins, particularly glycolysis-related proteins (TpiA, Eno, GlpD, Ldh) and peptidoglycan (PG) hydrolase Atl. Following the induction of ceftiofur sodium resistance in S. xylosus, the emergence of resistant strains displaying characteristics of small colony variants (SCVs) was observed. The transcript levels of TpiA, Eno, GlpD and Ldh were up-regulated, TCA cycle proteins (ICDH, MDH) and Atl were down-regulated, lactate content was increased, and NADH concentration was decreased in SCV compared to the wild strain. That indicates a potential role of carbon metabolism, specifically PG hydrolysis, glycolysis, and the TCA cycle, in the development of resistance to ceftiofur sodium in S. xylosus.

Characteristics and functional analysis of a novel mannose receptor in Penaeus vannamei

The mannose receptor (MR) plays a key role in the innate immune system as a pattern recognition receptor. Here, a novel type of mannose receptor, named PvMR2, was identified from Penaeus vannamei (P. vannamei). The PvMR2 coding sequence (CDS) obtained was 988 base pairs in length, encoding a protein consisting of 328 amino acids. This protein includes a signal peptide and two classical C-type lectin domains (CTLD). Quantitative real-time PCR showed that PvMR2 was distributed in all detected tissues, with the highest levels in the intestines and stomach. Following a bacterial challenge with Vibrio anguillarum (V. anguillarum), PvMR2 showed significant up-regulation in both the intestines and stomach of shrimp. To validate the function of PvMR2, recombinant proteins were extracted and purified using a His-tag. The resulting rPvMR2 demonstrated binding capability with lipopolysaccharides (LPS) and peptidoglycan (PGN) in a dose-dependent manner, affirming its binding affinity. The purified rPvMR2 demonstrated calcium-independent binding activity towards both Gram-positive bacteria (V. anguilliarum and Vibrio parahaemolyticus) and Gram-negative bacteria (Escherichia coli and Aeromonas Veronii). Antibacterial assays confirmed that rPvMR2 inhibits bacterial growth. Intestinal adhesion and adhesion inhibition experiments confirmed that the rPvMR2 can be used to reduce the adhesion capacity of harmful bacteria in the gut. Phagocytosis experiments have shown that rPvMR2 promotes phagocytosis in hemocytes and protects the host from external infection. Treatment with recombinant PvMR2 significantly bolstered bacterial clearance within the hemolymph and markedly augmented shrimp survival post-infection with V. anguillarum. These results suggest that PvMR2 has agglutination, growth inhibition, adhesion inhibition, clearance promotion, and phagocytosis effects on harmful bacteria, and plays a crucial role in the antimicrobial immune response of P. vannamei.

GRAM-POSITIVE BACTERIA WITHIN THE INTERVERTEBRAL DISC AND THEIR POTENTIAL INFLUENCE

IntroductionMultiple studies have identified Cutibacterium acnes (C.acnes) and other microbes in intervertebral disc tissue using 16S DNA Sequencing and microbial cultures. However, it remains unclear whether these bacteria are native to the discs or result from perioperative contamination. Our study aimed to detect Gram-positive bacteria in non-herniated human disc samples and explore correlations with Toll-like receptors (TLR) 2, TLR4, NLRP3, and Gasdermin D.MethodsImmunohistochemical staining was conducted on 75 human IVD samples for Gram-positive bacteria, S. aureus, C.acnes, TLR2, TLR4, NLRP3, and Gasdermin D. Cell detection and classification were performed using QuPath. NP cells were treated with Lipopolysaccharide (LPS) and Peptidoglycan (PGN) in monolayer and alginate beads for up to 72 hours, followed by secretome analysis using Luminex. Statistical analysis included Kruskal-Wallis, Dunn's multiple comparison test, and Pearson correlation.ResultsImmunohistochemical staining revealed Gram-positive bacteria exclusively within cells, with C. acnes positivity ranging from 5–99% and correlating with patient age (r=0.41, p= 0.007). TLR2 positivity ranged from 5–99% and TLR4 from 3–72%, showing a strong correlation (r= 0.62, p= 1.5e-006). Females with mid-degenerative grades exhibited significantly decreased TLR2 expression compared to those without degeneration signs. Treatment with LPS and PGN increased catabolic cyto- and chemokines associated with IVD degeneration.ConclusionIn conclusion, this study confirms Gram-positive bacteria presence in non-herniated human disc samples and highlights their role in triggering a catabolic response in disc cells.No conflicts of interest Sources of fundingThis project is part of the Disc4All Training network to advance integrated computational simulations in translational medicine, applies to intervertebral disc degeneration and funded by Horizon 2020 (H2020-MSCA-ITN-ETN-2020 GA: 955735)

The intrinsic macrolide resistome of Escherichia coli.

Intrinsic resistance to macrolides in Gram-negative bacteria is primarily attributed to the low permeability of the outer membrane, though the underlying genetic and molecular mechanisms remain to be fully elucidated. Here, we used transposon directed insertion-site sequencing (TraDIS) to identify chromosomal non-essential genes involved in Escherichia coli intrinsic resistance to a macrolide antibiotic, tilmicosin. We constructed two highly saturated transposon mutant libraries of >290,000 and >390,000 unique Tn5 insertions in a clinical enterotoxigenic strain (ETEC5621) and in a laboratory strain (K-12 MG1655), respectively. TraDIS analysis identified genes required for growth of ETEC5621 and MG1655 under 1/8 MIC (n = 15 and 16, respectively) and 1/4 MIC (n = 38 and 32, respectively) of tilmicosin. For both strains, 23 genes related to lipopolysaccharide biosynthesis, outer membrane assembly, the Tol-Pal system, efflux pump, and peptidoglycan metabolism were enriched in the presence of the antibiotic. Individual deletion of genes (n = 10) in the wild-type strains led to a 64- to 2-fold reduction in MICs of tilmicosin, erythromycin, and azithromycin, validating the results of the TraDIS analysis. Notably, deletion of surA or waaG, which impairs the outer membrane, led to the most significant decreases in MICs of all three macrolides in ETEC5621. Our findings contribute to a genome-wide understanding of intrinsic macrolide resistance in E. coli, shedding new light on the potential role of the peptidoglycan layer. They also provide an in vitro proof of concept that E. coli can be sensitized to macrolides by targeting proteins maintaining the outer membrane such as SurA and WaaG.

Nascent flagellar basal bodies are immobilized by rod assembly in Bacillus subtilis.

Bacteria insert flagella in a species-specific pattern on the cell body, but how patterns are achieved is poorly understood. In bacteria with a single polar flagellum, a marker protein localizes to the cell pole and nucleates the assembly of the flagellum at that site. Bacillus subtilis assembles ∼15 flagella over the length of the cell body in a grid-like pattern and lacks all proteins associated with targeted assembly in polarly flagellated bacteria. Here we show that B. subtilis basal bodies are mobile soon after assembly and become immobilized when the flagellar rod transits the peptidoglycan wall. Moreover, defects in the flagellar rod lead to an asymmetric distribution of flagella with respect to the midcell. We conclude that the patterning of flagella is different in B. subtilis , and we infer that the B. subtilis rod probes the peptidoglycan for holes that can accommodate the machine.

Atacama desert is a source of new Micromonospora strains: description of Micromonospora sicca sp. nov

Several strains were isolated from subsurface soil of the Atacama Desert and were previously assigned to the Micromonospora genus. A polyphasic study was designed to determine the taxonomic affiliation of isolates 4G51T, 4G53, and 4G57. All the strains showed chemotaxonomic properties in line with their classification in the genus Micromonospora, including meso-diaminopimelic acid in the cell wall peptidoglycan, MK-9(H4) as major respiratory quinone, iso-C15:0 and iso-C16:0 as major fatty acids and diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol as major polar lipids. The 16S rRNA gene sequences of strains 4G51T, 4G53, and 4G57 showed the highest similarity (97.9 %) with the type strain of Micromonospora costi CS1-12T, forming an independent branch in the phylogenetic gene tree. Their independent position was confirmed with genome phylogenies, being most closely related to the type strain of Micromonospora kangleipakensis. Digital DNA-DNA hybridization and average nucleotide identity analyses between the isolates and their closest phylogenomic neighbours confirmed that they should be assigned to a new species within the genus Micromonospora for which the name Micromonospora sicca sp. nov. (4G51T=PCM 3031T=LMG 30756T) is proposed.

Abstract Tu022: Gut-derived bacterial metabolites promote cardiac inflammation, leading to heart failure in murine model of DSS-induced colitis

Background: Inflammatory Bowel Disease (IBD) affects millions of people all over the world. This has been known to contribute to several other comorbidities. Recently, impaired gut-barrier permeability has been known to contribute to cardiovascular diseases in IBD patients. However, the precise mechanisms remain unclear. In this study, we propose that bacterial metabolites, like peptidoglycan, may play a role in promoting cardiac inflammation and ultimately leading to heart failure in mice following colitis. Methods: We induced colitis in C57 black mice with DSS (dextran sodium sulfate) treatment. Further, we collected fecal sample for 16s rRNA analysis to evaluate microbial flora. Additionally, heart and intestine tissues were collected to determine inflammatory genes expression (qPCR), immune cell infiltration (FACS), and intestinal permeability (WB and immunohistochemistry). Blood was collected to quantify the circulating peptidoglycan (PGN) level. The effect of PGN on NFkB inflammatory pathways was evaluated in macrophages. Results: Echo-data showed cardiac dysfunction in DSS mice. Masson’s trichrome staining showed deteriorated intestinal villi, while western blot data indicated decreased Occludin and increased PV-1 level, suggesting a leaky gut in DSS treated mice. Comparative analysis of 16s rRNA sequencing data showed significantly altered Firmicutes/Bacteroidetes ratio in DSS treated mice as compared to control mice. Moreover, plasma PGN level was significantly increased 3 weeks following DSS treatment. Real-time gene expression data of pro-inflammatory cytokines (TNFα) and fibrosis associated genes (col1α1, fibronectin) were increased in DSS mice heart. Increased CD68 expression in the immunostaining data of DSS mice heart suggests the recruitment of inflammatory macrophages. At the molecular level, CDK9 expression was significantly increased in macrophage following PGN treatment, which ultimately leads to an increase in NFkB signaling. Finally, CDK9 inhibition attenuated PGN-induced NFkB signaling. Conclusion: Together, our study suggests that colitis-induced gut leakage leads to CDK9-mediated NFκB upregulation, contributing to cardiac inflammation. Ongoing research will shed light on the underlying molecular mechanisms of cardiovascular dysfunction.

The MarR family regulator RmaH mediates acid tolerance of Lactococcus lactis through regulating peptidoglycan modification genes

Lactococcus lactis, widely used in the food fermentation industry, has developed various ways to regulate acid adaptation in the process of evolution. The investigation into how peptidoglycan (PG) senses and responds to acid stress is an expanding field. Here, we addressed the regulation of murT-gatD genes which are responsible for the amidation of PG D-Glu. We found that lactic acid stress reduced murT-gatD expression, and overexpressing these genes notably decreased acid tolerance of L. lactis NZ9000, possibly due to a reduction in PG's negative charge, facilitating the influx of extracellular protons into the cell. Subsequently, using a combination of DNA pull-down assay and electrophoretic mobility shift assay (EMSA), we identified a novel MarR family regulator, RmaH, as an activator of murT-gatD transcription. Further MEME motif prediction, EMSA verification and fluorescent protein reporter assay showed that RmaH directly bound to the DNA motif 5'-KGVAWWTTTTGCT-3' located in the upstream region of murT-gatD. Beyond the mechanistic investigation of RmaH activation of murT-gatD, this study provides new insight into how peptidoglycan modification is regulated and responds to lactic acid stress.

Construing the function of N-terminal domain of D29 mycobacteriophage LysA endolysin in phage lytic efficiency and proliferation.

Endolysins produced by bacteriophages hydrolyze host cell wall peptidoglycan to release newly assembled virions. D29 mycobacteriophage specifically infects mycobacteria including the pathogenic Mycobacterium tuberculosis. D29 encodes LysA endolysin, which hydrolyzes mycobacterial cell wall peptidoglycan. We previously showed that LysA harbors two catalytic domains (N-terminal domain [NTD] and lysozyme-like domain [LD]) and a C-terminal cell wall binding domain (CTD). While the importance of LD and CTD in mycobacteriophage biology has been examined in great detail, NTD has largely remained unexplored. Here, to address NTD's significance in D29 physiology, we generated NTD-deficient D29 (D29∆NTD) by deleting the NTD-coding region from D29 genome using CRISPY-BRED. We show that D29∆NTD is viable, but has a longer latent period, and a remarkably reduced burst size and plaque size. A large number of phages were found to be trapped in the host during the D29∆NTD-mediated cell lysis event. Such poor release of progeny phages during host cell lysis strongly suggests that NTD-deficient LysA produced by D29∆NTD, despite having catalytically-active LD, is unable to efficiently lyse host bacteria. We thus conclude that LysA NTD is essential for optimal release of progeny virions, thereby playing an extremely vital role in phage physiology and phage propagation in the environment.

Actinomycetospora aeridis sp. nov., Actinomycetospora flava sp. nov. and Actinomycetospora aurantiaca sp. nov., endophytic actinobacteria isolated from wild orchid (Aerides multiflora Roxb).

Three novel mycelium-forming actinobacteria, designated OC33-EN06T, OC33-EN07T, and OC33-EN08T, were isolated from wild orchid (Aerides multiflora Roxb), collected from a hill evergreen forest in Northern Thailand. Strains OC33-EN06T and OC33-EN07T showed the highest 16S rRNA gene similarity with Actinomycetospora lutea TT00-04T, 99.17 and 99.45%, respectively. Strain OC33-EN08T showed high similarity with four species, namely 'Actinomycetospora termitidis Odt1-22T' (99.37%), Actinomycetospora chiangmaiensis DSM 45062T (99.02%), Actinomycetospora corticicola 014-5T (99.02%), and Actinomycetospora soli SF1T (98.81%). Comparative genome analysis of OC33-EN06T, OC33-EN07T, and OC33-EN08T with the closely related type strains showed that average nucleotide identity (ANI) based on blast, ANI based on MUMmer, and average amino acid identity values were less than 95% and the digital DNA-DNA hybridization values were less than 70%, all below the thresholds for species demarcation. The digital G+C content of OC33-EN06T, OC33-EN07T, and OC33-EN08T were 74.5, 74, and 74 mol%, respectively. These three strains developed bud-like chains of non-motile cylindrical spores with a smooth surface. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, arabinose, and galactose. The predominant menaquinone was MK-8(H4). The phospholipid profile included phosphatidylcholine, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylinositol. Based on comparative analysis of genotypic, phenotypic and chemotaxonomic data, strains OC33-EN06T (=TBRC 18349T=NBRC 116543T), OC33-EN07T (=TBRC 18350T=NBRC 116544T), and OC33-EN08T (=TBRC 18318T=NBRC 116542T) represent the type strains of three novel species of the genus Actinomycetospora for which the names Actinomycetospora aeridis sp. nov., Actinomycetospora flava sp. nov., and Actinomycetospora aurantiaca sp. nov., are proposed.

Vagococcus jeotgali sp. nov., isolated from cutlassfish jeotgal, a traditional Korean fermented seafood.

A novel, Gram-positive, facultatively anaerobic, and non-motile bacterial strain, designated B2T-5T, was isolated from jeotgal, a traditional Korean fermented seafood. Colonies grown on gifu anaerobic medium agar plates were cream-coloured, irregular, and umbonate with curled margins. Optimal growth of strain B2T-5T occurred at 20 °C, pH 8.0, and in the presence of 1% (w/v) NaCl. Strain B2T-5T was negative for oxidase and catalase activity. Hippurate was not hydrolysed and acetoin was not produced. The major cellular fatty acids were C18 : 1 ω9c and C16 : 0. The cell-wall peptidoglycan was of the A4α type containing l-Lys-d-Asp. The predominant respiratory quinone was menaquinone 7. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylcholine. According to the phylogenetic analysis based on 16S rRNA gene sequences, strain B2T-5T was most closely related to Vagococcus teuberi DSM 21459T, showing 98.2% sequence similarity. Genome sequencing of strain B2T-5T revealed a genome size of 2.0 Mbp and a G+C content of 33.8 mol%. The average nucleotide identities of strain B2T-5T with Vagococcus teuberi DSM 21459T, Vagococcus bubulae SS1994T, and Vagococcus martis D7T301T were 75.0, 74.7, and 75.1%, respectively. Based on the phenotypic, chemotaxonomic, and genotypic data, strain B2T-5T represents a novel species of the genus Vagococcus, for which the name Vagococcus jeotgali sp. nov. is proposed. The type strain is B2T-5T (=KCTC 21223T=JCM 35937T).

Comparative effects of dietary muramidase and phytogenics on the growth performance and gastrointestinal functionality of broiler chickens

The objective of the present study was to compare the effectiveness of dietary supplementation of muramidase (MUR) and 2 phytogenic additives on the growth performance, intestinal morphology, bacteria load, and production of short-chain fatty acids (SCFA) of broiler chickens raised under field-like conditions. A total of 6,400 day-old Ross 308 broiler chicks were randomly selected and distributed into 32 floor pens, with 200 chicks (100 males and 100 females)/pen. The treatment groups were an unsupplemented control, and the experimental groups supplemented with MUR at 35,000 LSU(F)/kg of feed, phytogenic 1 (Phyto 1, based on thymol) at 100g/ton feed, or phytogenic 2 (Phyto 2, based on alkaloids) at 60g/ton feed, for a total period of 41 d. A 4-phase feeding program was applied (starter, grower, finisher and withdrawal). The paramenters evaluated were: growth performance, carcass yield, concentration of muranic acid in the jejunum content and excreta, liver enzyme concentration, intestinal morphology, and bacteria enumeration and short and branch chain fatty acids (SCFA and BCFA) in the cecal content. Data were analyzed by ANOVA and Tukey's test was used to separate the means. Soluble muramic acid (MurN) in the jejunum increased with the supplementation of MUR and Phyto 2 when compared to the other groups (P = 0.0001), but only the supplementation of MUR increased the concentration of MurN in the excreta. The supplementation of all feed additives improved the body weight gain and the body weight corrected feed conversion ratio when compared to the control group (P = 0.0001). MUR increased villus heigh (VH) when compared to the control or the other supplemented groups (P = 0.0001), and led to the highest concentration of most SCFA, total BCFA, and total SCFA (P < 0.05). In conclusion, the supplementation of MUR and phytogenics to the diets of broiler chickens improved the growth performance, but MUR, only, was capable of effectively degrading peptidoglycans (PGNs) in both intestinal segments, as well as to increase the abundance of beneficial bacteria and SCFA production.

Antagonistic Effects and the Underlying Mechanisms of Bacillus velezensis and its Antibacterial Peptide LCI Against Aeromonas hydrophila Infection in Largemouth Bass.

Aeromonas hydrophila is one of the most prevalent pathogenic bacteria in largemouth bass. The use of antibiotics to inhibit A. hydrophila poses a significant threat to fish and environmental safety. Bacillus velezensis, a safe bacterium with probiotic and antibacterial characteristics, is an ideal candidate for antagonizing A. hydrophila. This study explored the antagonistic effects of B. velezensis FLU-1 on A. hydrophila in vivo and in vitro. In addition, we explored the antimicrobial peptides (AMPs) produced by strain FLU-1 and clarified the underlying antibacterial mechanisms. The results showed that strain FLU-1 could inhibit a variety of fish pathogens, including A. hydrophila. The challenge test showed that dietary supplementation with B. velezensis FLU-1 significantly improved the survival rate of largemouth bass and reduced the bacterial load in liver. Subsequently, the AMP LCI was isolated from B. velezensis FLU-1 and was found to be effective against A. hydrophila in vitro and in vivo. Transcriptomic analysis revealed that LCI downregulated the genes associated with flagellar assembly and peptidoglycan synthesis in A. hydrophila. Phenotypic test results showed that LCI disrupted the membrane integrity, markedly reduced the biofilm biomass and diminished the swimming motility of A. hydrophila. Furthermore, the results showed that LCI bound to the genomic DNA of A. hydrophila and destroyed the DNA structures. Overall, these findings elucidated the mechanism of action of LCI against A. hydrophila at the phenotypic and physiological levels. This study suggests that B. velezensis FLU-1 and its AMP LCI could serve as antibiotic alternatives for controlling pathogens in aquaculture.

Effect of the interlayer distribution of ZnO decorated with Ag nanoparticles on the antimicrobial activity of multilayer poly(methyl methacrylate) films

AbstractIncorporating nanoparticles into polymer matrices for enhanced antimicrobial properties is particularly interesting. This study examines how the interlayer distribution of zinc oxide (ZnO) decorated with silver nanoparticles (AgNPs) within poly(methyl methacrylate) (PMMA) films impacts their antimicrobial activity. Various PMMA multilayer films were prepared, with the antimicrobial additive intentionally placed in the outer, core, bottom, or throughout all layers. Their efficacy was tested against gram‐negative (Escherichia coli) and gram‐positive (Staphylococcus aureus) bacteria. Results indicate that E. coli was the strain with the highest sensitivity to the system because it is a gram (−) bacterium, which could generate a lower resistance to AgNPs. On the other hand, S. aureus, being gram (+), presents a thicker lipid membrane, and peptidoglycan wall, which makes it difficult for AgNPs to enter. Films with uniform distribution throughout thickness exhibited the most sustained antimicrobial activity due to high antimicrobial concentration. This study demonstrated that the distribution of the AgNPs/ZnO system in different layers of a PMMA film influences its antimicrobial capacity. Finally, a mechanism for migrating silver ions released from the AgNPs/ZnO system in PMMA films is proposed, highlighting their interactions with bacterial cells and the subsequent antimicrobial effects.Highlights Interlayer distribution influences antimicrobial activity. Outer placement leads to rapid silver ion release. Core distribution controls antimicrobial kinetics. Uniform distribution ensures sustained activity.

HLA-DR-Expressing Fibroblast-Like Synoviocytes Are Inducible Antigen Presenting Cells That Present Autoantigens in Lyme Arthritis.

HLA-DR-expressing fibroblast-like synoviocytes (FLS) are a prominent cell type in synovial tissue in chronic inflammatory forms of arthritis. FLS-derived extracellular matrix (ECM) proteins, including fibronectin-1 (FN1), contain immunogenic CD4+ T cell epitopes in patients with postinfectious Lyme arthritis (LA). However, the role of FLS in presentation of these T cell epitopes remains uncertain. Primary LA FLS and primary murine FLS stimulated with interferon gamma (IFNγ), Borrelia burgdorferi, and/or B burgdorferi peptidoglycan (PG) were assessed for properties associated with antigen presentation. HLA-DR-presented peptides from stimulated LA FLS were identified by immunopeptidomics analysis. OT-II T cells were co-cultured with stimulated murine FLS in the presence of cognate ovalbumin antigen to determine the potential of FLS to act as inducible antigen presenting cells (APCs). FLS expressed HLA-DR molecules within inflamed synovial tissue and tendons from patients with postinfectious LA in situ. Major histocompatibility complex (MHC) class II and co-stimulatory molecules were expressed by FLS following in vitro stimulation with IFNγ and B burgdorferi and presented both foreign and self-MHC-II peptides, including an immunogenic T cell epitope derived from Lyme autoantigen FN1. Stimulated FLS induced proliferation of naive OT-II CD4+ T cells that were dependent on OT-II antigen and CD40. Stimulation with B burgdorferi PG enhanced FLS-mediated T cell activation. MHC-II+ FLS are inducible APCs that can induce CD4+ T cell activation in an antigen- and CD40-dependent manner. Activated FLS can also present ECM-derived Lyme autoantigens, implicating FLS in amplifying tissue-localized autoimmunity in LA.

Chengkuizengella axinellae sp. nov., a symbiotic bacterium isolated from a marine sponge of the genus Axinella.

A Gram-stain-positive, strictly aerobic, creamy-white colored, endospore-forming and non-motile rods strain, designated as strain 2205SS18-9T, was isolated from a marine sponge, Axinella sp. collected from Seopseom Island, Republic of Korea. Optimal growth of strain 2205SS18-9T was observed at 25-30°C, pH 6.5-7.0, and in the presence of 3.0% (w/v) NaCl. Cells were oxidase-positive and catalase-negative. Negative for nitrate reduction and indole production. Phylogenetic analyses based on the 16S rRNA gene and whole-genome sequences revealed that strain 2205SS18-9T formed a distinct phyletic lineage in the genus Chengkuizengella, and it was most closely related to Chengkuizengella marina YPA3-1-1T and Chengkuizengella sediminis J15A17T with 97.1 and 96.6% 16S rRNA gene sequence similarities, respectively. The average nucleotide identity and digital DNA-DNA hybridization values between strain 2205SS18-9T and Chengkuizengella marina YPA3-1-1T were 79.0 and 21.6%, respectively. The genomic DNA G + C content was 34.1%. The genome harbors a number of host-adhesion and transporter genes, suggested that strain 2205SS18-9T may interact with its sponge host as a symbiont. Menaquinone-7 was the sole isoprenoid quinone and antieiso-C15:0 (28.5%), iso-C16:0 (25.8%), C16:1 ω7c alcohol (15.0%), and iso-C15:0 (11.2%) were detected as the major fatty acids. Polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, and an unidentified lipid. The cell-wall peptidoglycan contained lysine, alanine, glutamate, and aspartate. Based on these analyses, strain 2205SS18-9T represents a novel species of the genus Chengkuizengella, for which the name Chengkuizengella axinellae sp. nov. is proposed. The type strain is 2205SS18-9T (= KACC 23238T = LMG 33063T).

Comparing amoxicillin and trimethoprim: Overall performance in combating Escherichia coli-causing urinary tract infection

Urinary Tract Infection (UTI) is one of the most prevalent bacterial infections in the world, and 80% of reported UTI cases are derived by gram negative bacteria Escherichia coli. Uropathogenic Escherichia coli is strongly adaptive and resilient against immune response, forming Intracellular Bacterial Communities (IBC) inside uroepithelium cells that constitute the urethra and the bladder. Their rapid absorption of cellular nutrients enables them to advance upward toward the kidney and cause inflammation. Hence, based on the perceived severity of UTI, multiple antibiotics are used to treat UPEC-causing UTI. This article provides a detailed review on the contemporary performance of amoxicillin and trimethoprim, both widely used to treat UPEC-causing UTI for decades. Amoxicillin is a penicillin-derivative that produces bactericidal by inhibiting transpeptidase to disrupt peptidoglycan synthesis, causing rapid-growing bacteria to lyse. It is a well-tolerated drug that can be used on pregnant patients. Resistant UPEC develop beta-lactamase to counter amoxicillin. Trimethoprim, on the other hand, is a dihydropyrimidine antibiotic that impedes the production of tetrahydrofolic acids, producing either bacteriostatic or bactericidal effects. Resistant UPEC transforms the shape of tetrahydrofolic acids-producing enzyme, dihydrofolic reductase, to resist trimethoprim. Although amoxicillin and trimethoprim are competitive inhibitors are effective against a variety of gram-positive and gram-negative species, trimethoprim, in statistical study, is proven to be more effective than amoxicillin in treating gram-negative UTI. Today, the wide-spread resistant strains of UPEC exists for both drugs. Thus, amoxicillin and trimethoprim are implemented mainly through combination therapies, amoxicillin/clavulanate and trimethoprim sulfamethoxazole, respectively. These combinations are more effective than the drugs to be used alone and are able to counter some resistant strains, but UPEC that are resistant to combinations also exists. Regardless, both amoxicillin and trimethoprim are still used as first-line antibiotics, while more powerful antibiotics are reserved for special multi-resistant superbugs.

SpoIIQ-dependent localization of SpoIIE contributes to septal stability and compartmentalization during the engulfment stage of Bacillus subtilis sporulation.

During spore development in bacteria, a polar septum separates two transcriptionally distinct cellular compartments, the mother cell and the forespore. The conserved serine phosphatase SpoIIE is known for its critical role in the formation of this septum and activation of compartment-specific transcription in the forespore. Signaling between the mother cell and forespore then leads to activation of mother cell transcription and a phagocytic-like process called engulfment, which involves dramatic remodeling of the septum and requires a balance between peptidoglycan synthesis and hydrolysis to ensure septal stability and compartmentalization. Using Bacillus subtilis, we identify an additional role for SpoIIE in maintaining septal stability and compartmentalization at the onset of engulfment. This role for SpoIIE is mediated by SpoIIQ, which anchors SpoIIE in the engulfing membrane. A SpoIIQ mutant (SpoIIQ Y28A) that fails to anchor SpoIIE, results in septal instability and miscompartmentalization during septal peptidoglycan hydrolysis, when other septal stabilization factors are absent. Our data support a model whereby SpoIIE and its interactions with the peptidoglycan synthetic machinery contribute to the stabilization of the asymmetric septum early in engulfment, thereby ensuring compartmentalization during spore development.IMPORTANCEBacterial sporulation is a complex process involving a vast array of proteins. Some of these proteins are absolutely critical and regulate key points in the developmental process. Once such protein is SpoIIE, known for its role in the formation of the polar septum, a hallmark of the early stages of sporulation, and activation of the first sporulation-specific sigma factor, σF, in the developing spore. Interestingly, SpoIIE has been shown to interact with SpoIIQ, an important σF-regulated protein that functions during the engulfment stage. However, the significance of this interaction has remained unclear. Here, we unveil the importance of the SpoIIQ-SpoIIE interaction and identify a role for SpoIIE in the stabilization of the polar septum and maintenance of compartmentalization at the onset of engulfment. In this way, we demonstrate that key sporulation proteins, like SpoIIQ and SpoIIE, function in multiple processes during spore development.

Lipoteichoic acid biosynthesis by Staphylococcus aureus is controlled by the MspA protein.

Staphylococcus aureus produces a plethora of virulence factors critical to its ability to establish an infection and cause disease. We have previously characterized a small membrane protein, MspA, which has pleiotropic effects on virulence and contributes to S. aureus pathogenicity in vivo. Here we report that mspA inactivation triggers overaccumulation of the essential cell wall component, lipoteichoic acid (LTA), which, in turn, decreases autolytic activity and leads to increased cell size due to a delay in cell separation. We show that MspA directly interacts with the enzymes involved in LTA biosynthesis (LtaA, LtaS, UgtP, and SpsB), interfering with their normal activities. MspA, in particular, interacts with the type I signal peptidase SpsB, limiting its cleavage of LtaS into its active form. These findings suggest that MspA contributes to maintaining a physiological level of LTA in the cell wall by interacting with and inhibiting the activity of SpsB, thereby uncovering a critical role for the MspA protein in regulating cell envelope biosynthesis and pathogenicity.IMPORTANCEThe S. aureus cell envelope, comprising the cytoplasmic membrane, a thick peptidoglycan layer, and the anionic polymers lipoteichoic acid and wall teichoic acids, is fundamental for bacterial growth and division, as well as being the main interface between the pathogen and the host. It has become increasingly apparent that the synthesis and turnover of cell envelope components also affect the virulence of S. aureus. In this study, we show that MspA, an effector of S. aureus virulence, contributes to the maintenance of normal levels of lipoteichoic acid in the cell wall, with implications on cell cycle and size. These findings further our understanding of the connections between envelope synthesis and pathogenicity and suggest that MspA represents a promising target for the development of future therapeutic strategies.

When the Host Encounters the Cell Wall and Vice Versa.

Peptidoglycan (PGN) and associated surface structures such as secondary polymers and capsules have a central role in the physiology of bacteria. The exoskeletal PGN heteropolymer is the major determinant of cell shape and allows bacteria to withstand cytoplasmic turgor pressure. Thus, its assembly, expansion, and remodeling during cell growth and division need to be highly regulated to avoid compromising cell survival. Similarly, regulation of the assembly impacts bacterial cell shape; distinct shapes enhance fitness in different ecological niches, such as the host. Because bacterial cell wall components, in particular PGN, are exposed to the environment and unique to bacteria, these have been coopted during evolution by eukaryotes to detect bacteria. Furthermore, the essential role of the cell wall in bacterial survival has made PGN an important signaling molecule in the dialog between host and microbes and a target of many host responses. Millions of years of coevolution have resulted in a pivotal role for PGN fragments in shaping host physiology and in establishing a long-lasting symbiosis between microbes and the host. Thus, perturbations of this dialog can lead to pathologies such as chronic inflammatory diseases. Similarly, pathogens have devised sophisticated strategies to manipulate the system to enhance their survival and growth.