Indole Production Research Articles

Microbiota protect the kidneys

Microbiota Chronic kidney disease (CKD) afflicts millions of people globally. The first-line treatment for CKD is dietary intervention, so there may be a gut microbiota–associated component. Lobel et al. investigated the mechanistic links between the microbiota and protein intake, because the protein metabolites indole and indoxyl sulfate are known uremic toxins (see the Perspective by Pluznick). The authors used a mouse model of CKD precipitated by a paucity of the dietary sulfur–containing amino acids methionine and cysteine. Bacterial metabolism of sulfur-containing amino acids modulated indole production by sulfide inhibition of the enzyme tryptophanase, thus abrogating uremic toxicity by this metabolite in this model system. Science , this issue p. [1518][1]; see also p. [1426][2] [1]: /lookup/doi/10.1126/science.abb3763 [2]: /lookup/doi/10.1126/science.abd8344

Lemon Exosome-like Nanoparticles-Manipulated Probiotics Protect Mice from C.d iff Infection.

SummaryClostridioides difficile (C. diff) is the leading cause of antibiotic-associated colitis. Here, we report that lemon exosome-like nanoparticles (LELNs) manipulated probiotics to inhibit C. diff infection (CDI). LELN-manipulated Lactobacillus rhamnosus GG (LGG) and Streptococcus thermophilus ST-21 (STH) (LELN-LS) decrease CDI mortality via an LELN-mediated increase in bile resistance and gut survivability. LELN-LS treatment increases the AhR ligands indole-3-lactic acid (I3LA) and indole-3-carboxaldehyde (I3Ald), leading to induction of IL-22, and increases lactic acid leading to a decrease of C. diff fecal shedding by inhibiting C. diff growth and indole biosynthesis. A synergistic effect between STH and LGG was identified. The STH metabolites inhibit gluconeogenesis of LGG and allow fructose-1,6-bisphosphate (FBP) to accumulate in LGG; accumulated FBP then activates lactate dehydrogenase of LGG (LGG-LDH) and enhances production of lactic acid and the AhR ligand. Our findings provide a new strategy for CDI prevention and treatment with a new type of prebiotics.

Rhizobacterial biofilm and plant growth promoting trait enhancement by organic acids and sugars

In the study,Pseudomonas sp. K6 and Pseudomonas monteilii were found to form an enhanced biofilm when cultured in the presence of organic acids and sugars. Here, the highest biofilm could be observed for Pseudomonas sp. K6 (3.08 ± 0.13) and P. monteilii (1.99 ± 0.12) when cultured in presence of 10 µM malic acid. However, maximum production of indole 3 acetic acid (IAA) was observed with 25 µM succinic acid treatment for Pseudomonas sp. K6 (24.33 ± 0.57 µg ml−1) and with 25 µM galactose for P. monteilii (20 ± 0.0 µg ml−1). At the same time, Pseudomonas sp. K6 solubilized the highest quantity of phosphate in the presence of 50 µM citric acid (21.33 ± 0.0 µM) and P. monteilii was observed to produce 32.66 ± 1.25 µM soluble phosphate in the presence of 10 µM galactose. The results of the study demonstrate the role of organic acids and sugars in the enhancement of biofilm formation, IAA production and phosphate solubilization in selected Pseudomonas spp. and highlight the potential use of rhizobacteria in conjugation with supplement for the agricultural applications.

From intestinal dysbiosis to alcohol-associated liver disease.

Alcohol-associated intestinal dysbiosis and bacterial overgrowth can lead to a dysregulation of tryptophan metabolism and lower production of indoles. Several of these indole derivatives are aryl hydrocarbon receptor ligands that, in turn, are involved in antimicrobial defense via induction of interleukin-22 (IL-22). IL-22 increases the expression of intestinal regenerating islet-derived 3 (Reg3) lectins, which maintain low bacterial colonization of the inner mucus layer and reduce bacterial translocation to the liver. Chronic alcohol consumption is associated with reduced intestinal expression of Reg3β and Reg3γ, increased numbers of mucosa-associated bacteria and bacterial translocation. Translocated microbial products and viable bacteria reach the liver and activate the innate immune system. Release of inflammatory molecules promotes inflammation, contributes to hepatocyte death and results in a fibrotic response. This review summarizes the mechanisms by which chronic alcohol intake changes the gut microbiota and contributes to alcohol-associated liver disease by changing microbial-derived metabolites.

Coal-Degrading Bacteria Display Characteristics Typical of Plant Growth Promoting Rhizobacteria

Coal mining produces large quantities of discard that is stockpiled in large dumps. This stockpiled material, termed coal discard, poses an environmental threat emphasising the need for appropriate bioremediation. Here, metagenomic analysis of the 16S rRNA from ten coal-degrading strains previously isolated from coal slurry from discard dumps and from the rhizosphere of diesel-contaminated sites was used to establish genetic relatedness to known plant growth-promoting (PGP) bacteria in the NCBI database. Measurement of indole and ammonium production and solubilisation of P and K were used to screen bacteria for PGP characteristics. BLAST analysis revealed ≥ 99% homology of six isolates with reference PGP strains of Bacillus, Escherichia, Citrobacter, Serratia, Exiguobacterium and Microbacterium, while two strains showed 94% and 91% homology with Proteus. The most competent PGP strains were Proteus strain ECCN 20b, Proteus strain ECCN 23b and Serratia strain ECCN 24b isolated from diesel-contaminated soil. In response to L-trp supplementation, the concentration of indolic compounds (measured as indole-3-acetic acid) increased. Production of ammonium and solubilisation of insoluble P by these strains was also apparent. Only Serratia strain ECCN 24b was capable of solubilising insoluble K. Production of indoles increased following exposure to increasing aliquots of coal discard, suggesting no negative effect of this material on indole production by these coal-degrading bacterial isolates and that these bacteria may indeed possess PGP characteristics.

Mechanism and Origins of Product Selectivity of Au‐Catalyzed Coupling Benzisoxazoles with Ynamides: A Computational Study

AbstractAu(I)‐catalyzed coupling of benzisoxazoles and ynamides was recently reported to synthesize challenging indoloquinoline core structures. In this report, we employed DFT methods to elucidate the mechanistic details of this reaction. The results reveal that the catalytic cycle involves initial coupling of ynamide with benzisoxazole, simultaneous ring opening of the isoxazole unit and attack of the dimethoxybenzene (DMOB) unit to gold carbenoid, proton transfer from the DMOB group to hydroxyl group, thioether migration, ring closure, and proton transfer. The experimentally observed ligand‐controlled product selectivity is reproduced well by the calculations. The product selectivity‐determining step is the ring opening of the isoxazole unit. The flexible P(t‐Bu)2(o‐biphenyl) ligand facilitates the approach of the DMOB group to gold carbenoid, which brings about significant C−H/π interactions in the transition state for ring opening, and thus leads to the indoloquinoline product. The rigid 1,3‐bis(diisopropylphenyl)imidazol‐2‐ylidene ligand prefers keeping the DMOB group away from the gold carbenoid, which can cause strong orbital interaction in the transition state for ring opening, and thus results in indole product.

Effects of tryptophan and probiotic supplementation on growth and behavior in quail

In laying hens, a diet supplemented with tryptophan (Trp) has been shown to affect their pecking behavior. However, unlike this positive effect, Trp is also involved in negative effects on behavior and stress through indolic pathways. Indole production can be reduced by probiotics (Pro), thus we hypothesized that Pro may prevent negative effects of Trp and increase beneficial effects on behavior in birds. Combined effects of Pro and Trp were also expected. To investigate the effects on behavior in birds of supplementing with a high level of Trp with or without Pro, Japanese quail were used because their behavior can be influenced by Pediococcus acidilactici, and they can be highly aggressive. Quails (n = 120) were assigned to 4 groups in a 2 × 2 factorial design for 55 d: C-C (control diet with usual Trp level, 0.3%; without Pro; n = 30), Trp-C (Trp: 2%; without Pro; n = 30), C-Pro (control diet; with Pro: 1 x 109 CFU/L P. acidilactici in drinking water; n = 30), and Trp-Pro (Trp 2%; with Pro; n = 30). Body weight was measured every week, and different tests were conducted to investigate behavioral characteristics of each quail. Contrary to our hypothesis, there was almost no interaction between Trp and Pro treatments. Tryptophan supplementation significantly (P < 0.05) reduced live weight up to 27 d, whereas Pro treatment had no effect. There was no significant difference between groups for tonic immobility variables (P > 0.05). The birds fed the high Trp diet spent significantly less time in the periphery of the open field than those fed the control diet and moved less in the arena during the social isolation test. Interindividual distances were significantly lower in males fed with Trp 2% than with the control diet, whereas Trp and Pro supplements interacted in females. The treatments did not affect sexual motivation in males. These results indicate that a high level of Trp reduced growth and appeared to enhance emotional reactivity in quails and that supplementing with Pro did not reduce these effects. In conclusion, feeding high Trp for 55 d cannot be recommended as a strategy to improve social behavior unlike effects observed in laying hens.

Experimental investigation into indole production using passaging of E. coli and B. subtilis along with unstructured modeling and parameter estimation using dynamic optimization: An integrated framework

Greener process synthesis for drug production focuses on the replacement of chemical processes with biological processes. However, optimization of these processes remains challenging due to lack of experimental data, particularly for long term passaging and suitable parameter estimation techniques. In this context, we propose a mixed passaging scheme containing the co-culture of E. coli and B. subtilis that can be used to produce indole. The cell growth and product profiles obtained from fermenter corresponding to pure culture and individual culture obtained after passaging of E. coli and B. subtilis were used for unstructured model selection. Kinetic parameter estimation was performed using a hybrid technique combining classical and evolutionary algorithms. The dynamic interaction between the two organisms in long term passaging was captured by implementing optimal control for estimating time-varying parameters. The proposed unstructured model is capable of emulating the mixed culture effect on cell growth, product formation, and substrate depletion. This is the first instance where an integrated framework combining experimental and computational methodology is used to estimate and analyse model parameters in a mixed culture of E. coli and B. subtilis towards indole production. A similar framework can be used for optimizing the process parameters to improve the indole production.

Inhibition of indole production increases the activity of quinolone antibiotics against E. coli persisters

Persisters are a sub-population of genetically sensitive bacteria that survive antibiotic treatment by entering a dormant state. The emergence of persisters from dormancy after antibiotic withdrawal leads to recurrent infection. Indole is an aromatic molecule with diverse signalling roles, including a role in persister formation. Here we demonstrate that indole stimulates the formation of Escherichia coli persisters against quinolone antibiotics which target the GyrA subunit of DNA gyrase. However, indole has no effect on the formation of E. coli persisters against an aminocoumarin, novobiocin, which targets the GyrB subunit of DNA gyrase. Two modes of indole signalling have been described: persistent and pulse. The latter refers to the brief but intense elevation of intracellular indole during stationary phase entry. We show that the stimulation of quinolone persisters is due to indole pulse, rather than persistent, signalling. In silico docking of indole on DNA gyrase predicts that indole docks perfectly to the ATP binding site of the GyrB subunit. We propose that the inhibition of indole production offers a potential route to enhance the activity of quinolones against E. coli persisters.

Agricultural Utilization of Unused Resources: Liquid Food Waste Material as a New Source of Plant Growth-Promoting Microbes

Organic amendment is important for promoting soil quality through increasing soil fertility and soil microbes. This study evaluated the effectiveness of using liquid food waste material (LFM) as a microbial resource, by analyzing the microbial community composition in LFM, and by isolating plant growth-promoting bacteria (PGPB) from the material. High-throughput sequencing of LFM, collected every month from May to September 2018, resulted in the detection of &gt;1000 bacterial operational taxonomic units (OTUs) in the LFM. The results showed that Firmicutes was abundant and most frequently detected, followed by Proteobacteria and Actinobacteria. Of the culturable strains isolated from LFM, almost all belonged to the genus Bacillus. Four strains of PGPB were selected from the isolated strains, with traits such as indole acetic acid production and 1-aminocyclopropane-1-carboxylic acid deaminase activity. Lettuce growth was improved via LFM amendment with PGPB, and Brassica rapa showed significant differences in root biomass when LFM amendment was compared with the use chemical fertilizer. Field experiments using LFM showed slight differences in growth for Brassica rapa, lettuce and eggplant, when compared with the use of chemical fertilizer. LFM is a useful microbial resource for the isolation of PGPB, and its use as fertilizer could result in reduced chemical fertilizer usage in sustainable agriculture.

Isolation of Plant Growth Promoting Bacteria from the Rhizosphere of Different Plants and Assessment of Their Plant Growth Promotion Potential

Plant are benefitted in different aspects by symbiotic bacteria. Environmental conditions, Plantconditions and type of pathogens determine these important services for plants Objective: Theresearch was conducted to assess the plant growth enhancing effects of wheat and cabbagerhizobacteria on the growth of wheat plant Methods: For this purpose, total 49 bacteria were isolatedand characterized from the rhizosphere of wheat and cabbage plants. The isolates were assessed forplant growth promoting properties such as: indole acetic acid production, phosphate solubilization,antibacterial activity and heavy metal resistance. Indole acetic acid was found to be produced by 7isolates and phosphate solubilization was shown by 20 isolates. Antibacterial activity was determinedagainst four clinical isolates like Staphylococcus aureus, Klebsiella sp., Escherichia coli and Pseudomonasaeruginosa Results: Antibacterial activity against Staphylococcus aureus was shown by 38 isolates, 12isolates showed antibacterial activity against Escherichia coli and Klebsiella sp., whereas no isolate wasfound to be positive against Pseudomonas aeruginosa. Another plant growth enhancing trait (heavymetal resistance) was shown by 28 rhizobacteria. In order to evaluate the capability of isolates toenhance the plant growth, bio-inoculation assay was performed using wheat seeds Conclusions:Rhizobacterial inoculation increased the number of roots, shoots, leaves and roots and shoot length ofwheat plantlets as compared to un-inoculated control.

Isolation and Characterization of &lt;i&gt;Escherichia albertii&lt;/i&gt; from Environmental Water in Akita Prefecture, Japan

Escherichia albertii is a newly emerging food-borne pathogen. However, infection routes to patients remain unclear. In the present study, we aimed to isolate and characterize E. albertii from environmental water in Akita Prefecture of Japan. E. albertii was detected in 16 of 52 samples by real-time polymerase chain reaction analysis, and a total of 13 E. albertii strains were isolated from 9 samples. None of isolates showed the properties of biogroup 1 or 2 described previously on indole production and lysine decarboxylase activity. Susceptibility testing against 11 antimicrobial agents showed that one isolate was resistant only to ampicillin (7.7%). All isolates were positive for eae and cdt as virulence genes, but were negative for stx, including stx2f. Pulsed-field gel electrophoresis analysis showed that E. albertii isolates were genetically heterogeneous, but two isolates from environmental water had the similarity of >80% to some E. albertii strains from humans. These results suggest that E. albertii derived from environmental water has the potential to infect humans.

Depressive symptoms, fruit and vegetables consumption and urinary 3-indoxylsulfate concentration: a nested case-control study in the French Nutrinet-Sante cohort.

Previous epidemiologic studies have provided some evidence of an inverse association between fruit and vegetables consumption and risk of developing recurrent depressive symptoms. This association could possibly be explained by the role of such dietary factors on the gut microbiota. Especially, indole, a metabolite of tryptophan produced by gut bacteria, may be associated with the development of mood disorders. Thus, the purpose of this study was to investigate relationships between fruit and vegetables intake, recurrent depressive symptoms and indole, using measurement of its main urinary excretion form, i.e., 3-indoxylsulfate, as a biomarker. A nested case-control study was conducted in 891 women (aged 45-65) participating to the web-based NutriNet-Santé cohort with available dietary data and biological samples. Cases (individuals with recurrent depressive symptoms, n = 297) were defined as having two Center for Epidemiologic Studies-Depression Scale (CES-D) scores ≥ 16 during the follow-up and were matched with 2 controls having two CES-D scores < 16. Urinary 3-indoxylsulfate concentration was measured as a biomarker of indole production by the gut microbiota. Multivariable conditional logistic regression models were used to test the association of both fruit and vegetables consumption and urine 3-indoxylsulfate measurements with recurrent depressive symptoms. We also tested the association between fruit and vegetables consumption and urinary 3-indoxylsulfate levels using multivariate analysis of variance models. We found a significant inverse association between fruit and vegetables consumption and the risk of having recurrent depressive symptoms over a 2-year period. Fruit and vegetables consumption was inversely associated to urinary 3-indoxylsulfate concentration. However, no significant association was observed between urinary 3-indoxylsulfate levels and recurrent depressive symptoms within this sample. Our results confirm that low fruit and vegetables consumption could be associated with recurrent depressive symptoms. We also found an inverse association between fruit and vegetable intake and urinary levels of 3-indoxylsulfate. However, it is not possible to conclude to a possible mediation role of the indole produced by the gut microbiota from tryptophan, since there was no relationship between 3-indoxylsulfate and recurrent depressive symptoms.

Dietary Fiber from Oat and Rye Brans Ameliorate Western Diet-Induced Body Weight Gain and Hepatic Inflammation by the Modulation of Short-Chain Fatty Acids, Bile Acids, and Tryptophan Metabolism.

Dietary fiber (DF) induces changes in gut microbiota function and thus modulates the gut environment. How this modulation is associated with metabolic pathways related to the gut is largely unclear. This study aims to investigate differences in metabolites produced by the gut microbiota and their interactions with host metabolism in response to supplementation with two bran fibers. Male C57BL/6N mice are fed a western diet (WD) for 17 weeks. Two groups of mice received a diet enriched with 10% w/w of either oat or rye bran, with each bran containing 50% DF. Microbial metabolites are assessed by measuring cecal short-chain fatty acids (SCFAs), ileal and fecal bile acids (BAs), and the expression of genes related to tryptophan (TRP) metabolism. Both brans lowered body weight gain and ameliorated WD-induced impaired glucose responses, hepatic inflammation, liver enzymes, and gut integrity markers associated with SCFA production, altered BA metabolism, and TRP diversion from the serotonin synthesis pathway to microbial indole production. Both brans develop a favorable environment in the gut by altering the composition of microbes and modulating produced metabolites. Changes induced in the gut environment by a fiber-enriched diet may explain the amelioration of metabolic disturbances related to WD.

Volatile emission compounds from plant growth-promoting bacteria are responsible for the antifungal activity against F. solani.

The aims of this work were to screen isolated bacteria with a dual capacity: to inhibit Fusarium solani and to promote plant growth. Also, volatile compounds that would be responsible for that effect were identified. Seventy bacterial strains from the air, agricultural soils, hydrocarbons-contaminated soils, and extremophile soils were tested. The former were identified by Matrix-Assisted Laser Desorption/Ionization-time of flight mass spectrometry and 16S rDNA sequencing. The plant growth-promoting bacteria (PGPB) and their capability for phosphate solubilization, siderophores production, and indole production were determined. Twenty isolates from Bacillus and Pseudomonas genera inhibited the mycelial growth up to 40% in direct assays. Eleven isolates significantly inhibited mycelial growth in 18-24% via volatile emissions. Volatile compounds related to antifungal activity or stress response include ketones, sesquiterpenes, monoterpenoids, alkanes, and fatty acids. Our results support the potential of these PGPB to act as biocontrol agents against fungal pathogens via volatile emissions.

The gut microbiota metabolite indole increases emotional responses and adrenal medulla activity in chronically stressed male mice

Background and aimsThe gut microbiota produces metabolites that are an integral part of the metabolome and, as such, of the host physiology. Changes in gut microbiota metabolism could therefore contribute to pathophysiological processes. We showed previously that a chronic and moderate overproduction of indole from tryptophan in male individuals of the highly stress-sensitive F344 rat strain induced anxiety-like and helplessness behaviors. The aim of the present study was to extend the scope of these findings by investigating whether emotional behaviors of male mice that are moderately stress-sensitive but chronically exposed to environmental stressors would also be affected by indole. MethodsWe colonized germ-free male C3H/HeN mice with a wild-type indole-producing Escherichia coli strain, or with the non-indole producing mutant. Gnotobiotic mice were subjected to an unpredictable chronic mild stress procedure, then to a set of tests aimed at assessing anxiety-like (novelty and elevated plus maze tests) and depression-like behaviors (coat state, splash, nesting, tail suspension and sucrose tests). Results of the individual tests were aggregated into a common z-score to estimate the overall emotional response to chronic mild stress and chronic indole production. We also carried out biochemical and molecular analyses in gut mucosa, plasma, brain hippocampus and striatum, and adrenal glands, to examine biological correlates that are usually associated with stress, anxiety and depression. ResultsChronic mild stress caused coat state degradation and anhedonia in both indole-producing and non-indole producing mice, but it did not influence behaviors in the other tests. Chronic indole production did not influence mice behavior when tests were considered individually, but it increased the overall emotionality z-score, specifically in mice under chronic mild stress. Interestingly, in the same mice, indole induced a dramatic increase of the expression of the adrenomedullary Pnmt gene, which is involved in catecholamine biosynthesis. By contrast, systemic tryptophan bioavailability, brain serotonin and dopamine levels and turnover, as well as expression of gut and brain genes involved in cytokine production and tryptophan metabolism along the serotonin and kynurenine pathways, remained similar in all mice. ConclusionsChronic indole production by the gut microbiota increased the vulnerability of male mice to the adverse effects of chronic mild stress on emotional behaviors. It also targeted catecholamine biosynthetic pathway of the adrenal medulla, which plays a pivotal role in body’s physiological adaptation to stressful events. Future studies will aim to investigate the action mechanisms responsible for these effects.

High-Meat-Protein High-Fat Diet Induced Dysbiosis of Gut Microbiota and Tryptophan Metabolism in Wistar Rats.

Meat-diet-induced changes in gut microbiota are often accompanied with the development of various metabolic and inflammatory disorders. The exact biochemical mechanism underlying these effects is not well elucidated. This study aims to evaluate how meat proteins in high-fat diets affect tryptophan metabolism in rats. The high-chicken-protein (HFHCH) or high-pork-protein (HFHP) diets increased levels of skatole and indole in cecal and colonic contents, feces, and subcutaneous adipose tissue. The HFHCH and HFHP diets also increased the abundance of Lactobacillus, the Family XIII AD3011 group, and Desulfovibrio in the cecum and colon, which may be involved in the production of skatole and indole. Additionally, high-meat-protein diets induced lower activity of skatole- and indole-metabolizing enzyme CYP2E1 in liver compared with low-meat-protein diets. This work highlights the negative impact of high meat proteins on physiological responses by inducing dysbiosis of gut microbiota and tryptophan metabolism.

Glaesserella australis sp. nov., isolated from the lungs of pigs

Twenty-nine isolates of an unknown haemophilic organism were isolated from the lungs of pigs from 14 farms in Australia. Phylogenetic analyses based on the 16S rRNA gene, recN and rpoA showed a monophyletic group that was most closely related to Glaesserella parasuis and [Actinobacillus] indolicus. Whole genome sequence analysis indicated that the Glaesserella parasuis and this group, using the type strain HS4635T for comparison, showed a similarity of 30.9 % DNA-DNA renaturation. The isolates were Gram-stain-negative, NAD-dependent, CAMP-negative and were oxidase-positive, catalase-negative and produced indole but not urease. The isolates could be separated from all currently recognized haemophilic and non-haemophilic members of the family Pastuerellaceae. Key phenotypic properties were the production of indole, the lack of urease activity, production of β-galactosidase but not α-fucosidase, acid formation from (-)-d-arabinose, (+)-d-galactose, maltose and trehalose and a failure to produce acid from (-)-d-mannitol. Taken together, these data indicate that the isolates belong to a novel species for which the name Glaesserella australis sp. nov. is proposed. The type strain is HS4635T (=CCUG 71931T and LMG 30645T).

Promoción de crecimiento en trigo (Triticum turgidum L. subsp. durum) por la co-inoculación de cepas nativas de Bacillus aisladas del Valle del Yaqui, México

Introducción: Las rizobacterias promotoras del crecimiento vegetal (RPCV) son un grupo de bacterias rizosféricas con la habilidad de promover el crecimiento y la salud de las plantas, y restaurar la fertilidad del suelo. El presente estudio tuvo como objetivo evaluar la promoción del crecimiento en el cultivo de trigo (Triticum turgidum L. subsp. durum) por la co-inoculación de cepas nativas del género Bacillus aisladas del Valle del Yaqui, México, para su potencial uso como inoculante microbiano.Método: Tres cepas bacterias obtenidas de la Colección de Microorganismos Edáficos y Endófitos Nativos (COLMENA), aisladas del cultivo de trigo en el Valle del Yaqui, fueron estudiadas. Primeramente, se realizó la identificación molecular de las cepas mediante la secuenciación del gen 16S RNAr, mediante la plataforma Sanger. Además, las cepas bacterianas fueron caracterizadas metabólicamente mediante actividades funcionales asociadas a la promoción del crecimiento vegetal (producción de indoles, solubilización de fósforo insoluble, y producción de sideróforos). Finalmente, el impacto de la inoculación de estas cepas individualmente, y en consorcios fue determinado utilizando el cultivo de trigo (Triticum turgidum L subsp. durum) como planta modelo, simulando las condiciones edafo-climáticas del Valle del Yaqui. Las variables morfométricas medidas fueron la longitud aérea y de raíz, peso seco aéreo y de raíz, e índice de biovolumen.Resultados: Las cepas TRQ8, TRQ65 y TE3T fueron afiliadas taxonómicamente a Bacillus megaterium, Bacillus paralicheniformis y Bacillus cabrialesii, respectivamente; dicha clasificación fue soportada por sus características macro-microscópica como: su forma bacilar y tinción Gram positiva, que son características propias de este género bacteriano. Las cepas en estudio tuvieron la capacidad de producir indoles, siendo B. paralicheniformis TRQ65 quien presentó mayor producción con 39.29 µg/mL. Mientras que en la prueba de solubilización de fósforo insoluble las 3 cepas mostraron la capacidad en un rango de índice de solubilización de 1.37 a 1.43; finalmente, solamente la cepa B. megaterium TRQ8 mostró un índice de producción de sideróforos de 8.17. La inoculación del consorcio B. megaterium TRQ8 + B. paralicheniformis TRQ65 mostró los mayores incrementos en las 5 variables medidas en la planta, diferencia significativa (p&lt;0.05) vs. el tratamiento no inoculado, la longitud aérea y radical mostró un incremento de 6 y 10% respectivamente, mientras que la biomasa seca aérea aumentó 60% y la biomasa seca radicular se incrementó en 82%. El índice de biovolumen se incrementó en 18% por la inoculación de dicho consorcio bacteriano.Discusión o Conclusión: Las cepas estudiadas presentan características de promoción de crecimiento in vitro e in vivo. Sin embargo, la co-inoculación de B. megaterium TRQ8 y B. paralicheniformis TRQ65 incrementó su capacidad de promoción del crecimiento en plantas de trigo. Por lo cual, los mecanismos asociados a dicho efecto, así como sus funciones ecológicas e interacción con los factores bióticos y abióticos de los agro-sistemas deben ser estudiadas para su validación en diferentes agroecosistemas, antes de su utilización extensiva como un inoculante microbiano.

Inulin-type fructan intervention restricts the increase in gut microbiome–generated indole in patients with peritoneal dialysis: a randomized crossover study

Indoxyl sulfate (IS) and p-cresyl sulfate (pCS), 2 important protein-bound uremic toxins, are independent risk factors for cardiovascular disease in patients with end-stage renal disease. Indole and p-cresol are gut microbiome-generated precursors of IS and pCS. The aim of the present study was to determine whether inulin-type fructans (ITFs) reduce the production of indole and p-cresol by altering their producing bacteria in patients with peritoneal dialysis. Patients receiving peritoneal dialysis for >3 mo without diabetes and not using antibiotics were recruited to a randomized, double-blind, placebo-controlled, crossover trial of ITF intervention over 36 wk (12-wk washout). The primary outcomes were gut microbiome, fecal indole and p-cresol, indole-producing bacteria, p-cresol-producing bacteria, and serum IS and pCS. The secondary outcomes were fecal pH, 24-hurine, and dialysis removal of IS and pCS. Of 21 individuals randomly assigned, 15 completed the study. The daily nutrient intakes, including protein, tryptophan, and tyrosine, were isostatic during the prebiotic, washout, and placebo intervention. There were no baseline differences in the outcomes of interest between treatments. For fecal indole, its concentrations did not change significantly in either treatment. However, there was a trend toward the treatment-by-time effect (P=0.052), with a quantitative reduction in the ITF treatment and an increase in the control. The difference in the changes between the 2 treatments was significant (-10.07±7.48 μg/g vs +13.35±7.66 μg/g; P=0.040). Similar to Bacteroides thetaiotaomicron, there was a difference over time between the 2 treatments, with a significant treatment and time interaction effect (P=0.047). There were no treatment, time, or interaction effects for fecal p-cresol, serum IS and pCS, 24-hurine, and dialysis removal of IS and pCS. Our results suggested that ITFs restricted the increase in gut microbiome-generated indole in patients with peritoneal dialysis. This trial was registered at http://www.chictr.org.cn/showproj.aspx?proj=21228 as ChiCTR-INR-17013739.