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Ruminal microbe of biohydrogenation of trans-vaccenic acid to stearic acid in vitro.

ABSTRACT: Optimization of the unsaturated fatty acid composition of ruminant milk and meat is desirable. Alteration of the milk and fatty acid profile was previously attempted by the management of ruminal microbial biohydrogenation. The aim of this study was to identify the group of ruminal trans-vaccenic acid (trans-11 C18:1, t-VA) hydrogenating bacteria by combining enrichment studies in vitro.The enrichment culture growing on t-VA was obtained by successive transfers in medium containing t-VA. Fatty acids were detected by gas chromatograph and changes in the microbial composition during enrichment were analyzed by denaturing gradient gel electrophoresis (DGGE). Prominent DGGE bands of the enrichment cultures were identified by 16S rRNA gene sequencing.The growth of ruminal t-VA hydrogenating bacteria was monitored through the process of culture transfer according to the accumulation of stearic acid (C18:0, SA) and ratio of the substrate (t-VA) transformed to the product (SA). A significant part of the retrieved 16S rRNA gene sequences was most similar to those of uncultured bacteria. Bacteria corresponding to predominant DGGE bands in t-VA enrichment cultures clustered with t-VA biohydrogenated bacteria within Group B.This study provides more insight into the pathway of biohydrogenation. It also may be important to control the production of t-VA, which has metabolic and physiological benefits, through management of ruminal biohydrogenation bacterium.

SUBMITTER: Li D

PROVIDER: S-EPMC3305423 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Ruminal microbe of biohydrogenation of trans-vaccenic acid to stearic acid in vitro.

Li Dan D Wang Jia Qi JQ Bu Deng Pan DP

BMC research notes 20120215

<h4>Background</h4>Optimization of the unsaturated fatty acid composition of ruminant milk and meat is desirable. Alteration of the milk and fatty acid profile was previously attempted by the management of ruminal microbial biohydrogenation. The aim of this study was to identify the group of ruminal trans-vaccenic acid (trans-11 C18:1, t-VA) hydrogenating bacteria by combining enrichment studies in vitro.<h4>Methods</h4>The enrichment culture growing on t-VA was obtained by successive transfers ...[more]

PMID: 22336099

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Project description:Cistus ladanifer (rockrose) is a perennial shrub quite abundant in the Mediterranean region, and it is a rich source in secondary compounds such as condensed tannins (CTs). Condensed tannins from C. ladanifer were able to change the ruminal biohydrogenation (BH), increasing the t11-18:1 and c9,t11-18:2 production. However, the adequate conditions of the C. ladanifer CTs used to optimize the production of t11-18:1 and c9,t11-18:2 is not yet known. Thus, we tested the effect of increasing the doses of C. ladanifer CT extract (0, 25, 50, 75 and 100 g/kg dry matter (DM)) on in vitro rumen BH. Five in vitro batch incubations replicates were conducted using an oil supplemented high-concentrate substrate, incubated for 24 h with 6 mL of buffered ruminal fluid. Volatile fatty acids (VFAs) and long chain fatty acids (FA) were analyzed at 0 h and 24 h, and BH of c9-18:1, c9, c12-18:2 and c9, c12, c15-18:3, and BH products yield were computed. Increasing doses of C. ladanifer CTs led to a moderate linear decrease (p < 0.001) of the VFA production (a reduction of 27% with the highest dose compared to control). The disappearance of c9-18:1 and c9,c12-18:2 as well as the production of t11-18:1 and c9, t11:18:2 was not affected by increasing doses of C. ladanifer CTs, and only the disappearance of c9, c12, c15-18:3 suffered a mild linear decrease (a reduction of 24% with the highest dose compared to control). Nevertheless, increasing the C. ladanifer CT dose led to a strong depression of microbial odd and branched fatty acids and of dimethyl acetals production (less than 65% with the highest dose compared to control), which indicates that microbial growth was more inhibited than fermentative and biohydrogenation activities, in a possible adaptative response of microbial population to stress induced to CTs and polyunsaturated fatty acids. The ability of C. ladanifer to modulate the ruminal BH was not verified in the current in vitro experimental conditions, emphasizing the inconsistent BH response to CTs and highlighting the need to continue seeking the optimal conditions for using CTs to improve the fatty acid profile of ruminant fat.

Project description:BackgroundColorectal cancer is the third largest cause of cancer-related mortality worldwide. Although current treatments with chemotherapeutics have allowed for management of colorectal cancer, additional novel treatments are essential. Intervening with the metabolic reprogramming observed in cancers called "Warburg Effect," is one of the novel strategies considered to combat cancers. In the metabolic reprogramming pathway, pyruvate dehydrogenase kinase (PDK1) plays a pivotal role. Identification and characterization of a PDK1 inhibitor is of paramount importance. Further, for efficacious treatment of colorectal cancers, combinatorial regimens are essential. To this end, we opted to identify a PDK1 inhibitor using computational structure-based drug design FINDSITEcomb and perform combinatorial studies with 5-FU for efficacious treatment of colorectal cancers.MethodsUsing computational structure-based drug design FINDSITEcomb, stearic acid (SA) was identified as a possible PDK1 inhibitor. Elucidation of the mechanism of action of SA was performed using flow cytometry, clonogenic assays.ResultsWhen the growth inhibitory potential of SA was tested on colorectal adenocarcinoma (DLD-1) cells, a 50% inhibitory concentration (IC50) of 60 µM was recorded. Moreover, SA inhibited the proliferation potential of DLD-1 cells as shown by the clonogenic assay and there was a sustained response even after withdrawal of the compound. Elucidation of the mechanism of action revealed, that the inhibitory effect of SA was through the programmed cell death pathway. There was increase in the number of apoptotic and multicaspase positive cells. SA also impacted the levels of the cell survival protein Bcl-2. With the aim of achieving improved treatment for colorectal cancer, we opted to combine 5-fluorouracil (5-FU), the currently used drug in the clinic, with SA. Combining SA with 5-FU, revealed a synergistic effect in which the IC50 of 5-FU decreased from 25 to 6 µM upon combination with 60 µM SA. Further, SA did not inhibit non-tumorigenic NIH-3T3 proliferation.ConclusionsWe envision that this significant decrease in the IC50 of 5-FU could translate into less side effects of 5-FU and increase the efficacy of the treatment due to the multifaceted action of SA. The data generated from the current studies on the inhibition of colorectal adenocarcinoma by SA discovered by the use of the computational program as well as synergistic action with 5-FU should open up novel therapeutic options for the management of colorectal adenocarcinomas.

Project description:This study aimed to investigate the effects of ruminal infusion of garlic oil (GO) on fermentation dynamics, fatty acid (FA) profile, and abundance of bacteria involved in biohydrogenation in the rumen. Six wethers fitted with ruminal fistula were assigned to two groups for cross-over design with a 14-d interval. Each 30-d experimental period consisted of a 27-d adaptation and a 3-d sample collection. Goats were fed a basal diet without (control) or with GO ruminal infusion (0.8 g/d). Ruminal contents collected before (0 h) and at 2, 4, 6, 8, and 10 h after morning feeding were used for fermentation analysis, and 0 h samples were further used for FA determination and DNA extraction. Garlic oil had no influence on dry matter intakes of concentrate and hay. During ruminal fermentation, GO had no effects on total VFA concentration and individual VFA molar proportions, whereas GO increased the concentrations of ammonia nitrogen and microbial crude protein (p<0.05). Compared with control, GO group took a longer time for total VFA concentration and propionate molar proportion to reach their respective maxima after morning feeding. The ratio of acetate to propionate in control reduced sharply after morning feeding, whereas it remained relatively stable in GO group. Fatty acid analysis showed that GO reduced saturated FA proportion (p<0.05), while increasing the proportions of C18, t11-18:1 (TVA), c9,t11-conjugated linoleic acid (c9,t11-CLA), t10,c12-CLA, and polyunsaturated FA (p<0.05). The values of TVA/(c9,t11-CLA+TVA) and C18:0/(TVA+ C18:0) were reduced by GO (p<0.05). Real-time PCR showed that GO tended to reduce Butyrivibrio proteoclasticus abundance (p = 0.058), whereas GO had no effect on total abundance of the Butyrivibrio group bacteria. A low correlation was found between B. proteoclasticus abundance and C18:0/(TVA+C18:0) (p = 0.910). The changes of fermentation over time suggested a role of GO in delaying the fermentation process and maintaining a relatively modest change of ruminal environment. The inhibitory effects of GO on the final step of biohydrogenation may be related to its antibacterial activity against B. proteoclasticus and other unknown bacteria involved.

Project description:BackgroundConjugated linoleic acid (cis-9, trans-11 CLA) and trans-11 vaccenic acid (VA) are found naturally in ruminant-derived foods. CLA has been shown to have numerous potential health related effects and has been extensively investigated. More recently, we have shown that VA has lipid-lowering properties associated with reduced hepatic lipidogenesis and chylomicron secretion in the JCR:LA-cp rat. The aim of this study was to evaluate potential additional hypolipidemic effects of purified forms of CLA and VA in an animal model of the metabolic syndrome (the JCR:LA-cp rat).MethodsTwenty four obese JCR:LA-cp rats were randomized and assigned to one of three nutritionally adequate iso-caloric diets containing 1% w/w cholesterol and 15% w/w fat for 16 wk: 1) control diet (CD), 2) 1.0% w/w cis-9, trans-11 CLA (CLA), 3) 1.0% w/w VA and 1% w/w cis-9, trans-11 CLA (VA+CLA). Lean rats were fed the CD to represent normolipidemic conditions.ResultsFasting plasma triglyceride (TG), total cholesterol and LDL-cholesterol concentrations were reduced in obese rats fed either the CLA diet or the VA+CLA diet as compared to the obese control group (p < 0.05, p < 0.001; p < 0.001, p < 0.01; p < 0.01, p < 0.001, respectively). The VA+CLA diet reduced plasma TG and LDL-cholesterol to the level of the normolipidemic lean rats and further decreased nonesterified fatty acids compared to the CLA diet alone. Interestingly, rats fed the VA+CLA diet had a higher food intake but lower body weight than the CLA fed group (P < 0.05). Liver weight and TG content were lower in rats fed either CLA (p < 0.05) or VA+CLA diets (p < 0.001) compared to obese control, consistent with a decreased relative protein abundance of hepatic acetyl-CoA carboxylase in both treatment groups (P < 0.01). The activity of citrate synthase was increased in liver and adipose tissue of rats fed, CLA and VA+CLA diets (p < 0.001) compared to obese control, suggesting increased mitochondrial fatty acid oxidative capacity.ConclusionWe demonstrate that the hypolipidemic effects of chronic cis-9, trans-11 CLA supplementation on circulating dyslipidemia and hepatic steatosis are enhanced by the addition of VA in the JCR:LA-cp rat.

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Ruminal microbe of biohydrogenation of trans-vaccenic acid to stearic acid in vitro.

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Ruminal microbe of biohydrogenation of trans-vaccenic acid to stearic acid in vitro.

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