World journal of microbiology & biotechnology最新文献

Sophorolipid (SL) are glycolipid biosurfactants with growing industrial relevance as sustainable alternatives to petrochemical surfactants. This review highlights the advances in SL genetics and pathway architecture, transcriptional and process level regulation, and comparative performance of native producers versus recombinant platforms. It emphasizes the transition from empirical optimization to rational, systems guided strategies integrating advance metabolic engineering strategies including pathway optimization to divert carbon flux toward the SL module, balance redox/energy demands with growth, and tailor congener profiles. We further evaluated the current industrial feasibility, technology used by several companies highlighting progress increasing titers and productivities alongside persistent constraints in production, reliance on costly feedstocks, different fermentation methods, process parameters, and challenging downstream recovery. Key research gaps include incomplete understanding of regulatory control, limited systematic flux redistribution, and insufficient techno-economic integration. We outline future priorities for CRISPR enabled and omics guided rewiring, secretion and tolerance engineering, deployment of low cost/waste substrates, and standardized, scalable purification. These directions define a roadmap to robust, cost competitive SL manufacturing and clarify where recombinant hosts can complement or extend capabilities beyond Starmerella bombicola.

Here, ACC deaminase ACC Deaminase producing rhizobacteria, Priestia aryabhattai MD-85 (Accession no. PV155249.1) and Enterobacter cloacae MD-79 (Accession no. PV155250.1), were assessed for their potential to enhance water-deficit stress tolerance in muskmelon. Both strains produced ACC Deaminase and exhibited drought tolerance, with MD-79 showing 78.9 ± 7.6 µM α-ketobutyrate mg⁻¹ protein h⁻¹ at 18%-PEG, and MD-85 showing 68.4 ± 5.4 µM α-ketobutyrate mg⁻¹ protein h⁻¹ at 21%-PEG. Both strains produced multi-functional growth-promoting substances under PEG-induced stress, conferring their significant drought tolerance potential. Increasing water stress negatively impacted growth and physiological characteristics of soil-grown muskmelon plants. However, ACC Deaminase-producing strains, especially when applied in combination (P. aryabhattai MD-85 + E. cloacae MD-79), effectively mitigated adverse effects of drought stress. For instance, under 3%-polyethylene glycol (PEG)-induced stress in muskmelon, co-inoculation (MD-79 + MD-85) enhanced root length (44.3%), shoot length (47.6%), root dry and fresh wight ratio (40.7%), leaf dry and fresh wight ratios (51.7%), total chlorophyll (41.5%), and carotenoids (38.8%). Further, bacterial consortia significantly (p ≤ 0.05) enhanced chlorophyll colour index (56.7%), net photosynthetic rate (64.3%), Fv/Fm (50.8%), stomatal conductance (64.3%) and relative water content (62.3%) in leaf tissues of 3%-PEG-stressed muskmelon. Single/combined bacterial inoculation lowered drought-induced oxidative stress markers in muskmelon. Moreover, bacterial partners strengthened antioxidant enzymes in water-deficit affected muskmelon. The 15%-PEG + MD-79 + MD-85 treatment exhibited greater increase in catalase (79.3%), ascorbate peroxidase (65.3%), peroxidase (55.7%), and superoxide dismutase (72%), activities over their respective untreated controls. Additionally, bacterial strains modulated ion homeostasis in PEG-stressed muskmelon roots, enhancing drought tolerance. Notably, combined inoculation synergistically enhanced drought tolerance compared to single-strain treatments. This study emphasizes the potential of ACC Deaminase-producing PGPR as a sustainable and long-term strategy to improve muskmelon resilience under water-deficit condition by modulating physiological, biochemical, and ionic responses. These findings underscore the use of PGPR in drought management to enhance crop productivity and stress tolerance.

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.