Dissimilatory Amino Acid Metabolism in Human Colonic Bacteria

Smith, E. A.; Macfarlane, G.T.

doi:10.1006/anae.1997.0121

Cited by 301 publications

(249 citation statements)

References 45 publications

Supporting

Mentioning

234

Contrasting

Unclassified

Order By: Relevance

“…Although SCFA are mainly derived from saccharolytic fermentation, they can also be derived from amino acids, such as lysine or histidine, through reductive deamination (32) . However, apart from butyrate, our diets high in CP also increased the luminal concentrations of NH 3 and biogenic amines.…”

Section: Discussionmentioning

confidence: 99%

Down-regulation of monocarboxylate transporter 1 (MCT1) gene expression in the colon of piglets is linked to bacterial protein fermentation and pro-inflammatory cytokine-mediated signalling

et al. 2015

View full text Add to dashboard Cite

The present study investigated the influence of bacterial metabolites on monocarboxylate transporter 1 (MCT1) expression in pigs using in vivo, ex vivo and in vitro approaches. Piglets (n 24) were fed high-protein (26 %) or low-protein (18 %) diets with or without fermentable carbohydrates. Colonic digesta samples were analysed for a broad range of bacterial metabolites. The expression of MCT1, TNF-a, interferon g (IFN-g) and IL-8 was determined in colonic tissue. The expression of MCT1 was lower and of TNF-a and IL-8 was higher with high-protein diets (P, 0·05). MCT1 expression was positively correlated with L-lactate, whereas negatively correlated with NH 3 and putrescine (P,0·05). The expression of IL-8 and TNF-a was negatively correlated with L-lactate and positively correlated with NH 3 and putrescine, whereas the expression of IFN-g was positively correlated with histamine and 4-ethylphenol (P,0·05). Subsequently, porcine colonic tissue and Caco-2 cells were incubated with Na-butyrate, NH 4 Cl or TNF-a as selected bacterial metabolites or mediators of inflammation. Colonic MCT1 expression was higher after incubation with Na-butyrate (P,0·05) and lower after incubation with NH 4 Cl or TNF-a (P,0·05). Incubation of Caco-2 cells with increasing concentrations of these metabolites confirmed the up-regulation of MCT1 expression by Na-butyrate (linear, P, 0·05) and down-regulation by TNF-a and NH 4 Cl (linear, P,0·05). The high-protein diet decreased the expression of MCT1 in the colon of pigs, which appears to be linked to NH 3 -and TNF-a-mediated signalling.

show abstract

Section: Discussionmentioning

confidence: 99%

Down-regulation of monocarboxylate transporter 1 (MCT1) gene expression in the colon of piglets is linked to bacterial protein fermentation and pro-inflammatory cytokine-mediated signalling

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Secondly, the products of carbohydrate fermentation, such as lactic acid and VFAs would also reduce the digesta pH, creating conditions unfavourable for the growth of protein fermenting bacteria (Smith and MacFarlane, 1997). At lower pH values, carbohydrate-fermenting bacteria incorporate more free amino acids into microbial protein, thus further limiting the potential for ammonia volatilisation.…”

Section: Wheatmentioning

confidence: 99%

“…At lower pH values, carbohydrate-fermenting bacteria incorporate more free amino acids into microbial protein, thus further limiting the potential for ammonia volatilisation. An additional effect of this is that it reduces the availability of substrate for protein fermenting bacteria (Smith and MacFarlane, 1997), with consequential beneficial effects on odour release. Because the products of fermentation are influenced by the population of bacteria within the gut, it is imputed that the addition of an enzyme will also affect the production of these products.…”

Section: Wheatmentioning

confidence: 99%

The effect of cereal type and enzyme addition on pig performance, intestinal microflora, and ammonia and odour emissions

Garry

Fogarty

Curran

et al. 2007

Animal

View full text Add to dashboard Cite

Two 2 £ 2 factorial experiments were conducted to investigate the interaction between cereal type (wheat v. barley) and exogenous enzyme supplementation (with or without) on odour and ammonia emissions (experiment 1) and growth performance (experiment 2) in grower-finisher pigs. The enzyme supplement used contained endo-1, 3 (4) -b-glucanase (EC 3.2.1.6) and endo-1, 4 -b-xylanase (E.C 3.2.1.8). The diets were formulated to contain similar levels of net energy (9.8 MJ/kg) and lysine (10.0 g/kg). The experimental treatments were as follows: (1) wheat-based diet, (2) wheat-based diet containing a b-glucanase and b-xylanase mixed enzyme supplement, (3) barley-based diet and (4) barley-based diet containing a b-glucanase and bxylanase mixed enzyme supplement. In experiment 1, the diets were offered to the pigs for 23 days in sealed pens (eight pigs per pen) and this was repeated four times (n ¼ 4). Odour and ammonia emissions were measured on days 9, 11, 14, 16, 21 and 23 of each replicate period. Odour samples were collected in 20-l Nalophan bags and analysed for odour concentration using an ECOMA Yes/No Olfactometer. Ammonia concentrations in the ventilation air were measured using Drä ger tubes. In experiment 2, 220 pigs were group fed in mixed sex pens using single-space feeders (11 pigs per feeder, six boars and five gilts) (n ¼ 5). There was a cereal £ enzyme interaction in odour emission rates, ammonia emissions and selected microbial populations in the caecum and colon (P , 0.05). The addition of an enzyme supplement to the barley-based diet increased both odour and ammonia emission, however the addition of an enzyme to the wheat-based diet decreased ammonia emission rates and had no effect on odour emission. Pigs offered the unsupplemented barley-based diet had a significantly (P , 0.05) lower population of Enterobacteriaceae spp. and a higher population of Bifidobacteria spp. compared with enzyme-supplemented barley diets. However, there was no effect of enzyme supplementation in wheat-based diets. In the performance experiment, neither cereal type nor enzyme inclusion had an effect on pig performance or carcass characteristics. In conclusion, the inclusion of an enzyme mix to barley-based diets increased odour and ammonia emissions, while the addition of an enzyme mix to wheat-based diets decreased ammonia emissions.

show abstract

“…5), leading us to propose that HypD is likely responsible for the anaerobic Hyp degradation previously observed in human fecal and gingival samples. 28 , 29 In addition to human commensals, HypD is also encoded in several notable human pathogens including C. difficile and Clostridium botulinum (Fig. 5).…”

Section: Introductionmentioning

confidence: 99%

Anaerobic 4-hydroxyproline utilization: Discovery of a new glycyl radical enzyme in the human gut microbiome uncovers a widespread microbial metabolic activity

2018

View full text Add to dashboard Cite

The discovery of enzymes responsible for previously unappreciated microbial metabolic pathways furthers our understanding of host-microbe and microbe-microbe interactions. We recently identified and characterized a new gut microbial glycyl radical enzyme (GRE) responsible for anaerobic metabolism of trans-4-hydroxy-l-proline (Hyp). Hyp dehydratase (HypD) catalyzes the removal of water from Hyp to generate Δ1-pyrroline-5-carboxylate (P5C). This enzyme is encoded in the genomes of a diverse set of gut anaerobes and is prevalent and abundant in healthy human stool metagenomes. Here, we discuss the roles HypD may play in different microbial metabolic pathways as well as the potential implications of this activity for colonization resistance and pathogenesis within the human gut. Finally, we present evidence of anaerobic Hyp metabolism in sediments through enrichment culturing of Hyp-degrading bacteria, highlighting the wide distribution of this pathway in anoxic environments beyond the human gut.

show abstract

Dissimilatory Amino Acid Metabolism in Human Colonic Bacteria

Cited by 301 publications

References 45 publications

Down-regulation of monocarboxylate transporter 1 (MCT1) gene expression in the colon of piglets is linked to bacterial protein fermentation and pro-inflammatory cytokine-mediated signalling

Down-regulation of monocarboxylate transporter 1 (MCT1) gene expression in the colon of piglets is linked to bacterial protein fermentation and pro-inflammatory cytokine-mediated signalling

The effect of cereal type and enzyme addition on pig performance, intestinal microflora, and ammonia and odour emissions

Anaerobic 4-hydroxyproline utilization: Discovery of a new glycyl radical enzyme in the human gut microbiome uncovers a widespread microbial metabolic activity

Contact Info

Product

Resources

About