Combining microbiome and pseudotargeted metabolomics revealed the alleviative mechanism of Cupriavidus sp. WS2 on the cadmium toxicity in Vicia unijuga A.Br.

Cadmium (Cd) pollution is one of the most severe toxic metals pollution in grassland. Vicia unijuga (V. unijuga) A.Br. planted nearby the grassland farming are facing the risk of high Cd contamination. Here, we investigated the beneficial effects of a highly Cd tolerant rhizosphere bacterium, Cupriavidus sp. WS2, on Cd contaminated V. unijuga. Through plot experiments, we set up four groups of treatments: the control group (without WS2 or Cd), the Cd group (with only Cd addition), the WS2 group (with only WS2 addition), and the WS2/Cd group (with WS2 and Cd addition), and analyzed the changes in physiological indicators, rhizosphere microorganisms, and stem and leaf metabolites of V. unijuga. Results of physiological indicators indicated that Cupriavidus sp. WS2 had strong absorption and accumulation capacity of Cd, exogenous addition of strain WS2 remarkably decreased the Cd concentrations, and increased the plant heights, the biomass, the total protein concentrations, the chlorophyll contents and the photosynthetic rate in stems and leaves of V. unijuga under Cd stress. Cd treatment increased the abundance of Cd tolerant bacterial genera in rhizosphere microbiome, but these genera were down-regulated in the WS2/Cd group. Pseudotargeted metabolomic results showed that six common differential metabolites associated with antioxidant stress were increased after co-culture with WS2. In addition, WS2 activated the antioxidant system including glutathione (GSH) and catalase (CAT), reduced the contents of oxidative stress markers including malondialdehyde (MDA) and hydrogen peroxide (H2O2) in V. unijuga under Cd stress. Taken together, this study revealed that Cupriavidus sp.WS2 alleviated the toxicity of V. unijuga under Cd exposure by activating the antioxidant system, increasing the antioxidant metabolites, and reducing the oxidative stress markers.

Plasma metabolic signatures for intracranial aneurysm and its rupture identified by pseudotargeted metabolomics.

BACKGROUND AND AIMS: The vital metabolic signatures for IA risk stratification and its potential biological underpinnings remain elusive. Our study aimed to develop an early diagnosis model and rupture classification model by analyzing plasma metabolic profiles of IA patients. MATERIALS AND METHODS: Plasma samples from a cohort of 105 participants, including 75 IA patients in unruptured and ruptured status (UIA, RIA) and 30 control participants were collected for comprehensive metabolic evaluation using ultra-high-performance liquid chromatography-mass spectrometry-based pseudotargeted metabolomics method. Furthermore, an integrated machine learning strategy based on LASSO, random forest and logistic regression were used for feature selection and model construction. RESULTS: The metabolic profiling disturbed significantly in UIA and RIA patients. Notably, adenosine content was significantly downregulated in UIA, and various glycine-conjugated secondary bile acids were decreased in RIA patients. Enriched KEGG pathways included glutathione metabolism and bile acid metabolism. Two sets of biomarker panels were defined to discriminate IA and its rupture with the area under receiver operating characteristic curve of 0.843 and 0.929 on the validation sets, respectively. CONCLUSIONS: The present study could contribute to a better understanding of IA etiopathogenesis and facilitate discovery of new therapeutic targets. The metabolite panels may serve as potential non-invasive diagnostic and risk stratification tool for IA.

Kynurenic acid mediates bacteria-algae consortium in resisting environmental cadmium toxicity.

Cadmium (Cd2+) is a toxic heavy metal in the environment, posing severe damage to animal health and drinking water safety. The bacteria-algae consortium remediates environmental Cd2+ pollution by secreting chelating reagents, but the molecular mechanisms remain elusive. Here, we showed that Cellulosimicrobium sp. SH8 isolated from a Cd2+-polluted lake could interact with Synechocystis sp. PCC6803, a model species of cyanobacteria, in strengthening Cd2+ toxicity resistance, while SH8 or PCC6803 alone barely immobilized Cd2+. In addition, the SH8-PCC6803 consortium, but not SH8 alone, could grow in a carbon-free medium, suggesting that autotrophic PCC6803 enabled the growth of heterotrophic SH8. Totally, 12 metabolites were significantly changed when SH8 was added to PCC6803 culture in the presence of Cd2+ (PCC6803/Cd2+). Among them, kynurenic acid was the only metabolite that precipitated Cd2+. Remarkably, adding kynurenic acid increased the growth of PCC6803/Cd2+ by 14.1 times. Consistently, the expressions of kynA, kynB, and kynT genes, known to be essential for kynurenic acid synthesis, were considerably increased when SH8 was added to PCC6803/Cd2+. Collectively, kynurenic acid secreted by SH8 mitigates Cd2+ toxicity for algae, and algae provide organic carbon for the growth of SH8, unveiling a critical link that mediates beneficial bacteria-algae interaction to resist Cd2+.

Microbiome analysis combined with targeted metabolomics reveal immunological anti-tumor activity of icariside I in a melanoma mouse model.

Recent studies report that the gut microbiome can enhance systemic and antitumor immunity by modulating responses to antibody immunotherapy in melanoma patients. In this study, we found that icariside I, a novel anti-cancer agent isolated from Epimedium, significantly inhibited B16F10 melanoma growth in vivo through regulation of gut microbiota and host immunity. Oral administration of icariside I improved the microbiota community structure with marked restoration of Lactobacillus spp. and Bifidobacterium spp. abundance in the cecal contents of tumor-bearing mice. We also found that icariside I improves the levels of microbiota-derived metabolites such as short-chain fatty acids (SCFAs) and indole derivatives, consequently promoting repair of the intestinal barrier and reducing systemic inflammation of tumor-bearing mice. Icariside I exhibited strong immunological anti-tumor activity, directly manifested by up-regulation of multiple lymphocyte subsets including CD4+ and CD8+ T cells or NK and NKT cells in peripheral blood of tumor-bearing mice. Collectively, these results suggest that icariside I, via its microbiome remodeling and host immune regulation properties, may be developed as an anticancer drug.

A newly isolated bacterium Comamonas sp. XL8 alleviates the toxicity of cadmium exposure in rice seedlings by accumulating cadmium.

Cadmium (Cd) is a typical heavy-metal highly accumulating in crops and drinking water, thus posing a severe health risk for human health. In this study, we firstly isolated 24 Cd-resistant bacteria from the heavy-metals contaminated soil at Daye Iron Ore, in which Comamonas sp. XL8 exhibited a high resistance and strong accumulation capacity to Cd. After absorption, Comamonas sp. XL8 could biosynthesize intracellular Cd-nanoparticles (CdNPs), which has not been reported in characteristics of Comamonas genus before. We found that the gene expressions of cadA and bmtA related to Cd transportation and binding in strain XL8 were significantly upregulated with Cd exposure, suggesting that genes cadA and bmtA may contribute to the formation of CdNPs. Of particular note, the co-inoculation of Comamonas sp. XL8 and rice seedlings (Oryzae sativa L.) significantly decreased the oxidative stress-induced by Cd accumulation and subsequently alleviated toxicity of Cd exposure. Our results reveal the biochemical process of Cd accumulation in Comamonas sp. XL8 by forming CdNPs, showing that it has great potential for effective bioremediation of environmental Cd exposure.

Characterization of a high cadmium accumulating soil bacterium, Cupriavidus sp. WS2.

Cadmium (Cd) is one of the most harmful heavy-metals, its accumulation in crops can lead to severe ecological and healthy problems. Bioremediation using microbes to remove Cd or reduce the bioavailability of Cd is considered as a promising approach for Cd pollution control. Here, we described the isolation and characterization of a high Cd-accumulating bacterial strain, Cupriavidus sp. WS2, from the heavy-metals contained soil at the Wuhan Iron and Steel Company area. WS2 can survive under the high Cd conditions and immobilize Cd by biosynthesizing intracellular Cd-containing nanoparticle inclusions. In the co-inoculation test WS2 also significantly decreased the accumulation of Cd in rice seedlings. All our results suggested that Cupriavidus sp. WS2 may harbor a great potential for the bioremediation applications of Cd pollution.

Involvement of the Acr3 and DctA anti-porters in arsenite oxidation in Agrobacterium tumefaciens 5A.

Microbial arsenite (AsIII) oxidation forms a critical piece of the arsenic cycle in nature, though our understanding of how and why microorganisms oxidize AsIII remains rudimentary. Our model organism Agrobacterium tumefaciens 5A contains two distinct ars operons (ars1 and ars2) that are similar in their coding region content. The ars1 operon is located nearby the aio operon that is essential for AsIII oxidation. The AsIII/H(+) anti-porters encoded by acr3-1 and acr3-2 are required for maximal AsIII and antimonite (SbIII) resistance, but acr3-1 (negatively regulated by ArsR-1) appears more active in this regard and also required for AsIII oxidation and expression of aioBA. A malate-phosphate anti-porter DctA is regulated by RpoN and AsIII, and is required for normal growth with malate as a sole carbon source. Qualitatively, a ΔdctA mutant was normal for AsIII oxidation and AsIII/SbIII resistance at metalloid concentrations inhibitory to the Δacr3-1 mutant; however, aioBA induction kinetics was significantly phase-shift delayed. Acr3 involvement in AsIII/SbIII resistance is reasonably well understood, but the role of Acr3 and DctA anti-porters in AsIII oxidation and its regulation is unexpected, and suggests that controlled AsIII trafficking across the cytoplasmic membrane is important to a process understood to occur in the periplasm.

Lysobacter arseniciresistens sp. nov., an arsenite-resistant bacterium isolated from iron-mined soil.

A Gram-negative, aerobic, motile, rod-shaped, arsenite [As(III)]-resistant bacterium, designated strain ZS79(T), was isolated from subsurface soil of an iron mine in China. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain ZS79(T) clustered closely with strains of five Lysobacter species, with 96.9, 96.1, 96.0, 95.8 and 95.3% sequence similarities to Lysobacter concretionis Ko07(T), L. daejeonensis GH1-9(T), L. defluvii IMMIB APB-9(T), L. spongiicola KMM 329(T) and L. ruishenii CTN-1(T), respectively. The major cellular fatty acids were iso-C(15:0) (28.6%), iso-C(17:1)ω9c (19.9%), iso-C(16:0) (13.6%), iso-C(11:0) (12.6%) and iso-C(11:0) 3-OH (12.4%). The genomic DNA G+C content was 70.7 mol% and the major respiratory quinone was Q-8. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and an unknown phospholipid. On the basis of morphological and physiological/biochemical characteristics, phylogenetic position and chemotaxonomic data, this strain is considered to represent a novel species of the genus Lysobacter, for which the name Lysobacter arseniciresistens sp. nov. is proposed; the type strain is ZS79(T) (=CGMCC 1.10752(T)=KCTC 23365(T)).

Arenimonas metalli sp. nov., isolated from an iron mine.

A Gram-staining-negative, aerobic, rod-shaped bacterium (CF5-1(T)) was isolated from Hongshan Iron Mine, Daye City, Hubei province, China. The major cellular fatty acids (>10%) were iso-C(16:0), iso-C(15:0), C(16:1)ω7c alcohol and iso-C(17:1)ω9c. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major respiratory quinone was Q-8. The genomic DNA G+C content was 70.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CF5-1(T) was most closely related to Arenimonas malthae (95.3% gene sequence similarity), Arenimonas oryziterrae (94.7%), Arenimonas donghaensis (94.6%) and Arenimonas composti (94.5%). A taxonomic study using a polyphasic approach showed that strain CF5-1(T) represents a novel species of the genus Arenimonas, for which the name Arenimonas metalli sp. nov. is proposed. The type strain is CF5-1(T) ( = CGMCC 1.10787(T) = KCTC 23460(T) = CCTCC AB 2010449(T)).