World journal of microbiology & biotechnology最新文献

The silkworm (Bombyx mori) has emerged as a powerful invertebrate model for gut microbiome research due to its simple yet representative gut microbiota, cost-effective rearing, and established germ-free systems. This review synthesizes current knowledge on the ecological drivers and functional roles of silkworm gut microbiota, emphasizing its interaction with host health, environmental adaptation, and biotechnological applications. The microbial community of silkworms is highly plastic, shaped by various intrinsic (developmental stage, sex) and extrinsic (diet, environmental conditions) factors. Key microbial taxa, including Enterococcus, Bacillus, Acinetobacter, Pseudomonas, and Staphylococcus, form a dynamic core community with demonstrated probiotic attributes. These microbes contribute to nutrient metabolism (such as cellulose digestion and amino acid synthesis), immune modulation (through the production of antimicrobial peptides), and detoxification (by degrading xenobiotics). Meanwhile, their dysbiosis correlates with reduced growth, silk yield, and pathogen resistance. Notably, several gut symbionts produce or stimulate natural antimicrobial proteins, including bacteriocins (such as enterococcin LX) and host-derived antimicrobial peptides, which exhibit activity against microbial pathogens. Understanding these microbial associations is crucial for developing microbe-based probiotic formulations, antimicrobial therapies, and enzyme-driven bioprocesses to enhance sericultural productivity and sustainability. Despite progress, significant gaps remain in our understanding of host-microbe coevolution, immune-microbiota crosstalk, and the genetic basis of microbial resilience. Future research integrating multi-omics approaches and gnotobiotic models will unravel mechanistic insights, enabling targeted manipulation of the silkworm microbiota for agricultural, environmental, and medical innovations.

Biosynthesized zinc oxide nanoparticles (ZnO-NP2) produced using Lactococcus lactis culture supernatant demonstrate exceptional selectivity as anticancer agents. These flower-like nanoparticles maintained 96.44% viability in normal HUVEC cells, while reducing the viability of HCT116 and K562 cancer cells to 58.92% and 39.24%, respectively, at a concentration of 0.25 mg/mL. Acridine orange-ethidium bromide staining confirmed dose-dependent apoptosis induction, with K562 cells exhibiting a combined apoptotic and necrotic population of 61.66%. Oxidative stress analysis revealed sophisticated cell-type-specific redox modulation, including a 46.9% upregulation of catalase compared to the control in HCT116 cells, elevated lipid peroxidation, and increased levels of nitric oxide and glutathione. Gene expression analysis revealed dramatic alterations in the apoptotic pathway: HCT116 cells exhibited a 29.68-fold upregulation of BAX, while K562 cells demonstrated a 0.05-fold downregulation of BCL2. Physicochemical characterization confirmed successful synthesis with protein coating (evidenced by FTIR peak at 1635.95 cm⁻¹), negative surface charge (-25 to -30 mV), and crystalline flower-like morphology. Paradoxically, ZnO-NP2 showed antioxidant activity in cell-free DPPH assays (63.15% reduction) despite pro-oxidant effects in cancer cells. ZnO-NP2 induced selective cancer cell apoptosis through modulation of oxidative stress and activation of the intrinsic apoptotic pathway in vitro, suggesting preliminary potential for development as targeted anticancer agents, pending comprehensive in vivo validation and mechanistic studies.

L-Tyrosine, an important aromatic amino acid, has broad applications in food, feed, pharmaceuticals, nutraceuticals, and materials industries, with consistently growing market demand. Conventional production methods face drawbacks such as low efficiency and significant environmental impact. In contrast, microbial cell factories offer a promising alternative due to their environmental friendliness, sustainability, and controllability. This review systematically summarizes recent advances in metabolic engineering strategies for L-tyrosine production, including key enzyme overexpression and engineering, pathway optimization, and enhancement of precursor, cofactor, and transport systems. It also explores prospective research directions to address ongoing challenges such as complex metabolic networks and product inhibition, including systems biology-guided global optimization, dynamic regulation, and diversified substrate utilization. Overall, this review aims to provide a theoretical and technical foundation for advancing efficient, economical, and sustainable L-tyrosine biomanufacturing.

The production of odd-chain fatty acids (OCFAs) is gaining increasing importance due to their diverse applications in food, chemical, and biofuel industries. These fatty acids, which are relatively rare in nature, can be produced from renewable carbon sources through microbial fermentation processes. This review covers the significance of OCFAs in the market and their occurrence, followed by a detailed exploration of their production in mixed and single strain cultures. Specifically, the anaerobic fermentation (AF) conditions and feedstocks used to produce short OCFAs (SOCFAs), such as propionic, valeric, and heptanoic acids are discussed. Additionally, the production of long OCFAs (LOCFAs) by single strains is focusing on yeast, bacteria, and microalgae. Novel approaches for LOCFAs generation from waste carbon sources are also reviewed. This work delves both into the manipulation of microbial communities covering bioaugmentation and process optimization for bioenrichment in open mixed cultures and genetic manipulation in single-strain systems. Finally, the potential for scalable and sustainable production of OCFAs through microbial processes is discussed, as well as the technological advances needed to optimize these pathways.

Salinity is a major abiotic stress limiting global maize (Zea mays L.) production. This study evaluated the biostimulant potential of pullulan, an exopolysaccharide produced by Aureobasidium pullulans ATCC 42,023, applied alone or in combination with the microalga Chlorella vulgaris, to enhance seed sprouting and initial growth under saline environments. Pullulan was biosynthesized in a 5-L bioreactor using glucose as the carbon source, achieving a concentration of 19.23 g/L (0.25 g/g sugar of yield) at an initial glucose level of 100 g/L. Seed priming with pullulan concentrations (2.5-5.0 g/L) significantly promoted coleoptile and root elongation, whereas higher levels (10 g/L) inhibited growth. Notably, the combined application of 5 g/L of pullulan + 20 mg of C. vulgaris alleviated salinity stress (EC: 3.63 dS/m) by reducing oxidative damage, sustaining root activity, and improving plant height and chlorophyll content. Overall, the combined use of pullulan and Chlorella vulgaris enhanced maize performance, highlighting their potential as sustainable seed-priming agents and a promising strategy for managing salt-affected soils in resilient and sustainable agricultural systems.

Amicoumacins are a group of NRPS-PKS antibiotics produced by Bacillus species that exhibit broad-spectrum antibacterial, anti-inflammatory, and anticancer activities. Despite their promising pharmacological potential, the regulatory mechanisms underlying their biosynthesis remain largely unexplored, hindering the development of rational approaches for yield enhancement. In this study, we investigated the regulatory function of the amiC gene in the biosynthesis of amicoumacin by Bacillus subtilis fmb60. An amiC-overexpressing strain was constructed and displayed a significant increase in total amicoumacin production, which was correlated with larger inhibition zones against both Staphylococcus aureus and Escherichia coli. Conversely, deletion of amiC led to a substantial decrease in amicoumacin yield, to only 23.5% of the wild-type level (a 4.26-fold reduction). Metabolomic profiling further confirmed that AmiC functions as a positive regulator of multiple amicoumacin derivatives. Transcriptomic analysis of the knockout strain identified 68 differentially expressed genes, with KEGG enrichment indicating significant involvement of flagellar assembly, bacterial chemotaxis, and two-component system pathways. Mechanistic insights further suggested that loss of amiC perturbs cellular metabolism by enhancing chemotaxis and regulatory signaling, thereby diverting metabolic flux away from secondary metabolite biosynthesis. Collectively, these findings demonstrate that amiC act as a key positive regulator of amicoumacin biosynthesis and represents a promising target for metabolic engineering to improve antibiotic production.

A number of technological advancements have made bioremediation an emerging and innovative technology, including its economic viability, increased competence, and natural environment friendliness. The efficiency, scalability, and specificity of conventional physical, chemical, and biological remediation techniques are still limited, despite their partial success. Recent developments in CRISPR-based genome engineering have made it possible to precisely manipulate metal transporters, detoxification enzymes, and stress-response pathways in microorganisms and plants, opening up new possibilities to improve bioremediation. This review offers a thorough and integrated examination of enzyme engineering, biosensing systems, microbial bioremediation, and CRISPR-enabled phytoremediation. This work is novel because it presents a unified roadmap for next-generation bioremediation technologies by integrating CRISPR editing with multi-omics, synthetic biology, and emerging CRISPR-based biosensors. We also go over ecological risks, current difficulties, legal issues, and potential field deployment scenarios in the future. These revelations collectively demonstrate the revolutionary potential of CRISPR in creating highly effective, sustainable, and scalable remedies for heavy metal pollution.

The extreme environment of the Antarctic has endowed microorganisms with the ability to adapt to low temperature. These cold-adapted microorganisms can maintain high biological activity even at low temperatures. To acquire microbial resources that can be applied in pollution remediation in cold regions, we isolated cold-adapted oil-degrading bacteria from soil samples collected in Fields Island, Antarctica. Through the analysis of oil spreading, surface tension and oil emulsification tests, six biosurfactant producing bacteria were screened from 125 oil-degrading strains. A cold-adapted biosurfactant-producing bacterium, Pedobacter sp. NJ-S-72 showed the largest oil spreading and better emulsifying activity and surface tension reduction FTIR and HPLC-MS analysis indicated the main component was rhamnolipid like compounds in the biosurfactant products of this train. Although Pedobacter sp. NJ-S-72 exhibits growth across a broad temperature range of 5-20 °C, its biosurfactant production activity is highest at low temperatures (5 °C). This study identifies, for the first time, a species of obligate cold-adapted biosurfactant-producing bacterium which could serve as a microbial remediation agent under low-temperature environmental conditions.