Search Results (174)

Acid mine drainage (AMD) environments feature extreme acidity (pH ≤ 2) and high heavy metal concentrations. Acidophiles survive these conditions through unique genetic adaptations and secondary metabolite (SM) pathways. Leptospirillum ferriphilum, known for its acid and heavy metal resistance, serves as a model for AMD bioremediation, though systematic multi-omics studies on its key SMs and biosynthesis pathways remain underexplored. In this study, L. ferriphilum YR01 was isolated and identified from the AMD of the Zijinshan copper mine, China. Pangenomic analysis revealed that YR01 possesses the largest number of genes (2623) among the eight sequenced L. ferriphilum strains. Comparative genomics, antiSMASH, BiG-SCAPE, and metabolomic analyses (LC-MS and HPLC-MS) were integrated to comprehensively explore its biosynthetic capacity. A total of 39 biosynthetic gene clusters (BGCs) were identified, of which 60% shared <50% similarity with known clusters, indicating substantial novel biosynthetic potential. The sequence alignment of SM biosynthetic gene clusters (BGCs) demonstrated the potential of L. ferriphilum to synthesize conserved clusters for ectoine, choline, carotenoids, terpenoids, and terpene precursors. YR01 harbors complete BGCs for all five SM types. Notably, key nonribosomal peptide synthetase (NRPS) modules implicated in N-acyl homoserine lactone (AHL) synthesis were identified. Untargeted metabolomics (LC-MS) revealed the production of diverse SMs (18 types) putatively involved in environmental adaptation, including phosphocholine, carotenoids (e.g., anteraxanthin), cholera autoinducer-1 (CAI-1), and multiple AHLs. Targeted detection (HPLC-MS) further confirmed that YR01 could produce ectoine (0.10 ng/mL) and specific AHLs (C₁₄-HSL, C₁₂-HSL, C₁₂-OH-HSL), which were beneficial for the survival of the strain in extremely acidic environments and interspecies communication through SMs. This study represents the first comprehensive multi-omics characterization of BGCs in L. ferriphilum and experimentally validates the production of key SMs. Collectively, this study provides a comprehensive elucidation of the SM biosynthetic repertoire and environmental adaptation strategies in L. ferriphilum, advancing our understanding of microbial adaptation and interspecies communication in AMD systems, and offering potential implications for biomining applications. Full article

Heat stress induces metabolic adaptations in fish, including the regulation of triglyceride (TG) synthesis/degradation to preserve cellular lipid balance and energy homeostasis. Diacylglycerol acyltransferase (DGAT) catalyzes the final step in TG synthesis. However, the molecular mechanisms by which DGAT regulates TG metabolism in heat-stressed fish remain unexplored. Our previous study suggested that miR-10c regulates dgat2 expression in genetically improved farmed tilapia (GIFT, Oreochromis niloticus) under heat stress. Here, we characterized the GIFT miR-10c precursor as a 65-nucleotide transcript yielding a 22 nt mature miRNA (oni-miR-10c). A phylogenetic analysis revealed a high level of miR-10c sequence conservation across species. A dual-luciferase reporter assay confirmed dgat2 as a direct target of miR-10c. Overexpression of miR-10c in vivo down-regulated dgat2 transcripts and DGAT2 protein. SiRNA-knockdown of dgat2 resulted in upregulation of cpt1α, fas, and lpl and downregulation of hsl, thereby reprogramming lipid metabolism in GIFT hepatocytes. Thus, the miR-10c-dgat2 regulatory axis facilitates TG hydrolysis and promotes fatty acid metabolism under heat stress. Our findings highlight miR-10c’s potential as a dgat2 inhibitor and its function in regulating lipid metabolism in heat-stressed GIFT. Our study reveals a key molecular pathway mediating thermal adaptation of energy metabolism in fish, providing novel targets for preventing heat-induced metabolic disorders. Full article

Microbial remediation of chromium-contaminated soil through extracellular electron transfer is an economical and environmentally friendly strategy. Exogenous quorum sensing (QS) signaling molecules could facilitate the process of electron transport. However, it remains unclear whether regulating QS could enhance the microbial remediation effect. In this study, exogenous N-acylated-L-homoserine lactones (AHLs) were added for the remediation of Cr(VI)-contaminated soil by S. putrefaciens. Various AHLs such as C8-HSL, C10-HSL, 3OC8-HSL, 3OC10-HSL and 3OC12-HSL were detected in the remediation, with the concentrations of 5.91 ng/L, 1.09 ng/L, 4.10 ng/L, 2.29 ng/L and 24.51 ng/L. The addition of C10-HSL and 3OC12-HSL significantly promoted the Cr(VI) reduction rates by 11.25% and 9.20%. There were also various AHLs in the Cr(VI) reduction by indigenous microorganisms. The AHLs species measured and their concentrations were C8-HSL (5.05 ng/L), C10-HSL (3.27 ng/L), C12-HSL (0.11 ng/L), 3OC8-HSL (0.11 ng/L), 3OC10-HSL (0.05 ng/L), and 3OC12-HSL (2.92 ng/L). Relative to the untreated control, supplementation with C8-HSL, C12-HSL, and 3OC12-HSL produced significant enhancements in the Cr(VI) reduction rates by 4.10%, 3.05%, and 2.24%, respectively (p < 0.05). Comparing the effects of AHL on the remediation by S. putrefaciens and indigenous microorganisms, it could be found that C10-HSL enhanced the remediation effect by increasing the reduction rates of S. putrefaciens, and 3OC12-HSL enhanced the remediation effect by increasing the reduction rates of indigenous microorganisms. This study introduces a distinctive pathway for the promotion of the microbial remediation effect and contributes to further understanding the communication mechanism between exogenous and indigenous microorganisms. Full article

Background: Obesity is a global health issue closely associated with dysregulated lipid metabolism and chronic inflammation. Effective strategies targeting both lipogenesis and inflammation are essential for managing obesity and its related metabolic disorders. Methods: This study evaluated the effects of Terminalia catappa Linn. leaf extract (TCE) on lipogenic and lipolytic pathways in high-fat diet (HFD)-induced obese mice. UPLC-QTOF-MS analysis was conducted to identify and quantify the major phenolic compounds in TCE. Mice were administered low and high doses of TCE, and various metabolic parameters, including lipid profiles, liver function markers, adipokine levels, and gene/protein expressions related to lipid metabolism and inflammation, were assessed. Results: UPLC-QTOF-MS analysis identified four major phenolic compounds in TCE—gallic acid, orientin, vitexin, and ellagic acid—with respective contents of 112.5, 163.3, 184.7, and 295.7 mg/g extract. TCE administration significantly reduced liver and adipose tissue weights, along with hepatic and adipose lipid accumulation. Both low and high doses of TCE markedly lowered serum lipid levels. Liver function was improved, as indicated by reduced levels of AST, ALT, and ALP, while BUN levels remained unchanged. On the molecular level, TCE downregulated adipogenic and lipogenic genes (PPARγ, PPARα, C/EBPα, aP2) and upregulated metabolic regulators, including leptin, adiponectin, p-HSL/HSL, and p-perilipin/perilipin, without affecting ATGL expression. TCE also suppressed pro-inflammatory cytokines such as IL-6, IL-1β, TNF-α, and TGFβ-1. Conclusions: These findings highlight the therapeutic potential of TCE in managing obesity by inhibiting lipogenesis, enhancing lipolysis, and reducing inflammation. Full article

Extracellular electron transfer is crucial in the microbial reduction of hexavalent chromium [Cr(VI)], and N-acylated-_L-homoserine lactones (AHLs) could accelerate this process. In this study, fulvic acid (FA) was used as an electron shuttle to enhance the microbial reduction process via stimulating extracellular electron transfer efficiency. Compared with 9,10-anthraquinone-2-sulfonic acid (AQS), FA had a stronger positive effect on Cr(VI) reduction by S. putrefaciens, showing the ability of stimulating S. putrefaciens to release AHLs. The concentrations of C6-HSL, C8-HSL and 3OC10-HSL increased by 11.79 ng/L, 19.82 ng/L and 3.01 ng/L after the addition of 2% FA. The bioinformation analysis indicated that AHLs could regulate the synthesis of electron shuttles by S. putrefaciens, such as riboflavin. And the addition of exogenous C6-HSL, C8-HSL, C10-HSL, C12-HSL and 3OC10-HSL increased the Cr(VI) reduction rates by 1.73%, 2.39%, 4.18%, 1.45% and 2.70%, because they could promote the release of riboflavin. It revealed a new pathway by which FA promoted microbial Cr(VI) reduction. This study also provides a novel approach for enhancing the microbial Cr(VI) reduction and a deeper understanding of the communication mechanism among microorganisms. Full article

Intramuscular fat (IMF) content determines the quality of goat meat and is regulated by the comprehensive effect of the proliferation and adipogenesis of intramuscular preadipocytes. Our previous RNA-seq data revealed that cell death-inducing DNA fragmentation factor alpha (DFFA)-like effector (CIDE) A was upregulated during the development of intramuscular fat in the longissimus dorsi muscle tissue, implying an important role in lipid homeostasis. However, the mechanism by which CIDEA, a member of the CIDE family, regulates intramuscular fat deposition in goat muscle is unknown, so we explored the function and underlying mechanism of CIDEA in goat intramuscular preadipocytes. To address this, we altered CIDEA in intramuscular preadipocytes and resolved the effect and mechanism of CIDEA in adipogenesis through RT-PCR, Western blot, triglyceride and LD determinations, CCK-8, and RNA-seq. It was found that CIDEA increased lipid droplets (LDs) and triglyceride contents and inhibited cell proliferation. Meanwhile, the lipid metabolism-related genes PPARγ, C/EBPα, SREBP1c, PLIN1, TIP47, ADFP, DGAT1, ACC, FASN, ACSL1, and FABP3 were upregulated, while the lipolysis and β-oxidation genes HSL, ACOX1, and CPT1B, as well as the proliferation marker gene CDK1, were all downregulated upon CIDEA overexpression. Differentially expressed genes in CIDEA dysregulation groups through RNA-seq were selected and were enriched in the apelin and focal adhesion signaling pathways. Specifically, the Western blot and rescue assays found that focal adhesion, but not apelin, was the key signaling pathway in CIDEA regulating lipid deposition in goat intramuscular preadipocytes. In summary, this study reveals that CIDEA promotes lipid deposition in intramuscular preadipocytes through the focal adhesion pathway and inhibits cell proliferation. This work clarifies the functional role and downstream signaling pathway of CIDEA in intramuscular fat deposition and provides theoretical support for improving meat quality by targeting key phenotype-related genes. Full article

Antibiotic misuse accelerates resistance dissemination via plasmid conjugation, but quorum sensing (QS) regulatory mechanisms remain undefined. Using Escherichia coli (E. coli) MG1655 conjugation models (RP4-7/EC600 plasmids), we demonstrate that long-chain acyl-homoserine lactones (C10/C12-HSL) enhance transfer frequency by up to 7.7-fold (200 μM C12-HSL; p < 0.001), while quorum-quenching by sub-inhibitory vanillin suppressed this effect by 95% (p < 0.0001). C12-HSL compromised membrane integrity via ompF upregulation (4-fold; p < 0.01) and conjugative pore assembly (trbBp upregulated by 1.38-fold; p < 0.05), coinciding with ROS accumulation (1.5-fold; p < 0.0001) and SOS response activation (recA upregulated by 1.68-fold; p < 0.001). Crucially, rpoS and rmf deletion mutants reduced conjugation by 65.5% and 55.8%, respectively (p < 0.001), exhibiting attenuated membrane permeability (≤65.5% reduced NPN influx; p < 0.0001), suppressed ROS (≤54% downregulated; p < 0.0001), and abolished transcriptional induction of conjugation/stress genes. Reciprocal RpoS–RMF (ribosomal hibernation factor) crosstalk was essential for AHL responsiveness, with deletions mutually suppressing expression (≤65.9% downregulated; p < 0.05). We establish a hierarchical mechanism wherein long-chain AHLs drive resistance dissemination through integrated membrane restructuring, stress adaptation, and RpoS–RMF-mediated genetic plasticity, positioning QS signaling as a viable target for curbing resistance spread. Full article

This study elucidates how the quorum-sensing (QS) signal 3OC12-HSL exacerbates enterotoxigenic E. coli (ETEC) pathogenicity and intestinal barrier dysfunction. In vitro, 3OC12-HSL enhanced ETEC C83902 growth (66.7% CFU increase at 8 h) and dysregulated stress/growth genes (e.g., eight-fold rmf upregulation under static conditions). In synthetic gut microbiota, 3OC12-HSL selectively augmented E. coli colonization (37.6% 16S rDNA increase at 12 h). Murine studies revealed 3OC12-HSL reduced jejunal villus height (381.5 μm vs. 543.2 μm in controls), elevated serum LPS, D-lactate, and DAO, and altered microbial composition (Firmicutes/Bacteroidetes imbalance). The lactonase AiiA reversed these effects by degrading 3OC12-HSL. It abrogated bacterial growth stimulation (in vitro CFU restored to baseline), normalized microbiota diversity (Shannon index recovered to control levels), suppressed pro-inflammatory cytokines (IL-6/TNF-α reduction), and restored intestinal integrity (villus length: 472.5 μm, 20.5% increase vs. ETEC-infected mice). Our findings establish AiiA as a potent quorum-quenching agent that counteracts ETEC virulence via targeted signal inactivation, highlighting its translational value. Full article

Essential fatty acids are extremely important nutrients in the diet of fish, and the balance between arachidonic acid (ARA) and eicosapentaenoic acid (EPA) is crucial for the healthy growth of fish. Six isonitrogenous and isolipidic basal diets were given to 540 juvenile fat greenling (Hexagrammos otakii) (31.4 ± 1.5 g) for 8 weeks to investigate the effects of dietary ARA/EPA ratio on growth performance, antioxidant capacity and lipid metabolism-related genes of juvenile H. otakii. The control group (A) had 7% fish oil added as the main fat source, while the experimental groups had 4% fish oil as the basic fat source, with varying proportions of ARA and EPA concentrates added to formulate five diets with varying ARA/EPA ratios (B 2.66; C 1.34; D 1.01; E 0.47; F 0.19). The experimental results revealed that adding ARA and EPA to the diet increased the percent weight gain (PWG) and feed conversion ratio (FCR) of juvenile H. otakii, and the PWG and FCR were greatest under Group E dietary conditions. The specific activities (U/mg protein) of superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (T-AOC) in the liver, as well as serum SOD and CAT were significantly higher in Groups D and E than those in other groups (p < 0.05). Malondialdehyde (MDA, nmol/g protein) content in the liver and serum was significantly lower in Group E than that in other groups (p < 0.05). Moreover, groups D and E exhibited significant increases in the specific activities (U/mg protein) of intestinal trypsin, lipase, and amylase, as well as in the intestinal villus length (p < 0.05). The incorporation of ARA and EPA into the feed reduced the expression levels of fat synthesis genes such as fas, scd1, accα, and srebp1, as well as the expression of lipolysis genes atgl and hsl. However, it also increased the expression of the lipolytic genes cpt1 and ppara. The ARA/EPA ratios in the dietary were 0.47 and 1.01, respectively, which are appropriate for enhancing growth efficiency, antioxidant enzyme activity, intestinal digestive enzyme activity and lipid metabolism regulation. Full article

Background/Objectives: Quorum Sensing (QS) refers to the communication mechanism in bacterial cells, which occurs through the production and detection of small signaling molecules to coordinate activities and monitor population size. In Gram-negative bacteria, QS is typically mediated by N-acyl-homoserine lactones (HSLs) and 2-alkyl-4(1H)-quinolone metabolites (AQ). The present study aims to develop and validate an LC-MS/MS method for detecting QS molecules and apply it to the analysis of plasma samples from burn patients with septic shock caused by Acinetobacter baumannii. Methods: The LC-MS/MS method was developed and fully validated for the quantitative, simultaneous determination of five HSLs and four AQ molecules, ultimately derived from the plasma of three patients with septic shock, with samples collected over three consecutive days. Results: The developed method proved to be both specific and selective, demonstrating a good fit and linearity over the entire range of interest. Trueness and accuracy were satisfactory. The method showed excellent intra-assay precision (CV% was lower than 15%) and limits of quantification (LOQ) ranging from 0.02 to 0.79 ng/mL. In the patients’ samples, the concentration of 3-OH-C12-HSL peaked at 1.5 ng/mL on the first day, and C7-PQS, C9-PQS, HHQ, and HQNO ranged from 0.5 to 1.5 ng/mL, peaking at 5 ng/mL in one patient on the third day. Conclusions: A method for the simultaneous determination of nine QS molecules by LC-MS/MS was developed and validated. When applied, it showed good performance for the analysis of plasma samples and could be a useful tool for an improvement in the diagnosis, prognosis, or treatment monitoring of infections in burn patients caused by Acinetobacter baumannii. Full article

The liver accounts for almost 95% of lipid metabolism in broilers and serves as a crucial metabolic organ. Stress, which occurs when broilers are exposed to a heated environment, inhibits liver metabolism, significantly impacting their growth. This experiment investigated the combination of GBE with TP to improve hepatic lipid metabolism in heat-stressed broiler chickens by inhibiting the AMPK/SREBP-1C/ACC pathway. Three hundred broilers were reared usually until 21 days and randomly divided into six groups, namely CON group, HS group, TP group (300 mg/kg), GBE100 group (GBE100 mg/kg + TP300 mg/kg), GBE300 group (GBE 300 mg/kg + TP 300 mg/kg), GBE600 (600 mg/kg + TP 300 mg/kg) groups, where the CON group was kept at 23 °C, and the HS group and the TP, GBE100, GBE300, and GBE600 groups of each medication group were kept at 35 ± 2 °C for 10 h per day. Liver and serum samples were extracted at 28 and 42 days of age, respectively. The results showed that, at 42 days of age, the GBE600 group exhibited significantly superior performance to the HS group in ADG, ADFI, and F/G (p < 0.01). Serum TG, TC, and LDL-C levels were significantly lower (p < 0.01), while HDL-C levels were significantly higher (p < 0.05). Additionally, the mRNA expression levels of LKB1, AMPK, SREBP-1C, and ACC were markedly reduced (p < 0.01). In contrast, the mRNA expression of HSL and CPT1A was significantly elevated (p < 0.01), indicating that the GBE600 was more effective in mitigating heat stress in broiler chickens at 42 days of age. It showed that the GBE600 was more effective in ameliorating heat stress in broilers at 42 days of age, thus providing an ethical basis for ameliorating the flocculation of hepatic lipid metabolism in heat-stressed broilers. Full article

The efficient characterization of compost quality is essential for optimizing its application in agriculture and soil improvement. In this study, a correlation-based approach was employed to evaluate relationships between physicochemical properties, structural features, and reactivity indicators of compost extracts—fulvic acid-like (FA-L), humic acid-like (HA-L), and dissolved organic matter (DOM)—and their respective bulk composts. The goal was to identify key compost parameters that can serve as reliable predictors of humic substance composition and bioactivity, thereby reducing reliance on labor-intensive humic substance extractions. A comprehensive set of elemental, spectroscopic (UV-vis, ATR-FTIR, ¹H-NMR), and thermal (TGA-DSC) analyses were conducted to assess the composition and stability of the extracts. Strong correlations were found between compost oxidation state (C_oxi/C), cation exchange capacity (CEC), thermal stability, and the structural characteristics of humic substances-like (HS-L) fractions, suggesting that direct compost characterization can effectively predict humic substance reactivity and agronomic potential. The findings also align with a previously developed Compost Quality Index (CQI), reinforcing the functional role of humic substances in soil fertility and nutrient retention. By establishing a simplified yet robust compost assessment framework, this study advances the potential for efficient, cost-effective evaluation methodologies for compost quality. Full article

Two novel marine hydrogen- and sulfur-oxidizing bacteria, designated HSL1-7^T and HSL3-1^T, were isolated from mangrove sediments from Fujian Province, China. Strain HSL1-7^T exhibited Gram-negative, rod-shaped to slightly curved morphology with polar flagellum-driven motility, whereas strain HSL3-1^T was Gram-negative, rod-shaped and non-motile. Strain HSL1-7^T and HSL3-1^T were obligate chemolithoautotrophs, capable of using molecular hydrogen and thiosulfate as an energy source, and molecular oxygen and elemental sulfur as the electron acceptors for growth. Cellular fatty acid profiles revealed similar predominant components (C_16:1ω7c, C_16:0, C_18:1ω7c, and C_14:0) in both strains. Strains HSL1-7^T and HSL3-1^T were strongly diazotrophic, as demonstrated by ¹⁵N₂ fixation when a fixed nitrogen source was absent from the growth medium. The DNA G+C contents of strains HSL1-7^T and HSL3-1^T were determined to be 36.1% and 57.3%, respectively. Based on the 16S rRNA gene sequences, strains HSL1-7^T and HSL3-1^T exhibited the highest sequence similarities with Sulfurimonas marina B2^T (98.5% and 94.45%, respectively). Notably, the 16S rRNA gene sequence similarity between strains HSL1-7^T and HSL3-1^T was 93.19%, indicating that they represent distinct species within the genus Sulfurimonas. Comparative genomic analyses revealed the presence of diverse metabolic profiles in strains HSL1-7^T and HSL3-1^T, including carbon fixation, hydrogen oxidation, sulfur oxidation, and nitrogen fixation. The combined phenotypic, chemotaxonomic, and phylogenetic evidence, including average nucleotide identity and in silico DNA-DNA hybridization values, shows that strains HSL1-7^T and HSL3-1^T represent two novel species of the genus Sulfurimonas for which the names Sulfurimonas microaerophilic sp. nov. and Sulfurimonas diazotrophicus sp. nov. are proposed, with the type strains HSL1-7^T (=MCCC 1A18899^T = KCTC 25640^T) and HSL3-1^T (=MCCC 1A18844^T), respectively. Full article

This study investigated the mechanism by which N-acyl-homoserine lactone (AHL) signaling molecules influence ammonia-oxidizing microorganisms (AOMs) under inhibitory conditions. In laboratory-scale sequential batch reactors (SBRs), the effects of different AHLs (C6-HSL and C8-HSL) on the metabolic activity, microbial community structure, and quorum sensing (QS) system response of AOMs were examined. Caffeic acid, 1-octyne, and allylthiourea were used as ammoxidation inhibitors. The results indicated that under inhibitory conditions, AHLs effectively reduced the loss of ammonia oxidation activity and enhanced the resistance of AOMs to unfavorable environments. Additionally, AHLs enriched AOMs in the microbial community, wherein C6-HSL significantly increased the abundance of amoA genes in AOMs. Furthermore, AHLs maintained the activity of QS-related genes and preserved the communication ability between microorganisms. Correlation analysis revealed a positive relationship between AOMs and QS functional bacteria, suggesting that AHLs can effectively regulate the ammonia oxidation process. Overall, exogenous AHLs can improve the metabolic activity and competitive survival of AOMs under inhibitory conditions. Full article

The consumption of an unbalanced diet, such as a high-fat diet, is strongly associated with hyperlipidemia and significantly contributes to the development of cardiovascular and cerebrovascular diseases, which are the leading causes of death worldwide. Globally, about 17.9 million people die of cardiovascular disease each year (WHO 2023). Probiotics have emerged as a promising intervention to alleviate hyperlipidemia. Therefore, this study investigates the effects of Lactobacillus fermentum 166 (LF-166), isolated from yak yogurt in the Sichuan Tibetan area, on lipid metabolism in the liver and gut microbiota of high-fat-diet-induced hyperlipidemic mice. The results revealed that the Lactobacillus fermentum 166 (LF-166) treatment reduced the body weight and decreased the blood and liver lipid levels in these mice. Based on the histopathological findings, LF-166 could alleviate liver steatosis and colon injury. Additionally, 16S rRNA sequencing of the mice’s colonic contents showed that LF-166 reduced the Firmicutes/Bacteroidetes (F/B) value and enhanced the richness and diversity of the gut microbiota. LF-166 regulated hepatic lipid metabolism through the up-regulation of the genes Lxr, Ampkα, Fxr, Hsl, and Atgl and the down-regulation of C/ebpα and Pparγ in the liver; it also regulated intestinal lipid metabolism by up-regulating Abcg5 and Abcg8 in the ileum and down-regulating the expression of the genes Npc1l1, Asbt, and Ibabp. Thus, LF-166 may inhibit hyperlipidemia progression by modulating the expression of key genes involved in hepatic lipid metabolism, influencing the intestinal microbiota through the liver–gut axis, and regulating systemic lipid metabolism. Full article