Archives of Microbiology最新文献

The research investigated the biochemical properties of spoilage bacteria Pseudomonas fragi (P. fragi) in grouper (Epinephelus lanceolatus) during cold storage. The proteolytic activity and the spoilage-related metabolic pathway were characterized by whole genome sequencing. The results revealed optimal protease activity at pH 7.0 and 40 °C, with significant inhibition observed in the presence of protease inhibitors, organic solvents, and metal ions. The kinetic analysis demonstrated strong substrate affinity, while the thermodynamic parameters indicated excellent thermal stability. Freshness index evaluations confirmed the potential of fish protein degradation of P. fragi. The whole genome sequencing has made gene-level protease analysis a crucial approach for investigating protease metabolism. Genes associated with protein degradation and spoilage pathways were identified. The results revealed that both P. fragi V11 and SS strains contain 36 protease-encoding genes, with metalloprotease and serine protease representing the predominant proteases in P. fragi. These identified genes functioned in regulating amine, sulfur and amino acid metabolism. Whole genome sequencing may offer valuable insights into protease mechanisms and protein degradation processes.

Yeast is a core microorganism long used in food industry processes such as brewing and baking. This study aimed to investigate the immunomodulatory potential of mannatide (MTE) derived from brewer’s yeast in both cyclophosphamide (CTX)-induced immunosuppressed and untreated mice. Results showed that MTE administration alleviated body weight loss, restored organ morphology, and increased immune cytokines (TNF-α and IFN-γ) in immunosuppressed mice. In addition, MTE up-regulated tight junction proteins (Occludin, E-cadherin , and ZO-1) and resolved gut microbial dysbiosis by enriching beneficial bacteria. In untreated mice, MTE significantly increased beneficial bacteria without adverse effects. These findings suggest that MTE exerts immunoenhancing effects in both immunosuppressed and untreated mice by modulating immune parameters and gut microbiota. In conclusion, MTE represents a dietary supplement with immunomodulatory and prebiotic potential, providing a theoretical basis for its application in human health and nutrition.

The development of microbial bioproducts requires understanding the stability and viability of cells during storage. Accordingly, this study evaluated the viability of capsules containing different strains of Trichoderma spp. isolated from native plants of the Piauí Cerrado, using an integrated approach combining microencapsulation and computational modeling. Capsules were produced by ionic gelation in a sodium alginate matrix, and fungal viability was monitored by plating and conidial counting over 60 days of storage. The resulting data were used to train a Multilayer Perceptron (MLP) Artificial Neural Network, structured with an ELU activation function, L2 regularization, and dropout to prevent overfitting. The model was also able to generate projections beyond the experimental period; however, these estimates are strictly exploratory in nature and serve only as a proof of concept for the application of MLPs to describe potential trends beyond the 60 days observed. Within the experimental window, strains UFPI07, UFPI10, UFPI11, and UFPI16 maintained populations above 7 log CFU mL^− 1, indicating greater relative stability, whereas UFPI06 and UFPI18 exhibited a more pronounced decline. The combination of encapsulation and machine learning demonstrates potential as a tool to support preliminary estimates of temporal behavior, optimize formulations, and reduce experimental costs, representing an exploratory methodological advance for predictive microbiology and bioproduct development.

Quorum sensing (QS) is a fundamental bacterial communication mechanism that promotes population-dependent behaviors including biofilm formation, virulence, and sporulation via signaling molecules called autoinducers. This review provides a comprehensive overview of QS and quorum sensing–mediated cross-talk in Gram-negative bacteria using N-acyl-homoserine lactones (AHLs), Gram-positive bacteria employing oligopeptides, and the universal autoinducer-2 (AI-2) system. Advances in synthetic biology and engineered QS circuits have improved understanding and control of microbial communication. The review highlights quorum quenching (QQ) and diverse classes of quorum sensing inhibitors (QSIs)-natural, synthetic, antibody-based, enzymatic, CRISPR-mediated, and those currently in clinical trials-focusing on their potential to interfere with signaling pathways and attenuate virulence. The interplay between QS, antimicrobial resistance (AMR), and QSIs is examined, emphasizing their capability to suppress pathogenicity without inducing resistance. Recent emerging approaches for QS regulation have also been mentioned. The applications of QS-targeted strategies in healthcare, agriculture, aquaculture, food industry, and medical device biofilm management are discussed, underscoring the translational promise of QSIs as sustainable, resistance-free tools for effective antimicrobial control.

Severe aphid infestations drive unsustainable pesticide use, necessitating deeper understanding of aphid-plant-microbe interactions. To control those pests like aphids, which may cause severe infestations on vegetables and field crops, we need to understand how they maintain the relationship with the host plant. So, these studies compiled interesting characteristics of microbial involvements in plant-aphid interaction and the specific roles of bacterial communities, and how those impact the actual interactions between aphids and their plant hosts. This includes aphid-sympathetic (obligate and facultative) and plant-associated bacteria (that may either be in the rhizosphere or phyllosphere or endophytic) that can change or influence both plant defense response, as well as aphid physiology and ecology in general. We outlined some functional traits of bacteria, focusing on enzymatic and metabolic activities that reveal their ecological and protective roles. The review emphasizes key microbial traits such as catalase, protease, lipase, siderophore production, and phosphate solubilization, highlighting their functions within the plant-aphid-microbe triangle. studies aim to classify and describe two broad bacterial groups associated with aphids and host plants, evaluate their functional roles in mediating host resistance or enhancing aphid virulence, and the interaction causes. Further case studies and recent findings illustrating these tripartite interactions, and discuss how microbial traits can be leveraged for sustainable pest management (SPM) and crop improvement.

This study investigates the spatiotemporal distribution, diversity, and biocontrol potential of culturable endophytic fungi in the healthy roots of cultivated and wild Astragalus mongholicus (CA and WA), aiming to develop a microbiome-driven strategy for sustainable root rot management. A total of 304 endophytic fungal strains were isolated from roots of CA and WA, with 61 morphologically distinct representative strains identified via ITS sequencing. These strains belonged predominantly to Ascomycota (98.36%) and included 21 genera, with Fusarium (43.28%), Paraphoma (25.25%), and Alternaria (12.46%) as dominant genera. WA exhibited higher fungal diversity and evenness than CA, with community composition varying significantly by host age and cultivation status. Among the isolates, 177 strains (53 genera) showed antagonistic activity (≥ 30% inhibition rate) against root rot pathogens (F. acuminatum, F. solani, and F. oxysporum). Notably, Penicillium chrysogenum CA4-3 exhibited 78.96% inhibition against F. solani, while Paraphoma radicina CA3-15 displayed 70.23% inhibition against F. oxysporum. Bioactive strains were concentrated in 2 to 4-year-old CA roots, with Fusarium, Paraphoma, and Alternaria being the primary contributors. Mechanistic studies revealed that these fungi inhibited pathogens via secreted metabolites (causing mycelial deformation) or niche competition. The composition of endophytic fungi in A. mongholicus roots is dynamic and influenced by host development and cultivation practices. The antifungal active strain P. chrysogenum CA4-3 and P. radicina CA3-15 may possess potential value in controlling pathogenic fungi.

Bacillus cereus is a significant foodborne pathogen due to its toxin production and resilient spores and biofilms that survive conventional sterilization methods. Bacteriophages and endolysins have shown considerable potential for controlling B. cereus in foods and on food-contact surfaces. Despite this, no recent review has comprehensively addressed phages as a control strategy against B. cereus. This review summarizes recent research on the application of B. cereus phages and endolysins in various food matrices and surfaces. Phage DZ1 reduced B. cereus counts by 4.21 log₁₀ CFU/mL in milk after 6 h, with bacterial counts remaining undetectable for up to 72 h, while PlyB13S endolysin at 0.8 µM removed over 60% of B. cereus biofilms on polystyrene surfaces. The review also highlights strategies combining phages with germinants to target spores, as well as phage cocktails, engineering, and encapsulation approaches to overcome limitations such as a narrow host range and environmental instability.

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Antibiotic resistance has intensified the need for alternatives, and probiotics offer a natural strategy by enhancing host immunity. The present study investigated the probiotic potential of Bacillus sp. 475B, a strain isolated from a high-temperature hydrothermal vent. In vitro assessments included its safety profile (cytotoxicity, hemolytic activity, and antibiotic susceptibility), tolerance to gastrointestinal and physicochemical stressors, antimicrobial activity, and gut adherence capacity. Additionally, the immunomodulatory effects of Bacillus sp. 475B were evaluated in mice supplemented daily (1 × 10⁸ CFU). Splenocytes were isolated on days 5 and 10, challenged ex vivo with Escherichia coli, and analyzed for immunological assays. Serum and fecal IgA and IgG levels were also quantified. Bacillus sp. 475B was non-cytotoxic, non-hemolytic, and susceptible to most tested antibiotics. The strain tolerated low pH, bile salts, high salinity, and high temperatures, as well as the capacity to adhere to the jejunum of healthy mice determined by fluorescence microscopy. Supernatants from cultures at 30 and 50 °C inhibited the growth of methicillin-resistant Staphylococcus aureus (MRSA). In vivo enhanced immune responses as indicated by increased nitric oxide production and myeloperoxidase activity. Antibody levels were not affected by supplementation with the strain. These findings highlight the potential of Bacillus sp. 475B is a robust and functional probiotic candidate for future applications in health and biotechnology.

The mutual association formed between the gut flora and the biological host is pivotal, mainly for drug action. Various examination has spotlighted the potential consequences of the gut microbiome on drug efficacy, revealing its role in controlling metabolism in the body. Furthermore, reciprocal engagement has been examined to investigate how pharmaceutical agents influence the composition of the gut microbiome. This paper emphasizes the intricate relationship between pharmacology and environmental microbiology, directing the extensive significance of pharmaceutical agents on health by controlling the gut microbial consortium. One main highlight of this review is to determine the differences observed in populace as a result of drugs, which is a crucial component in boosting personalized treatment approaches and intensifying therapeutic findings. Apart from their function in drug metabolization, the gut microbiota is disclosed as a source of metabolic products that can alter drug action. These microbially-derived metabolites could notably effect drug results and changes the body’s physical mechanisms. The investigation suggests utilizing metabolomics to disclose the complications of gut microbiota–drug interactions. Several latest analytical strategies provide an effective tool for deciphering the complicated association among microbiome-generated fragments and pharmaceutical products, providing detailed understanding into this interesting connection.

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Agro-industrial wastes contain lignocellulose, of which, the hemicellulosic fraction can be utilized for the production of value-added products such as xylitol, leading to the generation of a cost-effective and sustainable bioprocess. Biomass pretreatment is necessary for efficient enzymatic hydrolysis, with alkaline pretreatment enhancing the bioavailability of fermentable sugars such as xylose from the hemicellulosic component of lignocellulosic biomass. In the current study, a xylanolytic Aspergillus terreus strain was exposed to the chemical mutagen EMS in an attempt to enhance the xylanase enzyme production, reaching 12.83 UmL⁻¹. Subsequently, upon optimization of process and parameters, at a pH of 6.5, a reaction temperature of 60 °C, with the presence of 20 mM Zn²⁺ metal ions, the xylanase activity further increased to 16.11 UmL⁻¹. Upon saccharification of sugarcane bagasse, 0.21 gg⁻¹ xylose yield was obtained, and Yarrowia lipolytica strain was used for the biotransformation of xylose to xylitol using the bagasse hydrolysate as nutrient source. A titer of 10.27 gL⁻¹ was achieved utilizing solely sugarcane bagasse derived xylose as a nutrient source, thereby facilitating the application of the Y. lipolytica strain for the bioremediation of lignocellulosic biomass and the production of value-added products.

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