World journal of microbiology & biotechnology最新文献

Dunaliella parva is halophilic green alga. Dunaliella parva may produce a large amount of starch, which has great practical value for bioethanol production. Glucose may be catalyzed by rate-limiting enzyme ADP-glucose pyrophosphorylase to produce starch. Our previous study cloned DpAGPs gene encoding ADP-glucose pyrophosphorylase (AGPase) small subunit from Dunaliella parva (D. parva). However, the function of DpAGPs remains unclear at present. To assess the influences of DpAGPs on metabolism of D. parva, this paper constructed recombinant plasmid pBI221-UbiΩ-CAT-AGPs, and transformed recombinant plasmid and empty plasmid pBI221-GFP-UbiΩ-CAT to D. parva. In transgenic D. parva overexpressing DpAGPs (sample D.parva T), both protein, carbohydrate and starch contents, AGPase activity and DpAGPs mRNA level increased compared with control sample D.parva C overexpressing the empty plasmid. Protein content of D.parva T (88.38 mg/g dry weight) increased by 11.18 mg/g DW compared with D.parva C (77.20 mg/g dry weight) at 15 d. In particular, compared with sample D.parva C, starch contents sharply increased by 34.83 mg/g dry weight (DW) and 53.51 mg/g DW, and carbohydrate contents sharply increased by 143.24 mg/g DW and 143.66 mg/g DW at 15 d/18 d in DpAGPs transgenic D.parva T. However, pigments (chlorophyll a, chlorophyll b and carotenoid) and oil contents decreased in D.parva T. The absolute oil contents of D.parva T (23.97% and 21.79%) decreased by 25.40% and 27.68% compared with D.parva C (49.37% and 49.47%) at 15 d and 18 d, respectively. This paper observed the role of DpAGPs in D. parva, providing a reference for improving microalgal starch content and enhancing the practical value of D. parva for bioethanol production. The engineered D. parva with higher starch and carbohydrate contents had a great potential for bioethanol production.

This study investigates the effects of four epigenetic treatments on the free amino-acid and central-carbon metabolite profiles of Saccharomyces cerevisiae. The objective was to assess how naturally derived epigenetic agents reshape yeast metabolism, with a particular focus on amino-acid pools and key intermediates of glycolysis and the tricarboxylic acid (TCA) cycle. Yeast cultures were grown in media supplemented with 5-azacytidine, sodium butyrate, curcumin, or green tea extract, and metabolites were quantified using LC-MS/MS. All four treatments induced marked shifts in amino-acid abundance. Essential amino acids-including leucine, tryptophan, and phenylalanine-significantly increased, with azacytidine yielding the strongest elevation (up to two-fold relative to control). Non-essential amino acids showed similar upward trends across treatments. Central-carbon metabolites such as pyruvate, acetyl-CoA, and citrate also accumulated substantially. Correlation-based and network analyses revealed coordinated modules linking amino-acid metabolism with energy-producing pathways, and enrichment analysis highlighted perturbations in gluconeogenesis and fatty-acid metabolism. Collectively, these results provide a quantitative and network-level perspective on metabolic reorganization induced by epigenetic modulators and establish a reference framework for future multi-omics investigations in yeast.

The global rise of antibiotic resistance poses a major threat to human health, driving the urgent search for novel antimicrobial strategies. Phage-derived proteins, such as endolysins and holins, represent promising alternatives to conventional antibiotics. Endolysins enzymatically degrade bacterial peptidoglycan but are often ineffective against Gram-negative bacteria due to the outer membrane. Holins, by disrupting cytoplasmic membranes, may bypass this barrier and provide a distinct antibacterial mechanism. In this study, a phage-derived endolysin (POE) and holin (Hol8) from Pseudomonas phage vB_PotS-PotUPM1 were cloned and expressed in Escherichia coli. Antibacterial activity against Pseudomonas otitidis NK1, an emerging zoonotic pathogen, was evaluated using well diffusion, plate lysis, turbidity reduction, and time-kill assays, with structural properties predicted through in silico analysis. POE, a globular protein with a single lysozyme-like domain, exhibited lytic activity only when the outer membrane was permeabilized, achieving a 40.4 ± 1.3% OD₅₉₅ reduction after 3 h at 500 µg/mL. In contrast, Hol8, a holin with four transmembrane domains, exhibited significant antibacterial activity. Crude Hol8 preparations showed bacteriostatic (MIC of 31.25 ± 0 µg/mL) and bactericidal (2× MIC of 62.50 µg/mL) activities against P. otitidis NK1, along with a broader host range activity against multiple Gram-negative and Gram-positive bacteria. The combination of POE and Hol8 showed no synergistic antibacterial effects under the tested conditions, with Hol8 showing superior efficacy. These results highlight Hol8 as a promising broad-spectrum antibacterial candidate capable of overcoming the outer membrane barrier that limits endolysin activity. The findings provide a strong foundation for further investigation of phage-derived holins as alternative therapeutics to combat multidrug-resistant bacterial infections.

Cyclic di-adenosine monophosphate (c-di-AMP) is a versatile bacterial signaling molecule involved in the regulation of cell wall metabolism, response to osmotic stress, growth, maintenance of DNA integrity, potassium homeostasis, and sporulation. Recent studies have implicated c-di-AMP in the regulation of sporulation and solventogenesis in Clostridium beijerinckii, a model solventogenic Clostridium species (SCS). In light of emerging findings, in this review, we hypothesize that c-di-AMP plays a central role in regulating solventogenesis and sporulation in C. beijerinckii, a mechanism that may also occur in some other SCS. In SCS, sporulation and solventogenesis are strongly linked, with spore formation advancing proportionally to increasing butanol concentration. Given the membrane damaging effect of butanol on vegetative cells, spore formation allows SCS to package their DNA in a robust endospore that is resistant to numerous stressors. This ensures the propagation of future generations. c-di-AMP functions as a checkpoint in spore formation and repair of DNA damage-which guarantees the assembly of wholesome DNA during sporulation-as well participating in the regulation of cell wall metabolism and membrane-damaging osmotic stress, which may mimic butanol-mediated membrane damage. These suggest that c-di-AMP may serve as a regulatory anchor that operates at the nexus between maintenance of DNA integrity, sporulation, response to osmotic stress, and ultimately, butanol biosynthesis. In this review, we explore the potential role of c-di-AMP as a regulator of sporulation and ultimately, in C. beijerinckii as a model SCS.

Surfactants are widely used across industrial and environmental applications but their extensive discharge into aquatic environments raises ecological concerns. Biosurfactants, particularly rhamnolipids (RL) produced by Pseudomonas aeruginosa, represent a sustainable alternative due to their low toxicity, high biodegradability, and superior surface-active properties. Despite these advantages, high production costs remain a major barrier to large-scale implementation. In this study, RL were produced under submerged cultivation using glycerol, soybean oil, and corn bran (CB), a low-cost multifunctional agro-industrial substrate that simultaneously provided nutrients and structural support, resulting in an RL titer of 35 g/L. The produced RL consisted predominantly of di-rhamnolipid congeners (96.8%), which are associated with enhanced surface activity and commercial applicability. To further valorize the produced biosurfactant, RL-assisted steam distillation was evaluated as a novel strategy to enhance essential oil extraction. The application of RL increased essential oil recovery by 43%, demonstrating its effectiveness as a process booster. This combined strategy highlights the potential of CB-based RL production and its application in greener, more energy-efficient extraction technologies.

Monascus pigments (MPs) are natural food colorants that have received significant attention in the food industry due to their widespread use as food additives. This study employed food-grade isopropyl myristate (IPM) at different concentrations to modulate MP biosynthesis. The results showed that adding 10 g/L IPM significantly increased pigment production, reaching a total color value of 107.957 AU/50 mL, which corresponds to a 3.49-fold increase compared to the control. Furthermore, the pigment content per unit biomass increased to 335.774 AU/g, representing a 1.378-fold improvement over the control. Visual observation and scanning electron microscopy revealed that IPM-treated mycelial pellets had smaller diameters, darker pigmentation, thicker cell walls, rougher surfaces, and higher conidia production. Untargeted metabolomic profiling identified 89 differentially expressed metabolites between the IPM-treated and control groups. KEGG pathway enrichment analysis linked these metabolites to ABC transporters, taurine and hypotaurine metabolism, and cofactor biosynthesis. Further mechanistic investigation revealed that IPM stimulates MP biosynthesis by upregulating key precursors and substrates involved in the tricarboxylic acid (TCA) cycle, glycolysis, amino acid metabolism, and cofactor biosynthesis pathways (e.g., NADPH and CoA).

Gut microbiota plays a critical role in bile acid (BA) metabolism within healthy populations, yet the differential species involved in BA metabolism in patients with Crohn's disease (CD) remains poorly characterized. To address this knowledge gap, we conducted a comparative metagenomics for nine CD patients and nine healthy controls. Integrated metagenomic species profiling and functional annotation, accompanied with species-function network analysis, reduced abundance in metabolism-associated genes and lower species-function correlation were predicted, suggesting a possible imbalance of microbial communities in CD group. Focused on functional genes involved in BA metabolism and their associated bacterial taxa, our results revealed that Anaerostipes hadrus-like (P = 0.001317), Roseburia intestinalis-like (P = 0.03542), and Coprococcus catus-like (P = 0.0005787), the microbial species related to bile salt hydrolase-coding gene, showed significantly lower abundance in CD patients. Conversely, Ruminococcus gnavus-like, related to 3α-hydroxysteroid dehydrogenase (3α-HSDH)- and 3β-HSDH-coding genes, demonstrated relatively higher abundance (P = 0.0257). Escherichia coli-like, the species for 7α-HSDH-coding genes, also exhibited higher abundance in CD group (P = 0.01044). Further network correlation analysis indicated that there was a potential association between these differential species with other co-occurring gut microbiota. Collectively, the findings identify and characterize the differential gut microbiota involved in BA metabolism in CD patients, which may provide the possible target microorganisms for future therapeutic interventions.

The function of the livestock gut microbiome in driving animal growth, health, and methane emissions is controlled by networks of interactions among microbes. A major challenge is to move beyond simply listing microbial members to understanding these interaction networks, which determine how the community functions as a whole. This review synthesizes how network analysis, combined with multi-omics data, can meet this challenge. We focus on the critical task of identifying keystone species, the disproportionately influential microbes that direct processes like fiber digestion and immune function, yet are often missed by standard surveys. We evaluate a progression of methods, from identifying correlated species to building models that integrate genomic, metabolic, and host data. This integration is key to separating true ecological relationships from statistical noise and to linking microbial presence to function. We highlight how computational techniques like metabolic modeling and machine learning are turning networks into predictive tools. Finally, we outline the path forward: field-ready studies that track microbiomes over time, the development of livestock-specific metabolic models, and analytical standards that will allow research to translate into practical strategies. The goal is to provide a framework for using network science to actively manage the microbiome, enhancing sustainable livestock production.