Archives of Microbiology最新文献

The emergence of the “super fungus” Candida auris poses a significant threat to human health, given its multidrug resistance and high mortality rates. Therefore, developing a new antifungal strategy is necessary. Our previous research showed that Baicalein (BE), a key bioactive compound from the dried root of the perennial herb Scutellaria baicalensis Georgi, has strong fungistatic properties against C. auris. Nevertheless, the antifungal activity of BE against C. auris and its mechanism of action requires further investigation. In this study, we explored how BE affects this fungus using various techniques, including scanning electron microscopy (SEM), Annexin V-FITC apoptosis detection, CaspACE FITC-VAD-FMK In Situ Marker, reactive oxygen species (ROS) assay, singlet oxygen sensor green (SOSG) fluorescent probe, enhanced mitochondrial membrane potential (MMP) assay with JC-1, DAPI staining, TUNEL assay and reverse transcription–quantitative polymerase chain reaction (RT-qPCR). Our findings revealed that BE induced several apoptotic features, including phosphatidylserine (PS) externalization, metacaspase activation, nuclear condensation and DNA fragmentation. BE also increased intracellular ROS levels and altered mitochondrial functions. Additionally, transcriptomic analysis and RT-qPCR validation indicated that BE may induce apoptosis in C. auris by affecting ribosome-related pathways, suggesting that ribosomes could be new targets for antifungal agents, in addition to cell walls, membranes, and DNA. This study emphasizes the antifungal activity and mechanism of BE against C. auris, offering a promising treatment strategy for C. auris infection.

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Schematic representation of this study. Baicalein (BE) triggers apoptosis in Candida auris by affecting ribosome-related pathways. This action leads to several apoptotic characteristics, such as phosphatidylserine (PS) externalization, metacaspase activation, nuclear condensation, DNA fragmentation, increased levels of ROS and ¹O₂, and alterations in mitochondrial membrane potential (MMP)

Seaweed endophytes are a rich source of microbial diversity and bioactive compounds. This review provides a comprehensive analysis of the microbial diversity associated with seaweeds and their interaction between them. These diverse bacteria and fungi have distinct metabolic pathways, which result in the synthesis of bioactive compounds with potential applications in a variety of health fields. We examine many types of seaweed-associated microorganisms, their bioactive metabolites, and their potential role in cancer treatment using a comprehensive literature review. By incorporating recent findings, we hope to highlight the importance of seaweed endophytes as a prospective source of novel anticancer drugs and promote additional studies in this area. We also investigate the pharmacokinetic and pharmacodynamic profiles of these bioactive compounds because understanding their absorption, distribution, metabolism, excretion (ADMET), and toxicity profiles is critical for developing bioactive compounds with anticancer potential into effective cancer drugs. This knowledge ensures the safety and efficacy of proposed medications prior to clinical trials. This study not only provides promise for novel and more effective treatments for cancer with fewer side effects, but it also emphasizes the necessity of sustainable harvesting procedures and ethical considerations for protecting the delicate marine ecology during bioprospecting activities.

Staphylococcus aureus is a notorious pathogen predominantly involved in skin and soft tissue infections, exhibiting a distinct innate sex bias. This study explores the influence of testosterone on the virulence of S. aureus and elucidates its underlying mechanisms. Utilizing a skin abscess model in intact and castrated male mice, we assessed the effects of testosterone on S. aureus pathogenicity. Compared to controls, castrated mice showed significantly reduced abscess sizes and decreased bacterial loads, highlighting the role of testosterone in modulating the severity of S. aureus infections. In vitro experiments revealed that testosterone enhances the hemolytic activity, cytotoxicity, and oxidative stress resistance of S. aureus. Real-time quantitative PCR analysis showed a significant upregulation of the genes encoding α-hemolysin (hla) and phenol-soluble modulin (psmα). Importantly, testosterone treatment significantly enhanced the expression of the accessory gene regulator (Agr) quorum-sensing system components (agrC, agrA, agrB, agrD), while the SaeRS system (saeR, saeS, and sbi) exhibited only slight changes. Gene knockout experiments revealed that deletion of agrC, rather than saeRS and agrBD, abolishes the testosterone-induced enhancement of hemolysis and gene expression, underscoring the key role of AgrC. Molecular docking simulations indicated a direct interaction between testosterone and AgrC protein, with a strong binding affinity at the active site residue SER201. This study provides new insights into the mechanistic basis of how testosterone enhances the pathogenicity of S. aureus, potentially contributing to increased male susceptibility to S. aureus infections and offering a targeted approach for therapeutic interventions.

A global water crisis is emerging due to increasing levels of contaminated water and decreasing clean water supply on Earth. This study aims to address the removal of azo dye from wastewater to enable its reuse. Recently, utilizing microorganisms has been proven to be a practical choice for the remediation of azo dyes in wastewater. Hence, in this study, we employed a preformed biofilm of Pseudomonas aeruginosa on a solid support (called substrate) to degrade azo dyes. This process offers several advantages, such as stability, substrate portability, more biofilm production in less time, and efficient utilization of enzymes for remediation. From 50 ppm of initial Congo Red concentration, 75.74% decolorization was achieved within ten h using a preformed biofilm on a coverslip. A maximum of 52.27% decolorization was achieved using biofilm during its formation after 72 h of incubation. The Fourier-transform infrared (FTIR) spectroscopic analysis of Congo Red dye before and after remediation revealed a significant change in peak intensity, indicating dye degradation. Phytotoxicity studies performed by seed germination with Vigna radiata revealed that, after 5–7 days, almost 40% more seeds with longer root and shoot lengths were germinated in the presence of treated dye compared to the untreated one. This data indicated that the harmful Congo Red was successfully degraded to a non-toxic product by Pseudomonas aeruginosa biofilm grown on a glass substrate.

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Chlorine dioxide (ClO₂) is a strong oxidizing agent and an efficient disinfectant. Due to its broad-spectrum bactericidal properties, good inactivation effect on the vast majority of bacteria and pathogenic microorganisms, low resistance to drugs, and low generation of halogenated by-products, chlorine dioxide is widely used in fields such as water purification, food safety, medical and public health, and living environment. This review introduced the properties and application status of chlorine dioxide, compared the action mode, advantages and disadvantages of various disinfectants. The mechanism of chlorine dioxide inactivating bacteria, fungi and viruses were reviewed. The lethal target of chlorine dioxide to bacteria and fungi is to destroy the structure of cell membrane, change the permeability of cell membrane, and make intracellular substances flow out, leading to their death. The lethal targets for viruses are the destruction of viral protein capsids and the degradation of RNA fragments. The purpose of this review is to provide more scientific guidance for the application of chlorine dioxide disinfectants.

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Antimicrobial resistance (AMR) is global health concern escalating rapidly in both clinical settings and environment. The effluent from pharmaceuticals and hospitals may contain diverse antibiotics, exerting selective pressure to develop AMR. To study the aquatic prevalence of drug-resistant staphylococci, sampling was done from river Yamuna (3 sites) and wastewater (7 sites) near pharmaceutical industries in Delhi-NCR, India. 59.25% (224/378) were considered presumptive staphylococci while, methicillin resistance was noted in 25% (56/224) isolates. Further, 23 methicillin-resistant coagulase negative staphylococci (MR-CoNS) of 8 different species were identified via 16S rRNA gene sequencing. Multidrug resistance (MDR) was noted in 60.87% (14/23) isolates. PCR based detection of antibiotic resistance genes revealed the number of isolates containing mecA (7/23), blaZ (6/23), msrA (10/23), aac(6′)aph (2”) (2/23), aph(3′)-IIIa (2/23), ant(4′)-Ia (1/23), dfrG (4/23), dfrA(drfS1) (3/23), tetK (1/23) and tetM (1/23). The current research highlights the concerning prevalence of MDR-CoNS in aquatic environment in Delhi.

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Increasing awareness regarding health promotion and disease prevention has driven inclusion of fermented foods and beverages in the daily diet. These are the enormous sources of beneficial microbes, probiotics. This study aims to isolate yeast strains having probiotic potential and effectivity against colitis. Initially, ninety-two yeast strains were isolated from Haria, an ethnic fermented beverage of West Bengal, India. Primary screening was done by their acid (pH 4) and bile salt (0.3%) tolerance ability. Four potent isolates were selected and found effective against Entamoeba histolytica, as this human pathogen is responsible to cause colitis. They were identified as Saccharomyces cerevisiae. They showed luxurious growth even at 37 ^oC, tolerance up to 5% of NaCl, resistance to gastric juice and high bile salt (2.0%) and oro-gastrointestinal transit tolerance. They exhibited good auto-aggregation and co-aggregation ability and strong hydrophobicity. Finally, heat map and principal component analysis revealed that strain Y-89 was the best candidate. It was further characterised and found to have significant protective effects against DSS-induced colitis in experimental mice model. It includes improvement in colon length, body weight and organ indices; reduction in disease activity index; reduction in cholesterol, LDL, SGPT, SGOT, urea and creatinine levels; improvement in HDL, ALP, total protein and albumin levels; decrease in coliform count and restoration of tissue damage. This study demonstrates that the S. cerevisiae strain Y-89 possesses remarkable probiotic traits and can be used as a potential bio-therapeutic candidate for the prevention of colitis.

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Cello-oligosaccharides (COS) become a new type of functional oligosaccharides. COS transglycosylation reactions were studied to enhance COS yield production. Seeking the ability of the free form of Fusarium solani β-glucosidase (FBgl1) to synthesize COS under low substrate concentrations, we found out that this biocatalyst initiates this reaction with only 1 g/L of cellobiose, giving rise to the formation of cellotriose. Cellotriose and cellopentaose were detected in biphasic conditions with an immobilized FBgl1 and when increased to 50 g/L of cellobiose as a starter concentration. After the biocatalyst recycling process, the trans-glycosylation yield of COS was maintained after 5 cycles, and the COS concentration was 6.70 ± 0.35 g/L. The crude COS contained 20.15 ± 0.25 g/L glucose, 23.15 ± 0.22 g/L non-reacting substrate cellobiose, 5.25 ± 0.53 g/L, cellotriose and 1.49 ± 0.32 g/L cellopentaose. A bioprocess was developed for cellotriose enrichment, using whole Bacillus velezensis cells as a microbial purification tool. This bacteria consumed glucose, unreacted cellobiose, and cellopentaose while preserving cellotriose in the fermented medium. This study provides an excellent enzyme candidate for industrial COS production and is also the first study on the single-step COS enrichment process.

Escherichia coli can colonise the urogenital tract of individuals without causing symptoms of infection, in a condition referred to as asymptomatic bacteriuria (ABU). ABU isolates can protect the host against symptomatic urinary tract infections (UTIs) by bacterial interference against uropathogenic E. coli (UPEC). The aim of this study was to investigate the genotypic and phenotypic characteristics of five ABU isolates from midstream urine samples of adults. Comparative genomic and phenotypic analysis was conducted including an antibiotic resistance profile, pangenome analysis, and a putative virulence profile. Based on the genome analysis, the isolates consisted of one from phylogroup A, three from phylogroup B2, and one from phylogroup D. Two of the isolates, PUTS 58 and SK-106-1, were noted for their lack of antibiotic resistance and virulence genes compared to the prototypic ABU strain E. coli 83,972. This study provides insights into the genotypic and phenotypic profiles of uncharacterised ABU isolates, and how relevant fitness and virulence traits can impact their potential suitability for therapeutic bacterial interference.

Bacteria threaten human and animal health, and standard antibiotics no longer effective. Antibiotic-resistant microorganisms can make infection treatment challenging and perhaps fail. Investigating the attributes of cyclotide, a peptide with promising antibacterial properties that holds great potential in the field of antibiotic research. The structure of these cyclic peptides involves six conserved cysteine residues that form three disulfide bonds, resulting in a cyclic cystine knot (CCK). This feature guarantees their durability when exposed to changes in temperature, chemicals, and enzymatic degradation. The two cyclotides, cycloviolacin O17 and mra30, were obtained from Viola dalatensis Gadnep through a series of techniques including the use of a 50% acetonitrile/49% miliQ water/1% formic acid solution for extraction, ammonium salt precipitation, RP-HPLC purification and sequence identification by LC-MS/MS. These cyclotides exhibit antibacterial effects on specific strains of bacteria like Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa at a concentration of 0.2 mg/mL, leading to inhibition zones ranging from 10 to 14 mm. In addition, the disulfide bonds play a crucial role in the antibacterial function of cyclotides. Disrupting the disulfide bonds through ankylation reaction results in the loss of antibacterial properties in the cyclotides (cyO17 and mra30). The minimum inhibitory concentration (MIC) values of mra30 and cyO17 are significantly low, ranging from 0.1 to 0.6 µM. These values are approximately three times lower than the MIC values observed in salt precipitation samples.