Archives of Microbiology最新文献

Outer membrane vesicles derived from Pseudomonas aeruginosa (PA-OMVs) play a crucial role in bacterial pathogenesis, mediating immune modulation and inflammation. Autophagy, a process that degrades damaged organelles, and pyroptosis, a form of programmed cell death, both regulate immune responses and contribute to infection defense. However, the relationship between PA-OMVs, autophagy, and pyroptosis remains insufficiently explored, particularly regarding their regulatory mechanisms. This study investigates how PA-OMVs influence cellular autophagy and pyroptosis, with the aim of identifying potential therapeutic strategies for infectious diseases. Bulk RNA sequencing and bioinformatics analysis were conducted on cells treated with PA-OMVs. Autophagy inhibitors, chloroquine (CQ) and 3-methyladenine (3-MA), were used to explore their effects on pyroptosis, with RT-PCR and ELISA applied to assess pyroptosis levels. The results revealed a complex interplay between autophagy and pyroptosis, with PA-OMVs modulating key immune and inflammatory pathways. Autophagy inhibition decreased the expression of pyroptosis markers, suggesting a regulatory role. These findings highlight the potential of targeting the autophagy-pyroptosis axis for new infection control strategies and vaccine development.

The LasR quorum sensing system regulates the virulence factors of Pseudomonas aeruginosa, a multi-drug resistant pathogen. Mangiferin and related compounds have been found to modulate this system as determined by in silico and in vitro experimental procedures. ZINCPharmer was used to compile a library of over 1000 metabolites that were screened to the top five based on shared pharmacophores and drug-like properties with mangiferin. Molecular docking and molecular dynamics simulation (140 ns) showed that ZINC E (− 55.64 ± 2.93 kcal/mol) and ZINC D (− 54.51 ± 2.82 kcal/mol) had significantly lower binding free energy compared to mangiferin-LasR (− 42.24 ± 3.94 kcal/mol) and the reference standard (azithromycin-LasR (− 40.01 ± 6.15 kcal/mol). ZINC D (95.16%) competed favorably with mangiferin (95.77%) as potential QS modulators at sub-minimum inhibitory concentrations relative to ZINC E (85.07%) and azithromycin (85.79%). These observations suggest mangiferin and related lead compounds as potential drug candidates for P. aeruginosa infection management.

Heterologous expression of the putative 1,3,6,8-tetrahydroxynaphthalene synthase gene ChPKS from Colletotrichum higginsianum in Aspergillus nidulans led to the formation of at least eight new compounds. LC-MS analysis proved them as coupling products of 1,3,6,8-tetrahydroxynaphthalene with an intermediate of the cichorine biosynthetic pathway. Comprehensive NMR analysis confirmed the structures of the two predominant products higginidulans A and B. Deletion of the backbone gene of the cichorine pathway in host strain Aspergillus nidulans abolished the formation of higginidulans. Heterologous expression of ChPKS in the alternative Penicillium crustosum expression host resulted in the formation of the expected product 1,3,6,8-tetrahydroxynaphthalene, which was confirmed by acetylation and structural elucidation. This study provides an additional example of unexpected natural product formation by crosstalk of biosynthetic pathways derived from different species. Moreover, it highlights the importance of using alternative host systems for gene expression.

Composting converts organic agricultural wastes into value-added products, yet the presence of significant non-biodegradable lignocelluloses hinders its efficiency. The introduction of various exogenous microbial agents has been shown to effectively addresses this challenge. In this context, basing on the microbial enzymatic mechanism for lignocellulose degradation, this paper synthesizes the latest research advancements and practical applications of exogenous microbial agents in agricultural waste composting. Given that the effectiveness of lignocellulose degradation is highly dependent on the waste’s inherent characteristics, it is crucial to carefully consider the composition of fungi and bacteria, the dosage of microbial agents, and the composting process operation, tailored to the specific type of agricultural waste. Moreover, the combination of additives with exogenous microbial agents can further enhance the degradation of lignocelluloses and the humification of organic matters. Furthermore, insights into the future research and application trends of exogenous microbial agents in agricultural waste composting was prospected.

Graphical abstract

Trimetallic nanoparticles (TMNPs) have emerged as a pivotal area of research due to their unique properties and diverse applications across medicine, agriculture, and environmental sciences. This review provides several novel contributions that distinguish it from existing literature on trimetallic nanoparticles (TMNPs). Firstly, it offers a focused exploration of TMNPs, specifically addressing their unique properties and applications, which have been less examined compared to other multimetallic nanoparticles. This targeted analysis fills a significant gap in current research. Secondly, the review emphasizes innovative biosynthesis methods utilizing microorganisms and plant extracts, positioning these green synthesis approaches as environmentally friendly alternatives to traditional chemical methods. This focus aligns with the increasing demand for sustainable practices in nanotechnology. Furthermore, the review integrates discussions on both medical and agricultural applications of TMNPs, highlighting their multifunctional potential across diverse fields. This comprehensive perspective enhances our understanding of how TMNPs can address various challenges. Additionally, the review explores the synergistic effects among the different metals in TMNPs, providing insights into how these interactions can be harnessed to optimize their properties for specific applications. Such discussions are often overlooked in existing studies. Moreover, this review identifies critical research gaps and challenges within the field, outlining future directions that encourage further investigation and innovation in TMNP development. By doing so, it proactively contributes to advancing the field. Finally, the review advocates for interdisciplinary collaboration among material scientists, biologists, and environmental scientists, emphasizing the importance of diverse expertise in enhancing the research and application of TMNPs.

MWCNT is being explored in various sectors like medical healthcare, electronics, aerospace, defence research, and many more leading to the continuous generation of waste discharged into water sources. Once introduced into the environment it may adversely affect flora and fauna. It is high time MWCNT should be recovered, treated, and degraded from wastewater. Bio-degradation is one of the popular sustainable techniques for the remediation of hazardous contaminants. This work evaluated indigenous microbes Bacillus nitratireducens SW_NMI_TSB1, Comamonas denitrificans SW_NMI_TSB2, and Lysinibacillus fusiformis SW_NMI_TSB3 isolated from the nanomaterial manufacturing industry from India for their competence in degrading MWCNT. The microbes in this study showed survivability in the nutrient medium devoid of carbon but containing MWCNT (100 and 400 mg/L). The bacterial strain exhibited proliferation for up to 50 days. Degradation of MWCNT can be observed through TEM images which displayed the distorted morphology, XRD, and RAMAN spectroscopy revealed that treated MWCNT exhibit a loss of structural integrity. SEM images and colony forming unit (CFU) counts show a good survival rate of the three isolates independently and in the consortium. LCMS detected intermediates generated during MWCNT degradation. The microbes isolated in this study can survive in the presence of MWCNT and exhibit degradation of MWCNT. The three isolates could biodegrade the MWCNT however their consortium showed the highest potential. The prospects of this study lie in utilizing the consortium of these strains for large-scale MWCNT degradation, improving water treatment systems, and advancing sustainable nanomaterial management practices.

Graphical Abstract

Lyophyllum decastes is a type of edible and medicinal mushroom with high nutritional value. However, it can be infected by fungi during the fruiting process, which impairs the development of the industry. In this study, one pathogenic fungus was isolated from the diseased fruiting bodies of L. decastes. Morphological and molecular identification clarified that the causal agent of the disease was Cladobotryum mycophilum. Koch’s postulates showed that C. mycophilum could infect L. decastes, and seriously affect mushroom yields. The biological properties of C. mycophilum were investigated. The data showed that the most suitable temperature for the growth of C. mycophilum was 25 °C with a mean growth rate of 21.45 mm d^− 1 on PDA. C. mycophilum was better suited to growing in neutral or slightly acidic environments. The suitable carbon source and nitrogen source for C. mycophilum growth were lactose and peptone or yeast extract respectively. The IC₅₀s (Half maximal inhibitory concentration) values of carbendazim and prochloraz for inhibiting C. mycophilum are respectively 1.244 µg.mL^− 1 and 3.323 µg.mL^− 1. 10 µg.mL^− 1 carbendazim can effectively control C. mycophilum during the L. decastes fruiting process. The results of this study can provide knowledge for the control of cobweb disease during the L. decastes fruiting process.

Bacteriophages produce endolysins at the end of the lytic cycle, which are crucial for lysing the host cells and releasing virion progeny. This lytic feature allows endolysins to act as effective antimicrobial alternatives when applied exogenously. Staphylococcal endolysins typically possess a modular structure with one or two enzymatically active N-terminal domains (EADs) and a C-terminal cell wall binding domain (CBD). The EADs degrade the peptidoglycan layer, leading to bacterial lysis, while the CBD binds to the specific host cell wall, and therefore, influences specificity of the endolysin. This study aimed to alter and characterize the host specificity of the CBD by exploring the impact of amino acid modifications within the CBD of a staphylococcal endolysin, Endo88. Endo88 was able to lyse Staphylococcus spp. and Enterococcus faecalis. However, despite attempts to mutate amino acids hypothesized for binding with cell wall components, the host-range was not affected but the lytic activity was severely reduced instead, although no alterations were performed on the EADs (Cysteine, histidine-dependent aminohydrolases/peptidases domain and Amidase domain). Further investigations of the CBD alone (Src homology3 domain, SH3) without the EADs suggested that binding and lytic activity may not be correlated in some cases since Endo88 and its mutants could lyse Staphylococcus epidermidis well but no binding activity was observed in the flow cytometry analysis. Molecular docking was used to gain insights on the observations for the binding and lytic activity which may help future strategies in designing enhanced engineered endolysins.

Environmental factors play a crucial role in bacterial virulence. During transmission, in a non-host environment bacteria are exposed to various environmental stress which could alter bacterial physiology and virulence. N. meningitidis is transmitted from person to person through direct contact. However, the role of environmental desiccation in the virulence of bacterial pathogens is not clearly understood. Therefore, the effect of environmental desiccation on survival, transmission, and virulence needs further investigation. We demonstrate that N. meningitidis was sensitive to desiccation stress. The viable counts reduced significantly (p < 0.05) after desiccation. It was found that desiccation induces a viable but non-culturable state (VBNC) in N. meningitidis. We considered cells to be in VBNC when no viable counts were obtained on growth media and live cells were detected after live-dead staining. After resuscitation, N. meningitidis retained virulence characteristics which indicate that it can transit between the host in VBNC state. Furthermore, the relative expression of capsule increased significantly after 12 and 24 h of desiccation. The observations indicate that the environmental desiccation might induce capsule biosynthesis in N. meningitidis, leading to enhanced virulence and survival in macrophages.

Graphical Abstract

Astaxanthin (ASX), “king of carotenoids”, is a xanthophyll carotenoid that is characterized by a distinct reddish-orange hue, procured from diverse sources including plants, microalgae, fungi, yeast, and lichens. It exhibits potent antioxidant and anti-ageing properties and has been demonstrated to mitigate ultraviolet-induced cellular and DNA damage, enhance immune system function, and improve cardiovascular diseases. Despite its broad utilization across nutraceutical, cosmetic, aquaculture, and pharmaceutical sectors, the large-scale production and application of ASX are constrained by the limited availability of natural sources, low production yields and stringent production requirements. This review provides a comprehensive analysis of ASX applications, emphasizing its dual roles in cosmetic and nutraceutical fields. It integrates insights into the qualitative differences of ASX from various natural sources and assesses biosynthetic pathways across organisms. Advanced biotechnological strategies for industrial-scale production are explored alongside innovative delivery systems, such as emulsions, films, microcapsules, nanoliposomes, and nanoparticles, designed to enhance ASX’s bioavailability and functional efficacy. By unifying perspectives on its nutraceutical and cosmetic applications, this review highlights the challenges and advancements in formulation and commercialization. Prospective research directions for optimizing ASX’s production and applications are also discussed, providing a roadmap for its future development.