Regulation Of Metabolites Research Articles

Common scab disease-induced changes in geocaulosphere microbiome assemblages and functional processes in landrace potato (Solanum tuberosum var. Rongpuria) of Assam, India.

Common scab (CS) caused by pathogenic Streptomyces spp. plays a decisive role in the qualitative and quantitative production of potatoes worldwide. Although the CS pathogen is present in Assam's soil, disease signs and symptoms are less obvious in the landrace Rongpuria potatoes that indicate an interesting interaction between the plant and the geocaulosphere microbial population. Toward this, a comparative metagenomics study was performed to elucidate the geocaulosphere microbiome assemblages and functions of low CS-severe (LSG) and moderately severe (MSG) potato plants. Alpha diversity indices showed that CS occurrence modulated microbiome composition and decreased overall microbial abundances. Functional analysis involving cluster of orthologous groups (COG) too confirmed reduced microbial metabolism under disease incidence. The top-three most dominant genera were Pseudomonas (relative abundance: 2.79% in LSG; 12.31% in MSG), Streptomyces (2.55% in LSG; 5.28% in MSG), and Pantoea (2.30% in LSG; 3.51% in MSG). As shown by the high Pielou's J evenness index, the potato geocaulosphere core microbiome was adaptive and resilient to CS infection. The plant growth-promoting traits and potential antagonistic activity of major taxa (Pseudomonads, non-pathogenic Streptomyces spp., and others) against the CS pathogen, i.e., Streptomyces scabiei, point toward selective microbial recruitment and colonization strategy by the plants to its own advantage. KEGG Orthology analysis showed that the CS infection resulted in high abundances of ATP-binding cassette transporters and a two-component system, ubiquitous to the transportation and regulation of metabolites. As compared to the LSG metagenome, the MSG counterpart had a higher representation of important PGPTs related to 1-aminocyclopropane-1-carboxylate deaminase, IAA production, betaine utilization, and siderophore production.

An integrated strategy to study the combination mechanisms of Bupleurum chinense DC and Paeonia lactiflora Pall for treating depression based on correlation analysis between serum chemical components profiles and endogenous metabolites profiles

Ethnopharmacological relevanceBupleurum chinense DC-Paeonia lactiflora Pall (BCD-PLP) is a common clinical herb pair in traditional Chinese medicine (TCM) prescriptions commonly used to treat depression. However, its combination mechanisms with its anti-depressive effects remain highly unclear. Aim of the studyHere, an effective strategy has been developed to study the combination mechanisms of Bupleurum chinense DC (BCD) and Paeonia lactiflora Pall (PLP) by integrating serum pharmacochemistry analysis, metabolomics technology, and molecular docking technology. Materials and methodsFirst, the depression model rats were replicated by the chronic unpredictable mild stress (CUMS) procedure, and the difference in the chemical composition in vivo before and after the combination of BCD and PLP was analyzed by integrating background subtraction and multivariate statistical analysis techniques. Then, UPLC/HRMS-based serum metabolomics was performed to analyze the synergistic effect on metabolite regulation before and after the combination of BCD and PLP. Further, the correlation analysis between the differential exogenous chemical components and the differential endogenous metabolites before and after the combination was employed to dissect the combination mechanisms from a global perspective of combining metabolomics and serum pharmacochemistry. Finally, the molecular docking between the differential chemical components and the key metabolic enzymes was applied to verify the regulatory effect of the differential exogenous chemical components on the differential endogenous metabolites. ResultsThe serum pharmacochemistry analysis results demonstrated that the combination of BCD and PLP could significantly affect the content of 10 components in BCD (including 5 prototype components were significantly decreased and 5 metabolites were significantly increased) and 8 components in PLP (including 4 prototype components and 3 metabolites were significantly increased, 1 metabolite was significantly decreased), which indicated that the combination could enhance BCD prototype components' metabolism and the absorption of the PLP prototype components. Besides, metabolomics results indicated that the BCD-PLP herb pair group significantly reversed more metabolites (8) than BCD and PLP single herb group (5 & 4) and has a stronger regulatory effect on metabolite disorders caused by CUMS. Furthermore, the correlation analysis results suggested that saikogenin F and saikogenin G were significantly positively correlated with the endogenous metabolite itaconate, an endogenous anti-inflammatory metabolite; and benzoic acid was significantly positively correlated with D-serine, an endogenous metabolite with an antidepressant effect. Finally, the molecular docking results further confirmed that the combination of BCD and PLP could affect the activities of cis-aconitic acid decarboxylase and D-amino acid oxidase by increasing the in vivo concentration of saikogenin F and benzoic acid, which further enhances its anti-inflammatory activity and anti-depressive effect. ConclusionsIn this study, an effective strategy has been developed to study the combination mechanisms of BCD and PLP by integrating serum pharmacochemistry analysis, multivariate statistical analysis, metabolomics technology, and molecular docking technology. Based on this strategy, the present study indicated that the combination of BCD and PLP could affect the activities of cis-aconitic acid decarboxylase and D-amino acid oxidase by increasing the concentration of saikogenin F and benzoic acid in vivo, which further enhances its anti-depressive effect. In short, this strategy will provide a reliable method for elucidating the herb-herb compatibility mechanism of TCM.

Zearalenone disturbs the reproductive-immune axis in pigs: the role of gut microbial metabolites

BackgroundExposure to zearalenone (ZEN, a widespread Fusarium mycotoxin) causes reproductive toxicity and immunotoxicity in farm animals, and it then poses potential threats to human health through the food chain. A systematic understanding of underlying mechanisms on mycotoxin-induced toxicity is necessary for overcoming potential threats to farm animals and humans. The gastrointestinal tract is a first-line defense against harmful mycotoxins; however, it remains unknown whether mycotoxin (e.g., ZEN)-induced toxicity on the reproductive-immune axis is linked to altered gut microbial metabolites. In this study, using pigs (during the three phases) as an important large animal model, we investigated whether ZEN-induced toxicity on immune defense in the reproductive-immune axis was involved in altered gut microbial-derived metabolites. Moreover, we observed whether the regulation of gut microbial-derived metabolites through engineering ZEN-degrading enzymes counteracted ZEN-induced toxicity on the gut-reproductive-immune axis.ResultsHere, we showed ZEN exposure impaired immune defense in the reproductive-immune axis of pigs during phase 1/2. This impairment was accompanied by altered gut microbial-derived metabolites [e.g., decreased butyrate production, and increased lipopolysaccharides (LPS) production]. Reduction of butyrate production impaired the intestinal barrier via a GPR109A-dependent manner, and together with increased LPS in plasma then aggravated the systemic inflammation, thus directly and/or indirectly disturbing immune defense in the reproductive-immune axis. To validate these findings, we further generated recombinant Bacillus subtilis 168-expressing ZEN-degrading enzyme ZLHY-6 (the Bs-Z6 strain) as a tool to test the feasibility of enzymatic removal of ZEN from mycotoxin-contaminated food. Notably, modified gut microbial metabolites (e.g., butyrate, LPS) through the recombinant Bs-Z6 strain counteracted ZEN-induced toxicity on the intestinal barrier, thus enhancing immune defense in the reproductive-immune axis of pigs during phase-3. Also, butyrate supplementation restored ZEN-induced abnormalities in the porcine small intestinal epithelial cell.ConclusionsAltogether, these results highlight the role of gut microbial-derived metabolites in ZEN-induced toxicity on the gut-reproductive-immune axis. Importantly, targeting these gut microbial-derived metabolites opens a new window for novel preventative strategies or therapeutic interventions for mycotoxicosis associated to ZEN.

Bacteroides fragilis participates in the therapeutic effect of methotrexate on arthritis through metabolite regulation.

Methotrexate (MTX) is a preferred disease-modifying anti-rheumatic drug in the management of rheumatoid arthritis (RA). However, the toxicity and inefficiency of MTX limit its clinical application. Gut microbiota has been implicated in the side effects and efficacy of MTX. In this study, the analysis of the gut microbiota in RA patients revealed that the abundances of intestinal Bacteroides fragilis was reduced after MTX treatment. We observed that MTX has no obvious therapeutic effect in the absence of B. fragilis, while transplantation of B. fragilis restored the efficacy of MTX in antibiotics-pretreated collagen-induced arthritis (CIA) mice. In addition, B. fragilis gavage was accompanied by an increase in butyrate. Supplementation of butyrate restored the response to MTX in gut microbiota-deficient mice, to a similar level achieved by B. fragilis gavage. These results show that gut microbiota-regulated butyrate plays an essential role in the efficacy of MTX, which will provide new strategies to improve the effectiveness of methotrexate in RA treatment.

Metabolomic analysis on the mechanism of nanoselenium alleviating cadmium stress and improving the pepper nutritional value

Selenium (Se) maintains soil-plant homeostasis in the rhizosphere and regulates signaling molecules to mitigate cadmium (Cd) toxicity. However, there has been no systematic investigation of the effects of nano-selenium (nano-Se) on the regulation of non-target metabolites and nutritional components in pepper plants under Cd stress. This study investigated the effects of Cd-contaminated soil stress and nano-Se (1, 5, and 20mg/L) on the metabolic mechanism, fruit nutritional quality, and volatile organic compounds (VOCs) composition of pepper plants. The screening of differential metabolites in roots and fruit showed that most were involved in amino acid metabolism and capsaicin production. Amino acids in roots (Pro, Trp, Arg, and Gln) and fruits (Phe, Glu, Pro, Arg, Trp, and Gln) were dramatically elevated by nano-Se biofortification. The expression of genes of the phenylpropane-branched fatty acid pathway (BCAT, Fat, AT3, HCT, and Kas) was induced by nano-Se (5mg/L), increasing the levels of capsaicin (29.6%), nordihydrocapsaicin (44.2%), and dihydrocapsaicin (45.3%). VOCs (amyl alcohol, linalool oxide, E-2-heptaldehyde, 2-hexenal, ethyl crotonate, and 2-butanone) related to crop resistance and quality were markedly increased in correspondence with the nano-Se concentration. Therefore, nano-Se can improve the health of pepper plants by regulating the capsaicin metabolic pathway and modulating both amino acid and VOC contents.

Metabonomic profiling of clubroot-susceptible and clubroot-resistant radish and the assessment of disease-resistant metabolites.

Plasmodiophora brassicae causes a serious threat to cruciferous plants including radish (Raphanus sativus L.). Knowledge on the pathogenic regularity and molecular mechanism of P. brassicae and radish is limited, especially on the metabolism level. In the present study, clubroot-susceptible and clubroot-resistant cultivars were inoculated with P. brassicae Race 4, root hairs initial infection of resting spores (107 CFU/mL) at 24 h post-inoculation and root galls symptom arising at cortex splitting stage were identified on both cultivars. Root samples of cortex splitting stage of two cultivars were collected and used for untargeted metabonomic analysis. We demonstrated changes in metabolite regulation and pathways during the cortex splitting stage of diseased roots between clubroot-susceptible and clubroot-resistant cultivars using untargeted metabonomic analysis. We identified a larger number of differentially regulated metabolites and heavier metabolite profile changes in the susceptible cultivar than in the resistant counterpart. The metabolites that were differentially regulated in both cultivars were mostly lipids and lipid-like molecules. Significantly regulated metabolites and pathways according to the P value and variable important in projection score were identified. Moreover, four compounds, including ethyl α-D-thioglucopyranoside, imipenem, ginsenoside Rg1, and 6-gingerol, were selected, and their anti-P. brassicae ability and effects on seedling growth were verified on the susceptible cultivar. Except for ethyl α-D-thioglucopyranoside, the remaining could inhibit clubroot development of varing degree. The use of 5 mg/L ginsenoside Rg1 + 5 mg/L 6-gingerol resulted in the lowest disease incidence and disease index among all treatments and enhanced seedling growth. The regulation of pathways or metabolites of carbapenem and ginsenoside was further explored. The results provide a preliminary understanding of the interaction between radish and P. brassicae at the metabolism level, as well as the development of measures for preventing clubroot.

Classification, Distribution, Biosynthesis, and Regulation of Secondary Metabolites in Matricaria chamomilla

Matricaria chamomilla is a multi-use aromatic medicinal plant, and is known to be one of the oldest medicinal plants in the world. M. chamomilla contains abundant volatile oils, of which terpenes and flavonoids are the main medicinal active ingredients, including chamazulene and α-bisabolol. M. chamomilla is often used to treat flatulence, inflammation, and other disorders. It is also used for pain relief and sedation. In recent years, many studies have examined the medicinally active ingredients, pharmacological efficacy, plant physiology, and other aspects of M. chamomilla. Here, we summarize studies on the secondary metabolites of medicinally active components in M. chamomilla, with respect to their biosynthesis pathways and regulation.

A Jasmonate-Responsive ERF Transcription Factor Regulates Steroidal Glycoalkaloid Biosynthesis Genes in Eggplant

Steroidal glycoalkaloids (SGAs) are a class of cholesterol-derived anti-nutritional defense compound that are produced in species of the genus Solanum, such as tomato (S. lycopersicum), potato (S. tuberosum), and eggplant (S. melongena). However, the regulation of defense-related metabolites in eggplant remains underexplored. In tomato and potato, the JASMONATE-RESPONSIVE ETHYLENE RESPONSE FACTOR 4 (JRE4) transcription factor positively regulates a large number of genes involved in SGA biosynthesis. Here, we report that the overexpression of eggplant JRE4 (SmJRE4) induces numerous metabolic genes involved in SGA biosynthesis in leaves. We demonstrate the jasmonate-dependent induction of SmJRE4 and its downstream metabolic genes and show that ethylene treatment attenuates this induction. Our findings thus provide molecular insights into SGA biosynthesis and its regulation in this major crop.

Adaptive Responses of Four Medicinal Plants to High Altitude Oxidative Stresses through the Regulation of Antioxidants and Secondary Metabolites

The conservation of medicinal plants, particularly endangered or endemic species, is of the utmost importance, especially in light of inevitable climate change and its consequences. Species inhabiting high altitudes adopt exceptional defense mechanisms in response to abiotic stresses as a survival strategy. The objective of the current study was to investigate the effects of altitudinal variations on secondary metabolite accumulation and antioxidant enzyme capacity in four plants (Cotoneaster orbicularis, Crataegus x sinaica, Echinops spinosissimus subsp. Spinosissimus, and Tanacetum sinaicum) growing naturally on the Sinai Peninsula’s high mountains. Plant leaves and soil samples were collected from three altitudes between 1500 and 2250 m a.s.l. to evaluate the adaptive responses of these species in relation to high-altitude oxidative stresses. The results showed that at higher altitudes, the electrical conductivity and the micronutrient contents of the soil decreased, which may be due to the prevalence of silt and clay decreasing at higher altitudes. Chlorophyll a, chlorophyll b, ascorbic acid, and total soluble protein showed similar results in relation to higher altitudes for all species. On the other hand, proline, total soluble sugars, carotenoids, phenols, tannins, and flavonoids increased in response to high altitudes. The activity levels of catalase and ascorbic acid peroxidase showed a significant increase aligned with higher altitudes, while a significant decrease in activity levels was obtained for polyphenol oxidase. In conclusion, the present findings showed that Cotoneaster orbicularis exhibited the maximum response for coping with high-altitude stresses, followed by the remaining three species regarding the level of biochemical and physiological responses. The present work will help formulate conservation plans for important medicinal species.

Methionine-Induced Regulation of Secondary Metabolites and Antioxidants in Maize (Zea mays L.) Subjected to Salinity Stress

Methionine-Induced Regulation of Secondary Metabolites and Antioxidants in Maize (Zea mays L.) Subjected to Salinity Stress

Dynamic regulation of phenylpropanoid pathway metabolites in modulating sorghum defense against fall armyworm.

Plants undergo dynamic metabolic changes at the cellular level upon insect infestation to better defend themselves. Phenylpropanoids, a hub of secondary plant metabolites, encompass a wide range of compounds that can contribute to insect resistance. Here, the role of sorghum (Sorghum bicolor) phenylpropanoids in providing defense against the chewing herbivore, fall armyworm (FAW), Spodoptera frugiperda, was explored. We screened a panel of nested association mapping (NAM) founder lines against FAW and identified SC1345 and Ajabsido as most resistant and susceptible lines to FAW, respectively, compared to reference parent, RTx430. Gene expression and metabolomic studies suggested that FAW feeding suppressed the expression level of genes involved in monolignol biosynthetic pathway and their associated phenolic intermediates at 10 days post infestation. Further, SC1345 genotype displayed elevated levels of flavonoid compounds after FAW feeding for 10 days, suggesting a diversion of precursors from lignin biosynthesis to the flavonoid pathway. Additionally, bioassays with sorghum lines having altered levels of flavonoids provided genetic evidence that flavonoids are crucial in providing resistance against FAW. Finally, the application of FAW regurgitant elevated the expression of genes associated with the flavonoid pathway in the FAW-resistant SC1345 genotype. Overall, our study indicates that a dynamic regulation of the phenylpropanoid pathway in sorghum plants imparts resistance against FAW.

Molecular Characterization of an Isoflavone 2'-Hydroxylase Gene Revealed Positive Insights into Flavonoid Accumulation and Abiotic Stress Tolerance in Safflower.

Flavonoids with significant therapeutic properties play an essential role in plant growth, development, and adaptation to various environments. The biosynthetic pathway of flavonoids has long been studied in plants; however, its regulatory mechanism in safflower largely remains unclear. Here, we carried out comprehensive genome-wide identification and functional characterization of a putative cytochrome P45081E8 gene encoding an isoflavone 2'-hydroxylase from safflower. A total of 15 CtCYP81E genes were identified from the safflower genome. Phylogenetic classification and conserved topology of CtCYP81E gene structures, protein motifs, and cis-elements elucidated crucial insights into plant growth, development, and stress responses. The diverse expression pattern of CtCYP81E genes in four different flowering stages suggested important clues into the regulation of secondary metabolites. Similarly, the variable expression of CtCYP81E8 during multiple flowering stages further highlighted a strong relationship with metabolite accumulation. Furthermore, the orchestrated link between transcriptional regulation of CtCYP81E8 and flavonoid accumulation was further validated in the yellow- and red-type safflower. The spatiotemporal expression of CtCYP81E8 under methyl jasmonate, polyethylene glycol, light, and dark conditions further highlighted its likely significance in abiotic stress adaption. Moreover, the over-expressed transgenic Arabidopsis lines showed enhanced transcript abundance in OE-13 line with approximately eight-fold increased expression. The upregulation of AtCHS, AtF3'H, and AtDFR genes and the detection of several types of flavonoids in the OE-13 transgenic line also provides crucial insights into the potential role of CtCYP81E8 during flavonoid accumulation. Together, our findings shed light on the fundamental role of CtCYP81E8 encoding a putative isoflavone 2'-hydroxylase via constitutive expression during flavonoid biosynthesis.

A Zebrafish Model of Dnajc21 Deficiency Identifies Essential Roles in Granulocyte Differentiation and Metabolic Regulation

Shwachman-Diamond syndrome (SDS) is a rare inherited bone marrow failure syndrome (IBMFS) characterized by neutropenia and exocrine pancreatic insufficiency. It is caused by mutations in genes required for ribosome subunit maturation such as SBDS, DNAJC21 and EFL1. The cumulative risk of developing myelodysplastic syndrome and/or acute myeloid leukemia for SDS patients is 36% by 30 years of age. As IBMFS are rare and large numbers of primary human samples are not readily available for mechanistic studies, we employed the zebrafish (Danio rerio), given their highly conserved hematopoietic program and ease of genetic manipulation. In contrast to SBDS, no in vivo models of DNAJC21 mutations have been published to date. Using CRISPR-Cas9 genomic editing, we generated mutations in the zebrafish dnajc21 gene. Homozygous mutant larvae recapitulated key features of SDS such as reduced growth and poor neutrophil counts as assessed by Sudan Black staining. Using whole-mount in situ hybridization, we observed reduced l-plastin+ leukocytes with no changes in upstream myb+/cebpa+ hematopoietic stem and progenitor cells and spi1b+ common myeloid progenitors, suggesting a potential differentiation block. In contrast, Dnajc21 loss did not affect erythrocyte specification. Flow cytometry of mutant whole kidney marrows (WKMs, equivalent to human bone marrow) revealed normal numbers of erythrocytes and lymphocytes but reduced myeloid cells accompanied by a trend towards increased progenitors. Further, we found reduced levels of phosphohistone-H3 (pH3) in the mutant larvae, suggesting hypoproliferation. Bulk RNA sequencing of whole larvae at 48 hours post-fertilization identified xenobiotic metabolism, regulation of endopeptidase activity and immune-related processes as key downregulated pathways in the mutants. Upregulated pathways included platelet-derived growth factor receptor signaling, cell adhesion and lysosomal transport. In addition, several genes involved in carbohydrate metabolism such as g6pd, pck1 and ganc were dysregulated. Further, using Oil Red O staining, we observed a reduced accumulation of neutral lipids in the mutants. Leukemic transformation in SDS is driven by the acquisition of mutations in additional genes, including the tumor suppressor, TP53. To model SDS-AML transformation, we crossed the dnajc21 mutants with a zebrafish line carrying a tp53R217H/R217H gain-of-function mutation that confers anti-apoptotic phenotypes. Embryonic pH3+ cell counts were restored and WKM myeloid cells and hematopoietic progenitors were increased in dnajc21-/-/tp53R217H/R217H fish. Finally, using liquid chromatography-mass spectrometry, we show that Dnajc21 is involved in the regulation of certain metabolite and lipid species including hexosyl-ceramides and sphingomyelins, which may contribute to SDS pathophysiology. Our findings suggest that Dnajc21 is required for normal granulocyte differentiation and cell proliferation. We also identified previously unrecognized roles for Dnajc21 in regulating cellular metabolism. We propose that the zebrafish models described here readily serve as in vivo platforms to identify therapeutic compounds that restore normal hematopoiesis and prevent leukemic transformation in SDS.

Anti-depressive-like and cognitive impairment alleviation effects of Gastrodia elata Blume water extract is related to gut microbiome remodeling in ApoE−/− mice exposed to unpredictable chronic mild stress

Ethnopharmacology relevanceGastrodia elata Blume (GE) is a traditional Chinese dietary therapy used to treat neurological disorders. Gastrodia elata Blume water extract (WGE) has been shown to ameliorate inflammation and improve social frustration in mice in a chronic social defeat model. However, studies on the anti-depressive-like effects and cognitive impairment alleviation related to the impact of WGE on the gut microbiome of ApoE−/− mice remain elusive. Aim of the studyThe present study aimed to investigate the anti-depressive-like effect and cognitive impairment alleviation and mechanisms of WGE in ApoE−/− mice subjected to unpredictable chronic mild stress (UCMS), as well as its impact on the gut microbiome of the mice. Materials and methodsSixty ApoE−/− mice (6 months old) were randomly grouped into six groups: control, UCMS, WGE groups [5, 10, 20 mL WGE/kg body weight (bw) + UCMS], and a positive group (fluoxetine 20 mg/kg bw + UCMS). After four weeks of the UCMS paradigm, the sucrose preference, novel object recognition, and open field tests were conducted. The neurotransmitters serotonin (5-HT), dopamine (DA) and their metabolites were measured in the prefrontal cortex. Serum was collected to measure corticosterone and amyloid-42 (Aβ-42) levels. Feces were collected, and the gut microbiome was analyzed. ResultsWGE restored sucrose preference, exploratory behavior, recognition ability, and decreased the levels of serum corticosterone and Aβ-42 in ApoE−/− mice to alleviate depressive-like behavior and cognitive impairment. Furthermore, WGE regulated the monoamine neurotransmitter via reduced the 5-HT and DA turnover rates in the prefrontal cortex. Moreover, WGE elevated the levels of potentially beneficial bacteria such as Bifidobacterium, Akkermansia, Alloprevotella, Defluviitaleaceae_UCG-011, and Bifidobacterium pseudolongum as well as balanced fecal short-chain fatty acids (SCFAs). ConclusionWGE demonstrates anti-depressive-like effects, cognitive impairment alleviation, and gut microbiome and metabolite regulation in ApoE−/− mice. Our results support the possibility of developing a functional and complementary medicine to prevent or alleviate depression and cognitive decline using WGE in CVDs patients.

Transcriptomic and metabolomic investigation of molecular inactivation mechanisms in Escherichia coli triggered by graphene quantum dots

Graphene quantum dots (GQDs), a novel broad-spectrum antibacterial agent, are considered potential candidates in the field of biomedical and food safety due to their outstanding antimicrobial properties and excellent biocompatibility. To uncover the molecular regulatory mechanisms underlying the phenotypes, the overall regulation of genes and metabolites in Escherichia coli (E. coli) after GQDs stimulation was investigated by RNA-sequencing and LC-MS. Gene transcription and metabolite expression related to a series of crucial biomolecular processes were influenced by the GQDs stimulation, including biofilm formation, bacterial secretion system, sulfur metabolism and nitrogen metabolism, etc. This study could provide profound insights into the GQDs stress response in E. coli, which would be useful for the development and application of GQDs in food safety.

Regulation of viable/inactivated/lysed probiotic Lactobacillus plantarum H6 on intestinal microbiota and metabolites in hypercholesterolemic mice

Evidence suggests that probiotic interventions reduce non-communicable diseases (NCDs) risk. However, its therapeutic effect and mechanism are still unclear. To evaluate the hypocholesterolemic effect of Lactobacillus plantarum H6 (L.p H6), a new commercial patent strain capable of preventing hypercholesterolemia, and its mechanism in depth, three states of the strain were prepared, namely, viable (vH6), heat-inactivated (iH6), and ultrasonically-lysed (uH6) bacteria cells. The results showed that v/i/uH6 cells could lower serum and liver blood lipid levels, alleviate liver damage and improve glucose tolerance test (GTT) and insulin tolerance test (ITT) indexes. v/i/uH6 cells improved the gut microbial composition and significantly reduced the Firmicutes to Bacteroidetes ratio (F/B ratio) in feces. In particular, Muribaculaceae may be a potential biomarker for effective cholesterol reduction. Also, the recovery of these biochemical indices and gut microbiome was found following fecal microbiota transplantation (FMT) using stool from vH6 treated mice. The v/i/uH6 cells increased the intestinal flora metabolism of vitamins-cofactors, as well as amino acids, while decreasing the relative content of primary bile acids. The Pearson correlation analysis showed that norank_f__Muribaculaceae and Lactobacillus had a negative correlation with blood lipid levels. Overall, v/i/uH6 cells were effective in improving hypercholesterolemia in mice, and this effect was attributed partly to the regulation of intestinal microbiota and metabolites related to lipid metabolism. Our findings provided a theoretical basis for the industrial development of probiotics and postbiotics and the treatment of cholesterol diseases.

Metabolic and transcriptomic analyses elucidate a novel insight into the network for biosynthesis of carbohydrate and secondary metabolites in the stems of a medicinal orchid Dendrobium nobile

Dendrobium nobile is an important medicinal and nutraceutical herb. Although the ingredients of D. nobile have been identified as polysaccharides, alkaloids, amino acids, flavonoids and bibenzyls, our understanding of the metabolic pathways that regulate the synthesis of these compounds is limited. Here, we used transcriptomic and metabolic analyses to elucidate the genes and metabolites involved in the biosynthesis of carbohydrate and several secondary metabolites in the stems of D. nobile. A total of 1005 metabolites and 31,745 genes were detected in the stems of D. nobile. The majority of these metabolites and genes were involved in the metabolism of carbohydrates (fructose, mannose, glucose, xylulose and starch), while some were involved in the metabolism of secondary metabolites (alkaloids, β-tyrosine, ferulic acid, 4-hydroxybenzoate and chrysin). Our predicted regulatory network indicated that five genes (AROG, PYK, DXS, ACEE and HMGCR) might play vital roles in the transition from carbohydrate to alkaloid synthesis. Correlation analysis identified that six genes (ALDO, PMM, BGLX, EGLC, XYLB and GLGA) were involved in carbohydrate metabolism, and two genes (ADT and CYP73A) were involved in secondary metabolite biosynthesis. Our analyses also indicated that phosphoenol-pyruvate (PEP) was a crucial bridge that connected carbohydrate to alkaloid biosynthesis. The regulatory network between carbohydrate and secondary metabolite biosynthesis established will provide important insights into the regulation of metabolites and biological systems in Dendrobium species.

The albino mechanism of a new theanine-rich tea cultivar 'Fuhuang 2'

To explore the mechanism of tea albino variation and high theanine formation, 'Fuyun 6' and a new theanine-rich tea cultivar 'Fuhuang 2' were as materials in this study, pigment content, metabolome and transcriptome of the two cultivars were analyzed by ultramicroelectron microscopy, widely targeted metabolomics, targeted metabolomics and transcriptomics. The results showed that five catechins, theobromine, caffeine, and 20 free amino acids, including theanine, glutamine, arginine, etc., were identified by targeted metabolomics. The amino acid content of 'Fuhuang 2' was significantly higher than that of 'Fuyun 6', and the theanine content was as high as 57.37 mg/g in 'Fuhuang 2'. The ultrastructure of leaves showed that the chloroplast cell structure of 'Fuhuang 2' was fuzzy, most of the grana lamellae were arranged in disorder, with large gaps, and the thylakoids were filiform. The determination of pigments showed that compared with 'Fuyun 6', the contents of chlorophyll A and B, carotenoids, flavonoids and other pigments of 'Fuhuang 2' decreased significantly, some important pigment-related-genes, such as chlorophyllase (CLH), 9-cis-epoxycarotenoid dioxygenase (NCED), flavonoid 3β-hydroxylase (F3H) and flavonoid 3', 5'-hydroxylase (F3'5'H) were significantly changed. Compared with 'Fuyun 6', 'Fuhuang 2' identified 138 significantly changed metabolites (SCMs) and 658 differentially expressed genes (DEGs). KEGG enrichment analysis showed that SCMs and DEGs were significantly enriched in amino acid biosynthesis, glutathione metabolism and TCA cycle. In general, the albino phenotype of 'Fuhuang 2' may be caused by a deficiency in photosynthetic proteins, chlorophyll metabolism genes and chlorophyll content. The accumulation of high theanine in 'Fuhuang 2' may be due to the low nitrogen consumption in yellowed leaves and the lack of carbon skeleton, amino and nitrogen resources are stored more effectively, resulting in the up regulation of metabolites and related gene expression in the amino acid synthesis pathway, theanine has become a significant accumulation of nitrogen-containing compounds in yellowed leaves.

Effect of Lactobacillus plantarum and Lactobacillus acidophilus fermentation on antioxidant activity and metabolomic profiles of loquat juice

Nonalcoholic fermentation could improve the organoleptic quality and functionality of fruit juice, and lactic acid bacteria (LAB)-fermented fruit juice has been proven to be beneficial to human health. However, LAB exhibit strain specificity with different food matrices. In the present study, the effects of L. plantarum and L. acidophilus on the physicochemical characteristics, antioxidant activity and metabolomics of loquat juices were investigated. Both LAB strains fermentation could significantly enhance the antioxidant activity of loquat juice. L. acidophilus grows faster than L. plantarum in loquat juice, but L. plantarum fermentation more effectively increased the total flavonoid content. Nontargeted metabolomics analysis based on UHPLC-Q Exactive HF-X/MS were performed to reveal the different metabolic profiles between LAB fermentation. A total of 776 metabolites were identified and annotated. The significant differentially regulated metabolites were concentrated mainly in lipids and lipid-like molecules; organic acids and derivatives; amino acids, peptides, and analogs; phenolic compounds and terpenoids. The regulation of metabolites plays a very important role in the flavor reconstruction and functional improvement of loquat juices. In addition, the metabolic profiles between L. plantarum- and L. acidophilus-fermented loquat juices were different, and the application of cofermentation of these two strains may be considered in future studies.

Mechanisms of Ardisia japonica in the Treatment of Hepatic Injury in Rats Based on LC-MS Metabolomics.

The mechanism of action of Ardisia japonica in the treatment of immune liver injury was systematically analyzed from the perspective of the biological metabolic network by using non-targeted metabolomics combined with biological network analysis tools. A rat model of acute immune hepatic injury was established by Concanavalin A (Con A) and the efficacy of the treatment of acute immune liver injury was judged by gavage of A. japonica. Liquid chromatography-mass spectrometry (LC-MS)-based plasma metabolomics was used to identify the key metabolites and metabolic pathways for the hepatoprotective effects of A. japonica. The results demonstrated that A. japonica reduced the levels of inflammatory parameters, decreased hepatic malondialdehyde levels, and enhanced hepatic antioxidant enzyme activity in animal experiments. The clustering of metabolomic samples showed significant separation in principal component analysis plots and the three groups in PLS-DA and OPLS-DA models could be clearly distinguished in multivariate statistical analysis. Among the 937 total metabolites, 445 metabolites were significantly different between the control and model groups, while 144 metabolites were identified as metabolites with differences between the model and administration groups, and a total of 39 differential metabolites were identified to affect the metabolic levels of the three groups. The differential metabolites were principally involved in the citric acid cycle, glutathione metabolism, vitamin B6 metabolism, and steroid hormone biosynthesis. This study found that A. japonica can significantly inhibit acute liver injury in rats, and exert a hepatoprotective effect through anti-inflammatory effect, inhibition of lipid peroxidation, improvement of the antioxidant defense system, and regulation of metabolites and related metabolic pathways. This study will provide a theoretical basis for the application of A. japonica in the treatment of the liver injury.