Frontiers in Microbiology最新文献

Macroalgal blooms have increasingly occurred in coastal regions worldwide. Since 2017, simultaneous green tides (Ulva prolifera) and golden tides (Sargassum horneri) have recurred annually in the Yellow Sea, forming a unique large-scale bi-macroalgal bloom. Interactions between macroalgae and their associated bacterial communities are recognized as key ecological drivers of algal bloom dynamics. In this study, the differences in phycosphere-associated bacterial communities and algae-derived metabolites between U. prolifera and S. horneri were explored using the 16S rRNA amplicon combined with broad-spectrum metabolomics. The results reveal that the diversity of phycospheric and epiphytic bacterial communities of S. horneri is significantly higher than that of U. prolifera. We observed distinct phycosphere bacterial recruitment between the two macroalgal species. Verrucomicrobiae were the stable core microbiota in the U. prolifera phycosphere, whereas Gammaproteobacteria and Bacteroidia represented the core members in that of S. horneri. Community assembly analyses indicate that deterministic processes predominantly shape the epiphytic bacterial communities, suggesting strong host selection effects. Metabolomic profiling further revealed that the metabolites secreted by U. prolifera, such as phenolic acids and organic acids, promote the proliferation and colonization of Verrucomicrobiae Rubritalea, which may enhance the stress tolerance of the host. In contrast, the amino acids, nucleotides, lipids, and their derivatives are key metabolites that promote the colonization of Gammaproteobacteria Vibrio and Marinomonas on the S. horneri surface, which may inhibit host growth through the production of algicidal substances. Together, these results suggest that U. prolifera and S. horneri can secrete different metabolites that recruit epiphytic microbial communities and influence macroalgae-bacteria interactions. These findings provide insights into the ecological mechanisms underlying host-bacteria interactions and their roles in the formation and persistence of macroalgal blooms.

Aim: This study aimed to investigate the impact of moderate physical activity during late pregnancy on the overall structure and stability of the maternal gut microbiota, with particular emphasis on microbial network interactions and their potential implications for mucosal immune resilience.

Methods: A prospective cohort study was initiated at 32 weeks of gestation, during which physical activity was assessed, and fecal samples were subsequently collected at full-term admission for delivery. Fecal samples were collected and analyzed using 16S rDNA sequencing, and daily physical activity levels were recorded. Participants were categorized into two groups based on the duration of moderate-intensity physical activity: T1 (≥30 min/day, 18 women) and T2 (<30 min/day, 5 women). Bioinformatics analyses were used to compare gut microbiota composition, diversity, and network interactions between the groups, and to assess correlations between microbial abundance and physical activity levels.

Results: Firmicutes, Bacteroidetes, Actinomycetes, and Proteobacteria were the dominant phyla in both groups. Alpha diversity and principal coordinate analysis (PCoA) showed no significant differences in overall diversity. However, LEfSe analysis revealed an enrichment of Christensenellaceae and Prevotella stercorea in the T2 group. The gut microbial network in the T1 group was more complex and stable, with predominantly positive microbial correlations. Spearman analysis indicated significant associations between physical activity levels and specific gut microbes: sedentary behavior correlated negatively with Romboutsia (p = 0.033, R = -0.445) and was positively correlated with Senegalimassilia (p = 0.043, R = 0.443), light-intensity activity correlated negatively with Phascolarctobacterium (p = 0.015, R = -0.500), and moderate-intensity activity correlated positively with Parasutterella (p = 0.040, R = 0.432).

Conclusion: Moderate physical activity during late pregnancy promotes a more stable and functionally interactive gut microbiota network. Such microbial resilience may strengthen mucosal immune regulation and reduce infection susceptibility during gestation. These findings highlight the potential of physical activity as a non-pharmacological strategy to modulate the maternal gut microbiome for improved host defense and health outcomes.

Introduction: Large interindividual variation in human gut microbiota composition and its response to interventions limits the development of novel microbiota-targeted supplements. In vitro models reflecting this interindividual variation and predicting individual in vitro microbiota responses would allow for the assessment of the potential efficacy of such interventions.

Methods: Here, we investigated whether in vitro microbiota modulation by a dietary fiber mixture is translatable to in vivo microbiota outcomes. A 12-week double blind, randomized, placebo-controlled, crossover study with a dietary fiber mixture of acacia gum (AG) and carrot powder was performed in healthy volunteers (N = 54, 45-70 years, BMI 27.3 ± 1.4 kg/m²). The in vitro platform utilized fecal samples from the same individuals who participated in the in vivo study.

Results: A significant effect on microbiota composition was shown in vivo, although with strong individual variation. The fiber intervention was mimicked in vitro by exposing each individuals' baseline microbiota to the same dietary fiber as used for the 12-weeks in vivo intervention. A significant correlation was shown between the in vitro and human fecal microbiota composition after 8- and 12-weeks intervention (p = 0.003 and p = 0.0107, respectively). Microbial taxa responding to the intervention in vitro and in vivo also showed clear overlap (p = 0.002).

Discussion: These results demonstrate that in vitro models may enable pre-study selection of donors whose microbiotas respond to a specific intervention.

Whole-genome sequencing (WGS) is increasingly used as the primary typing method for foodborne disease surveillance. It offers high-resolution cluster analysis, interoperability, and comprehensive pathogen characterization. However, implementing WGS-based foodborne surveillance also poses challenges. This paper outlines these challenges and provides practical recommendations. It requires a business plan that details the financial, technical and human resources needed, since setting up WGS-based surveillance requires substantial initial investments. During the initial phase, the per sample costs of WGS are likely higher than with traditional typing method. However, this will align or even go below that when fully transitioned to WGS-based surveillance because WGS data can be used for multiple purposes such as (sero)typing and antimicrobial and virulence characterization. It is advisable to start with a single pathogen to establish a solid foundation, with the aim of having one institutional sequencing facility. Validating accuracy and consistency of results is crucial before expanding to other pathogens. While cross-disciplinary collaboration has always played an important role in foodborne surveillance, the complexity of WGS results now makes it essential for transforming findings into effective interventions. Despite its challenges, advancements in technology and computation capabilities have made it increasingly accessible, ultimately improving public health surveillance and response.

Plant-based nutraceuticals are increasingly recognized for their bioactive compounds that promote health and assist in preventing chronic diseases. However, the rising demand has raised concerns about microbial safety, as contamination can occur at multiple stages of the production process-ranging from cultivation and harvesting to processing, storage, and distribution. Pathogens such as Escherichia coli, Salmonella, Listeria monocytogenes, and toxin-producing fungi pose risks to product quality, threaten consumer health, and contribute to antimicrobial resistance. This review provides a comprehensive overview of the sources and types of microbial contamination, associated health risks, and the shortcomings of conventional control methods. It highlights recent advancements in safety techniques, including cold plasma, ultraviolet light treatment, high hydrostatic pressure, nanocoatings, probiotic biocontrol, and AI-driven microbial monitoring. Additionally, the analysis addresses the role of regulatory frameworks, quality assurance practices, and consumer education as integral elements of a unified safety approach. It integrates technological progress, regulatory perspectives, and consumer behavior to offer a detailed guide for ensuring the microbial safety of plant-derived nutraceuticals, thereby fostering confidence in these products from production through to consumption.

Introduction: Salinity is a major abiotic stress threatening global agriculture. While some microorganisms are known to ameliorate soil salinity and promote plant growth, the underlying mechanisms, particularly for Priestia megaterium (formerly Bacillus megaterium), remain less explored.

Methods: Here, we investigated the efficacy and mechanism of P. megaterium NCT-2 in improving secondary saline soil by elemental analysis, 15N tracing, gene knockout and transcriptomics.

Results: Our results demonstrated that the NCT-2 agent significantly reduced the content of key salt ions, notably NO₃^-, Cl^-, and Na⁺ in soil. Through a combination of biochemical assays, isotope tracing, and gene knockout techniques, we identified that the aerobic assimilation pathway is the primary route for nitrate metabolism in NCT-2, with the nasC and nasD genes being crucial for this process. Furthermore, transcriptomic analysis under salt stress revealed that NCT-2 employs a multi-faceted tolerance strategy, which includes enhancing sporulation, activating antioxidant defenses (e.g., CAT, SOD), assembling flagella, and forming vesicles. Concurrently, the strain upregulates central carbon metabolism (TCA cycle, glycolysis) and amino acid synthesis to fuel these adaptive responses.

Discussion: This study provides a comprehensive theoretical foundation for using P. megaterium NCT-2 in environmental remediation and identifies key genetic targets for enhancing microbial salt tolerance.

Obesity and metabolic diseases are global health challenges, with gut microbiota playing a critical role in host fat deposition through symbiotic interactions. In recent years, the gut microbiota, as an important factor regulating fat deposition, has received widespread attention. Numerous studies have confirmed that gut microbes influence host fat accumulation by regulating energy metabolism, inflammatory response, and gut barrier function. In this review, we summarized the key roles of gut microbial metabolites, including short-chain fatty acids (SCFAs), bile acids, tryptophan metabolites, lipopolysaccharides (LPS), branched-chain amino acids (BCAAs), and trimethylamine N-oxide (TMAO) in host epigenetic regulation and lipid metabolism, and explored their regulatory mechanisms through mediated signaling pathways, including Wnt/β-catenin signaling pathway, transforming growth factor beta/SMAD3 pathway (TGF-β/SMAD3), peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). In terms of translational applications, we described the research progress and application potentials of intervention strategies, such as probiotics, prebiotics, synbiotics, postbiotics, and fecal transplantation in obesity control and animal production. Finally, we proposed the current bottlenecks and translational challenges in obesity control by precision nutrition and microecological intervention, and look forward to future directions. This review provides a theoretical basis for the in-depth understanding of the interactions between gut microbiota and host metabolism, and serves as a reference for the prevention and control of metabolic diseases by developing nutritional intervention strategies for animals.

Background: The regulatory effects of nicotine on energy balance through central and peripheral mechanisms have been reported. However, its impact on obesity and gut microbiota at safe doses remains unclear.

Results: In this study, it was found that chronic oral nicotine administration daily at relative low dose (0.5 mg/kg) significantly alleviated high-fat diet (HFD)-induced obesity phenotypes in mice, including body weight gain, fat deposits, hepatic steatosis, inflammation and metabolic dysfunction. Gut microbiota depletion and fecal microbiota transplantation (FMT) confirmed that these beneficial effects were microbiota-dependent. Metagenomic sequencing confirmed that nicotine administration reshaped gut microbiota composition, and specifically enriched the commensal genus Adlercreutzia, whose increased abundance correlated with improved biochemical indicators related to obesity. Furthermore, transplantation of Adlercreutzia reproduced anti-obesogenic effects, suggesting it was a key factor for nicotine reducing HFD-induced obesity. Untargeted metabolomics analysis combined association analysis further demonstrated that nicotine modulated host metabolic profiles via gut microbiota-metabolite axis, particularly enhancing Adlercreutzia-linked lipid metabolites involved in polyunsaturated fatty acid (PUFA) metabolism.

Conclusion: Collectively, our study elucidates the critical involvement of gut microbiota in nicotine-induced obesity amelioration, uncovers a novel Adlercreutzia-PUFA metabolic axis mediating nicotine's anti-obesity effects, and highlight Adlercreutzia potentiation as a promising microbiota-directed invention strategy for obesity and metabolic syndrome.

Denitrifying bacteria with flocculation capacity were dual-function microorganisms that can simultaneously remove nitrogen (N) and reduce suspended particles in wastewater, providing a sustainable bioremediation strategy. In this study, a novel denitrifying bacterium capable of producing bioflocculants, Thauera sp. JM12B12, was isolated and investigated. The results confirmed that this strain could completely remove NO₃ ^--N and NO₂ ^--N under microaerobic conditions with a low C/N ratio of 5, using lactate as the optimal carbon source. Notably, no other harmful inorganic N species were produced during denitrification, and total N removal efficiency consistently exceeded 93.0%. Optimal denitrification conditions include a pH range of 7-9, salinity of 0-1.5%, temperature of 25-40 °C, and static incubation. Remarkably, this strain synthesized extracellular bioflocculants during NO₃ ^--N removal, achieving 91.4% flocculation efficiency with cell-free supernatant. Genome analyses revealed a complete denitrification pathway (possessing napA, two nirS, norB, nosZ) and 80 bioflocculant-related genes (polysaccharide production and protein secretion), highlighting its dual capacity for N and suspended particle removal. PCR also confirmed key denitrification genes. Therefore, JM12B12 could be a multifunctional microbial agent for N removal and flocculation, offering a sustainable solution for low C/N wastewater treatment, particularly valuable in recirculating aquaculture systems.

Introduction: This study aimed to determine the status of soil mercury (Hg) contamination and to understand the associated soil microbial community structure and function, along with their relationships with environmental factors, in farmlands surrounding mercury mining regions.

Methods: Soil samples were collected from farmland surrounding a mercury mining region (Chuandong town, CD, Huaqiao town, DP, Bahuang town, BG, and Shuangjiang town, LT) in Tong Ren, south-western China. We analyzed soil physicochemical properties, Hg pollution indices, and bacterial community structure and function. The interactions among soil environmental factors and bacterial community structure and function were determined using correlation analysis and redundancy analysis.

Results: The soils exhibited varying degrees of Hg contamination: CD and LT soils were categorized by "light" Hg contamination, whereas DP and BG soils exhibited "moderate" Hg contamination. The potential ecological risk was "moderate" for CD soils, "considerable" for BG and LT soils, and "high" for DP soils. Long-term Hg contamination significantly increased soil bacterial community diversity and decreased bacterial community richness. Bacterial communities underwent adaptive restructuring, with Acidobacteria (16.90% relative abundance) dominating the acidic, high-Hg soils at the DP site and Proteobacteria (29.71% relative abundance) thriving in nutrient-rich conditions at the LT site. Key metal-resistant genera (Rokubacteriales, Gaiella) emerged as potential biomarkers of contamination. PICRUSt2 analysis revealed maintained metabolism potential under Hg stress, with carbohydrate metabolism and amino acid metabolism pathways collectively accounting for 26.43% of all predicted functions. Redundancy analysis identified soil pH, THg, and Gaiella were the key the factors driving the soil bacterial community function, with their independent contributions contributions to the variance being 72.83, 84.64, and 81.97%, respectively.

Discussion: These findings provide a mechanistic understanding of microbial resilience in Hg-contaminated ecosystems and identify critical leverage points for remediation strategies targeting both metal toxicity and the functional restoration of agricultural soils.