Journal of microbiology and biotechnology最新文献

This study investigated the anti-obesity effects of Clostridium butyricum (CLB) and the underlying mechanisms through gut microbiota modulation. High-fat diet (HFD)-fed C57BL/6 mice were orally administered CLB (1 × 10¹⁰ CFU/kg/day) for 8 weeks. CLB intervention reduced body weight gain by 13.20% and decreased fat mass (21.10 ± 2.24% vs. HFD: 23.39 ± 2.34%, P < 0.05), while partially restoring fecal butyrate levels (11.73 ± 4.99 vs. HFD: 7.27 ± 3.40 μg/g, P < 0.05). 16S rRNA gene sequencing revealed CLB selectively increased the abundance of Akkermansia, which was depleted in HFD mice. In vitro, butyrate, CLB lysate, and culture supernatant significantly enhanced the growth of Akkermansia muciniphila (AKK), indicating microbial cross-feeding. These findings demonstrate CLB alleviates obesity by restoring the abundance of AKK, partly through the production of metabolites that promote the proliferation of AKK, offering novel insights into probiotic-driven microbiota modulation for metabolic health.

This study explored the effects of genetic modifications on exopolysaccharide (EPS) of Leuconostoc mesenteroides WiKim33, which was subjected to heterotypic shock-induced adaptive laboratory evolution (ALE). We examined three strains: wild-type, ALE1, and ALE2. Among these strains, ALE1 produced the highest EPS (3.87 g/l), while ALE2 produced the lowest (3.27 g/l). Nuclear magnetic resonance analysis revealed that mutations affected the hydrodynamic diameter of EPS. The ALE1 strain had the smallest EPS (11.15 nm), while ALE2 produced the largest EPS (43.27 nm). These differences in hydrodynamic size significantly affected the physical properties of EPS films. Films incorporating EPS from ALE1 exhibited reduced water solubility and hardness compared with the film containing EPS from ALE2. Confocal laser-scanning microscopy revealed that a larger EPS hydrodynamic size induced phase separation and weakened the structural integrity of the film. The current findings highlight ALE to alter the hydrodynamic size of EPS and understand its physical properties within the resulting film.

Bovine mastitis causes huge economic losses for the dairy industry worldwide. Staphylococcus aureus (S. aureus) is an important pathogen that induces bovine mastitis, and its resistance to antibiotics has become a severe problem in bovine mastitis therapy. Therefore, the development of new treatments for this potentially fatal infection is urgently needed. Clerodendron cyrtophyllum Turcz. is a traditional Chinese medicine that has been used for the treatment of various diseases. However, its antibacterial effect on S. aureus in bovine mastitis is rarely investigated. In this study, Clerodendron cyrtophyllum ethanolic extract (CTE) was prepared, and its S. aureus-inhibting activities and antibiofilm effects were determined. The mechanisms of CTE against S. aureus were also investigated. The results showed that the growth of S. aureus was inhibited by CTE, and the minimum inhibitory concentration (MIC) of CTE was 250 μg/ml. After treatment with CTE, extracellular alkaline phosphatase (AKP), protein, and nucleic acid of S. aureus were increased, suggesting that the permeability of S. aureus cells was enhanced. Furthermore, intracellular reactive oxygen species (ROS) in S. aureus were increased, suggesting that CTE inhibited S. aureus growth by causing oxidative damage. In addition, CTE treatment suppresses biofilm formation of S. aureus, as almost 50% of biofilm was scavenged at 2× (MIC) of CTE. After CTE treatment, icaA, sarA, and sigB mRNA levels were significantly downregulated, whereas the icaR mRNA level was significantly upregulated, indicating that CTE suppressed biofilm formation by regulating expression of the biofilm formation-related genes. The findings of this study indicate that CTE could be a potential treatment for bovine mastitis-associated S. aureus.

Microalgae have emerged as a promising and sustainable platform for the production of omega-3 polyunsaturated fatty acids, offering an alternative to fish-derived sources. Among these, Microchloropsis salina (formerly Nannochloropsis salina) is particularly attractive as a candidate due to its naturally high eicosapentaenoic acid (EPA) content. In this study, bacterial supernatants from various myxobacterial strains were evaluated for their ability to enhance microalgal growth and EPA production. Remarkably, the supernatant derived from Nannocystis sp. KYC 2844 significantly improved biomass accumulation when added at 20% (v/v) to f/2 medium, increasing dry cell weight from 1.69 g/l (control) to 2.13 g/l. Although total lipid content decreased from 25.1% to 13.0%, the EPA fraction within the lipid markedly increased from 9.46% to 27.2%. As a result, the overall EPA titer reached 75.5 mg/l, representing a 1.87-fold improvement over the control. Subsequent nutrient analysis revealed that the KYC 2844 supernatant contained 127.3 ppm of ammonium (NH₄⁺), which served as a preferred nitrogen source for M. salina and delayed nitrate utilization. These findings indicate that nitrogen speciation plays a critical role in shaping microalgal lipid profiles. Collectively, this study demonstrates that microbial supernatants can serve as effective medium supplements to enhance both growth and EPA productivity in microalgae and offers a potential strategy for improving the efficiency of microalgal-based omega-3 production systems.

Ultraviolet B (UVB) radiation induces oxidative stress, contributing to skin damage and elevating the risk of chronic skin disorders. In response to growing interest in natural alternatives to synthetic compounds, this study evaluated the photoprotective effects of Kjellmaniella crassifolia ethanol extract (KCE) in UVB-exposed HaCaT keratinocytes. The cytotoxicity/cytoprotective activity of KCE was assessed using MTT, and DCF-DA assays to measure cell viability and intracellular reactive oxygen species (ROS), respectively. Apoptotic cell death was examined through nuclear staining, Annexin V/PI assays, and mitochondrial membrane potential analysis via JC-1 staining. Western blot results indicated that KCE suppressed the mitochondrial-mediated apoptotic pathway, reduced phosphorylation of MAPK and NF-κB, and activated the Nrf2/HO-1 antioxidant signaling pathway. Overall, these findings demonstrate that KCE effectively attenuates UVB-induced oxidative stress and apoptosis, highlighting its potential as a natural bioactive ingredient for skin protection in cosmeceutical applications.

Vibrio alginolyticus is an emerging zoonotic pathogen responsible for severe aquaculture and human infections, and its increasing antimicrobial resistance calls for alternative control strategies. Here, we report the isolation and characterization of the jumbo phage pVa-22, a phiKZ-like phage that infects V. alginolyticus. Morphological analysis of the phage via transmission electron microscopy revealed a large icosahedral capsid and contractile tail consistent with jumbo vibriophages. pVa-22 exhibited notable stability across broad range of temperature (4-37°C) and pH values (3-11), as well as rapid adsorption and a moderate burst-size and latent period. Host range assays revealed strong lytic activity against Vibrio species associated with foodborne illness, including V. alginolyticus and V. parahaemolyticus. Genomic analysis revealed a 233,667-bp double-stranded DNA genome encoding 242 predicted open reading frames, including multisubunit RNA polymerases and putative phage nucleus-associated proteins, which are characteristic of phiKZ-like jumbo phages. Comparative genomics demonstrated close pVa-21 relatedness but divergence in regions linked to nucleotide metabolism, tail fibers, and replication-associated genes. Functionally, pVa-22 showed weak bactericidal effects in vitro; however, it significantly enhanced larval survival in a Galleria mellonella infection model, suggesting antivirulence activity. Putative PadR-type transcriptional regulators encoded by pVa-22 may potentially influence quorum-sensing pathways, although experimental validation is required. Taken together, the findings revealed that pVa-22 is a jumbo vibriophage possessing antivirulence activity and therefore therapeutic potential, expanding the repertoire of phage-based therapeutic strategies against climate-driven Vibrio outbreaks.

Genetic engineering of mycobacteria is challenging due to their hydrophobic cell wall structure and slow growth rates. Despite these obstacles, significant progress has been made to develop genetic engineering tools to study gene function and pathogenesis in these organisms. This review comprehensively explores the current methodologies employed in the genetic modification of mycobacteria, focusing on gene knockout, knockdown, and overexpression systems. Techniques covered include homologous recombination, recombineering, transposon mutagenesis, CRISPR-Cas systems, conditional expression strategies, and phage-mediated gene delivery. The mechanism, advantages, and limitations of those methods are critically analyzed, with particular emphasis on the adaptability of these tools to various mycobacterial species. By providing a detailed comparative analysis of available genetic tools, this review is a practical guide for researchers aiming to develop targeted and efficient genetic modifications in Mycobacterium species, accelerating discoveries in pathogenesis, drug resistance, and vaccine development.

Synthetic biology has rapidly evolved from laboratory-based research to a core technology driving biomanufacturing, industrial innovation, and the global bioeconomy. Technological advancements such as next-generation sequencing, DNA synthesis, novel genome editing, and biofoundry automation are accelerating the industrial expansion and application of synthetic biology. However, despite these breakthroughs, current regulatory frameworks and societal acceptance are not in pace with technological development, creating significant barriers to the sustainable advancement of synthetic biology. This review offers a chronological analysis of synthetic biology development, examines regulatory and policy challenges, and proposes a 'co-evolutionary' model based on the 'Framework for Anticipatory Governance of Emerging Technologies' given by the Organization for Economic Co-operation and Development (OECD). Specifically, we highlight five key elements, research and development, strategic intelligence, societal trust formation, agile regulation, and international cooperation, as the foundation for mutual evolution of technology and institutional frameworks. Transforming science and technology into societal value requires essential policy support, which is a critical task for not only policymakers, but also scientists. Scientists must consider the societal context and institutional conditions in which their research operates, thereby ensuring the accountability and sustainability of science and technology. The future of synthetic biology requires a parallel approach that integrates scientific and technological advances with societal science perspectives, underpinned by collaborative governance among scientists, policymakers, and civil society.

Bifidobacterium breve is recognized as a probiotic with immune-enhancing properties. However, our previous studies revealed that this species is present at a higher relative abundance in the gut microbiome of infants with atopic dermatitis (AD). The potential functions of B. breve in the gut microbiome may vary at the strain level between infants with and without AD (non-AD). In this study, B. breve strains were isolated from the feces of infants with and without AD and analyzed whole genome sequencing and immune assay to identify strain level differences between AD and non-AD groups. Three B. breve strains were isolated from the feces of infants with AD (MHL_0001), in remission (MHL_0043), and non-AD infants (MHL_0062). The genomes of these isolates were compared to available complete genomes of B. breve strains. While the three isolates exhibited high overall genome similarity, differences in the sequence homology of immune related genes were observed between the AD strain (MHL_0001) and non-AD strain (MHL_0062). Immune assays further revealed marked differences in the anti-inflammatory effects between MHL_0001 and MHL_0062. These findings suggest that probiotic bacteria such as B. breve may adapt within the gut in response to host immune and physiological conditions. Moreover, the presence of B. breve in the gut microbiome does not necessarily guarantee beneficial effects for the host. Therefore, strain-level analysis is crucial to accurately determine the functional roles and impact of probiotic bacteria.