Archives of Microbiology最新文献

Feed-based bivalent vaccine (FBBV) containing killed whole organism (KWO) of Streptococcus agalactiae and Aeromonas hydrophila with 10% palm oil was previously proved to improve red hybrid tilapia’s (Oreochromis sp.) immunity against streptococcosis and Aeromonas infections. This study characterized the FBBV’s stability following the preparatory process and storage. The FBBV was prepared, and the KWO’s stability was determined microscopically and molecularly. The efficacy of FBBV stored at room temperature (25 ± 2 °C) for 0, 30 and 60 days was investigated in red hybrid tilapia. The results indicated the addition of palm oil was not affecting the KWO’s structure and helping in the FBBV’s pelletization. In 1 g of FBBV contained 1.5 × 10⁹ CFU/g of S. agalactiae and 4.9 × 10⁹ CFU/g of A. hydrophila, respectively, even after 60 days of storage at room temperature. The KWO’s structure in FBBV was not affected following in vitro acidic tolerance analysis, as noted from light and electron microscopies. The FBBV’s carbohydrate, energy, moisture, total protein and total ash contents remained stable at 95% after 60 days of storage at room temperature, while the KWO’s concentration was slightly reduced to 83.3% for S. agalactiae (1.25 × 10⁹ CFU/g) and 80.6% for A. hydrophila (3.85 × 10⁹ CFU/g), respectively. Fish vaccinated with FBBV that was stored for 0, 30 and 60 days did not show any significant differences (p ≥ 0.05) in the relative percent survival when challenged with pathogenic Streptococcus spp. and Aeromonas spp. These findings suggested that the FBBV is a stable vaccine, which underscores its potential application as aquatic vaccines in aquaculture.

Quercetin is a natural flavonoid with antioxidant, anti-inflammatory, and antibacterial properties. This work aimed to formulate quercetin-cyclodextrin microcapsules (QT-β-CD) while examining their photodynamic antibacterial effects and underlying mechanisms in detail. Characterization of the QT-β-CD was conducted using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The bacteriostatic effects of UV-A irradiation on Escherichia coli O157:H7 (E. coli O157:H7) were investigated. The photodynamic impact of QT-β-CD was assessed by analyzing hydrogen peroxide (H₂O₂) production. The antimicrobial activity was further elucidated through examinations of cell membrane integrity, protein damage, changes in cellular motility, biofilm formation, and extracellular polysaccharide reduction. The effect of QT-β-CD on LuxS and motA gene expression in E. coli O157:H7 was investigated by RT-qPCR. The findings demonstrated that QT-β-CD exhibited potent photodynamic properties and functioned as an efficient photosensitizer, causing substantial damage to E. coli O157:H7 cells. These results underscore the potential of quercetin as an antimicrobial agent for food preservation.

Streptomyces has long been considered as key sources for natural compounds discovery in medicine and agriculture. These compounds have been demonstrated to possess different biological activities, including antibiotic, antifungal, anticancer, and antiviral effects. As a result, new pharmaceuticals and antibiotics have been developed. Nevertheless, there have been only a few novel discoveries of bioactive compounds in the past decades from Streptomyces in natural habitats. There is, therefore, now a renewed search for new Streptomyces species having the potential to produce many compounds from one strain in lesser explored natural habitats that may be helpful in fighting diseases. Consequently, modern genome mining approaches are imperative for discovering structurally novel natural compounds with therapeutic applications from untapped sources. In light of these facts, endophytic Streptomyces from plants may offer new avenues for the discovery of bioactive compounds with distinctive chemical properties and activities. In the present review, we present the progress made in isolating natural compounds from endophytic Streptomyces originating from plants which have remarkable antimicrobial, cytotoxic, and antifungal properties. A different of distinct structural classes of compounds were reported from endophytic Streptomyces, such as indolosequiterpene, macrolides, flavones, peptides, naphthoquinones, and terpenoids. Further, we discussed modern genomics progress in finding biosynthetic gene clusters (BGCs) encoding compounds. Overall, this review might provide valuable insights into the potential for novel drug discovery from untapped endophytic Streptomyces in the future.

Plastic waste accumulation has lately been identified as the leading and pervasive environmental concern, harming all living beings, natural habitats, and the global market. Given this issue, developing ecologically friendly solutions, such as biodegradation instead of standard disposal, is critical. To effectively address and develop better strategies, it is critical to understand the inter-relationship between microorganisms and plastic, the role of genes and enzymes involved in this process. However, the complex nature of microbial communities and the diverse mechanisms involved in plastic biodegradation have hindered the development of efficient plastic waste degradation strategies. Omics-driven approaches, encompassing genomics, transcriptomics and proteomics have revolutionized our understanding of microbial ecology and biotechnology. Therefore, this review explores the application of omics technologies in plastic degradation studies and discusses the key findings, challenges, and future prospects of omics-based approaches in identifying novel plastic-degrading microorganisms, enzymes, and metabolic pathways. The integration of omics technologies with advanced molecular technologies such as the recombinant DNA technology and synthetic biology would guide in the optimization of microbial consortia and engineering the microbial systems for enhanced plastic biodegradation under various environmental conditions.

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During the process of fruit wine production, yeast plays a crucial role in influencing the taste, flavor, and overall quality of the wine. This study aims to enhance the flavor and quality of loquat wine by isolating strains of Pichia kudriavzevii (P. kudriavzevii) with desirable winemaking characteristics from loquat fruit fermentation broth. A total of 12 strains of P. kudriavzevii were isolated and subjected to morphological and molecular biological identification. Their fermentation performance, ethanol production, ester production, hydrogen sulfide production, killer activity, and tolerance were evaluated. The results revealed that strains Q-2, Q-9, Q-10, Q-12, Q-20, and Q-42 exhibited robust growth and strong tolerance under conditions of 40 °C temperature, 12% ethanol concentration, 350 g/L glucose concentration, and pH 2.8. Strain Q-42 demonstrated the strongest gas production capacity, killer activity, and good ester and ethanol production. As a highly active fermentation strain with excellent wine making characteristics, P. kudriavzevii Q-42 provides a valuable yeast resource for the industrial production of loquat wine and offers technical support for improving the overall quality of loquat wine.

Previous research on Magnetospirillum gryphiswaldense MSR-1 found that MSR-1 has a good denitrification nitrogen removal ability and specific application prospects in the sewage biological nitrogen removal field. Therefore, this study selected the essential denitrification gene NapA in MSR-1-wt for overexpression, and the overexpressed MSR-1-NapA was successfully constructed. Q-PCR amplification experiment and AGAR gel electrophoresis experiment proved that the relative transcription level of the NapA gene was increased by more than four times, and the denitrification ability of MSR-1-wt and MSR-1-NapA was further determined by enzyme activity experiment, denitrification experiment, and flow cytometry. The results showed that overexpression of the NapA gene increased nitrate reductase activity in MSR-1-NapA by more than four times. In the solution with a nitrate concentration of 118.33 ± 3.23 mgN/L, the denitrification efficiency of MSR-1-NapA was superior to that of MSR-1-wt, significantly enhancing both the denitrification and nitrogen removal capacities of MSR-1. This indicates its greater potential for biological nitrogen removal in wastewater treatment.

The steep increase in acquired drug resistance in Candida isolates has posed a great challenge in the clinical management of candidiasis globally. Information of genes and codon sites that are positively selected during evolution can provide insights into the mechanisms driving antifungal resistance in Candida. This study aimed to create a manually curated list of genes of Candida spp. reported to be associated with antifungal resistance in literature, and further investigate the structure-function implications of positively selected genes and mutation sites. Sequence analysis of antifungal drug resistance associated gene sequences from various species and strains of Candida revealed that ERG11 and MRR1 of C. albicans were positively selected during evolution. Four sites in ERG11 and two sites in MRR1 of C. albicans were positively selected and associated with drug resistance. These four sites (132, 405, 450, and 464) of ERG11 are predictive markers for azole resistance and have evolved over time. A well-characterized crystal structure of sterol-14-α-demethylase (CYP51) encoded by ERG11 is available in PDB. Therefore, the stability of CYP51 in complex with fluconazole was evaluated using MD simulations and molecular docking studies for two mutations (Y132F and Y132H) reported to be associated with azole resistance in literature. These mutations induced high flexibility in functional motifs of CYP51. It was also observed that residues such as I304, G308, and I379 of CYP51 play a critical role in fluconazole binding affinity. The insights gained from this study can further guide drug design strategies addressing antimicrobial resistance.

Pyracantha fortuneana (P. fortuneana), as a medicinal and edible plant resource, is rich in nutrients. In order to screen the high quality yeast used in Firebone fruit wine, 12 strains of yeast were isolated and purified from P. fortuneana fermentation broth by traditional pure culture method. They were identified by molecular biology as Pichia kudriavzevii (P. kudriavzevii) and Saccharomyces cerevisiae (S. cerevisiae), respectively. Strain HJ–2 could grow normally at 30℃, alcohol content 15%, SO₂ mass concentration 360 mg/L, pH 3.2, sucrose mass concentration 400 g/L and glucose mass concentration 250 g/L. Strain HJ–6 could grow normally at 30℃, alcohol content 3%, SO₂ concentration 360 mg/L, pH 3.2, sucrose concentration 250 g/L, glucose concentration 300 g/L. Based on the technological characteristics of fruit wine, S. cerevisiae HJ–2 has the potential of brewing P. fortuneana fruit wine. P. kudriavzevii HJ–6 has a low tolerance to ethanol and is suitable for the production of fermented beverages such as low–alcohol wine or beer.

Accurate genetic analysis is essential for the detection of pathogens as it necessitates suitable DNA extraction methods tailored to specific microorganisms such as Gram-positive bacteria. This study examined several commercial and simplified DNA extraction methods for their suitability in isothermal downstream applications. Extracted DNA was assessed using spectrophotometry, electrophoresis, polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) while its stability was inspected after five months of storage. The findings revealed variations in DNA yield, purity and integrity among the extraction methods. While extraction kits demonstrated high yield and purity, the in-house extraction techniques showed incoherent correlation between yield and purity, yet showed promise for a streamlined extraction process. The DNA acquired from all methods yielded positive amplification in PCR and LAMP. DNA extracted by kits exhibits prolonged stability than those obtained via boiling lysis. Both methods offer distinct advantages, with commercial kits providing longer stability and high-quality DNA while boiling lysis stands out for its simplicity, with shorter handling and processing periods. This study emphasizes selecting ideal extraction methods for Streptococcus agalactiae, in the prospect of aquaculture settings. In particular, successful LAMP reaction suggests that boiled extracts are feasible enough for detection, and suited for point-of-care (POC) testing where prompt detection of aquatic pathogens is often critical. Ultimately, the choice of method should be contemplated on a case-by-case basis such as the study goals, intended settings, and type of samples.