Microbes involved in dissimilatory nitrate reduction in the human large intestine

Parham, Nick J.; Gibson, Glenn R.

doi:10.1111/j.1574-6941.2000.tb00667.x

Cited by 20 publications

(19 citation statements)

References 43 publications

(46 reference statements)

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“…27 Despite its natural abundance in food, nitrate has been considered to have negative health effects, due to the fact that it can be transformed into nitrite (which has an MCL of only 1 mg L −1 ) by bacterial nitrate reductases (NR) in the oral cavity 28–30 and gastrointestinal tract. 31–33 …”

Section: Nitrate Reductionmentioning

confidence: 99%

Nitrate and periplasmic nitrate reductases

2014

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The nitrate anion is a simple, abundant and relatively stable species, yet plays a significant role in global cycling of nitrogen, global climate change, and human health. Although it has been known for quite some time that nitrate is an important species environmentally, recent studies have identified potential medical applications. In this respect the nitrate anion remains an enigmatic species that promises to offer exciting science in years to come. Many bacteria readily reduce nitrate to nitrite via nitrate reductases. Classified into three distinct types – periplasmic nitrate reductase (Nap), respiratory nitrate reductase (Nar) and assimilatory nitrate reductase (Nas), they are defined by their cellular location, operon organization and active site structure. Of these, Nap proteins are the focus of this review. Despite similarities in the catalytic and spectroscopic properties Nap from different Proteobacteria are phylogenetically distinct. This review has two major sections: in the first section, nitrate in the nitrogen cycle and human health, taxonomy of nitrate reductases, assimilatory and dissimilatory nitrate reduction, cellular locations of nitrate reductases, structural and redox chemistry are discussed. The second section focuses on the features of periplasmic nitrate reductase where the catalytic subunit of the Nap and its kinetic properties, auxiliary Nap proteins, operon structure and phylogenetic relationships are discussed.

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Section: Nitrate Reductionmentioning

confidence: 99%

Nitrate and periplasmic nitrate reductases

2014

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“…Allison and Macfarlane [26] reported that DNRA is the major pathway for nitrate reduction by the fecal microbiota. Identification based on phenotype and genotype showed that Clostridium ramosum , Bacteroides vulgates, and the enterobacteriaceae were mainly capable of DNRA [27]. These species are representative for the dominant groups of the fecal microbiota [31, 32].…”

Section: Discussionmentioning

confidence: 99%

“…Three possible pathways were considered (i) L-arginine as substrate for NO synthase, (ii) denitrification to nitrogen gas and (iii) dissimilatory nitrate reduction to ammonium (DNRA). The latter was considered as fermentative nitrate reduction is expected under gastrointestinal conditions however no relation with NO production has been considered [26, 27]. …”

Section: Introductionmentioning

confidence: 99%

Nitric Oxide Production by the Human Intestinal Microbiota by Dissimilatory Nitrate Reduction to Ammonium

Vermeiren

Wiele

Verstraete

et al. 2009

BioMed Research International

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The free radical nitric oxide (NO) is an important signaling molecule in the gastrointestinal tract. Besides eukaryotic cells, gut microorganisms are also capable of producing NO. However, the exact mechanism of NO production by the gut microorganisms is unknown. Microbial NO production was examined under in vitro conditions simulating the gastrointestinal ecosystem using L-arginine or nitrate as substrates. L-arginine did not influence the microbial NO production. However, NO concentrations in the order of 90 ng NO-N per L feed medium were produced by the fecal microbiota from nitrate. 15N tracer experiments showed that nitrate was mainly reduced to ammonium by the dissimilatory nitrate reduction to ammonium (DNRA) pathway. To our knowledge, this is the first study showing that gastrointestinal microbiota can generate substantial amounts of NO by DNRA and not by the generally accepted denitrification or L-arginine pathway. Further work is needed to elucidate the exact role between NO produced by the gastrointestinal microbiota and host cells.

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“…In vivo conditions may have affected bacterial NO production by propionibacteria as compared with in vitro ones, and have stimulated NO production from TL15. Alternatively, considering that the commensal intestinal bacteria intensively reduce nitrate to ammonia [33], the in vivo conditions may also have inhibited NO production by TL223 due to competition for nitrate.…”

Section: Discussionmentioning

confidence: 99%

“…Production of bacterial NO has been extensively described in established environmental denitrifiers such as Pseudomonas and Paracoccus [49] but it is very unusual for bacteria which are encountered in the intestine. Indeed, the commensal intestinal flora can efficiently reduce nitrate and nitrite but this phenomenon occurs mainly via a dissimilatory reaction where ammoniac is the final product of nitrite reduction [33]. One exception is some enteric bacteria, which can produce small amounts of NO from nitrite reduction [13].…”

Section: Discussionmentioning

confidence: 99%

Colonic infusion with Propionibacterium acidipropionici reduces severity of chemically-induced colitis in rats

Michel

Roland

Lecannu

et al. 2005

Lait

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-Propionibacteria are cheese starters, also studied for their probiotic potential. An interesting feature is the ability of some strains to synthesize nitric oxide (NO) from nitrate reduction. NO production is hypothesized to be the mechanism by which some probiotics improve the mucosal barrier in rats. We therefore investigated the ability of two Propionibacterium acidipropionici strains (TL15 & TL223), which differ in their in vitro production of NO, to improve colitis in rats. Three groups of rats in which colitis was induced by trinitrobenzene sulfonic acid (TNBS), received intracolonic infusions of 9 g·L -1 NaCl (n = 6), or 0.9 × 10 10 CFU·d -1 of TL15 (n = 7), or 1.4 × 10 10 CFU·d -1 of TL223 (n = 7), for 7 days. Following treatment, animal weight, food consumption, inflammatory score and myeloperoxydase (MPO) activity, together with changes in intestinal bacteria and SCFA concentrations, were investigated. As expected, both TL223 and TL15 supplements induced detectable counts of P. acidipropionici in colonic contents of rats (7.67 ± 0.67 and 7.43 ± 0.50 log eq. CFU·g -1 , respectively, as determined by real-time PCR). Food consumption and body weight of rats receiving propionibacteria were overall higher than those of rats with NaCl (P = 0.007 and P = 0.004). Moreover, both propionibacteria infusions similarly and dramatically reduced the gross score for inflammation (P = 0.004) as compared with NaCl (0.6 ± 0.3 and 0.7 ± 0.5 vs. 4.8 ± 1.5). A similar effect was observed for MPO activity (P = 0.056), which reached 2.50 ± 1.37 U·g -1 of mucosal tissue for NaCl vs. 0.05 ± 0.02 and 0.26 ± 0.18 U·g -1 for TL223 and TL15, respectively. This study shows for the first time the potential benefit of propionibacteria in colonic mucosa healing, but the mechanism involved needs to be elucidated.Propionibacterium / probiotic / colonic ulceration / nitric oxide / real-time PCR Résumé -L'administration colique de Propionibacterium acidopropionici atténue la sévérité de la colite induite chez le rat. Les bactéries propioniques, utilisées comme levains fromagers, sont également étudiées pour leurs propriétés probiotiques. Une caractéristique intéressante concerne la capacité de certaines souches à synthétiser du monoxyde d'azote (NO) lors de la réduction des nitrates. La production de NO est évoquée comme mécanisme d'action de certains probiotiques capables de restaurer la muqueuse intestinale chez des rats. Nous avons donc déterminé l'impact de deux souches de Propionibacterium acidipropionici (TL15 & TL223) présentant des capacités de synthèse de NO différentes in vitro, sur des colites induites chez le rat. Trois groupes de rats à colite induite par le trinitrobenzene sulfonic acid (TNBS) ont reçu pendant 7 j des infusions intracoliques de solution * Corresponding author: michel@nantes.inra.fr 100 C. Michel et al.saline (9 g·L -1 NaCl), ou de suspensions de TL15 (0,9 × 10 10 UFC·j -1 ) ou de TL223 (1,4 × 10 10 UFC·j -1 ). Les effets des traitements sur le poids des animaux, leur consommation alimentaire, le sco...

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Microbes involved in dissimilatory nitrate reduction in the human large intestine

Cited by 20 publications

References 43 publications

Nitrate and periplasmic nitrate reductases

Nitrate and periplasmic nitrate reductases

Nitric Oxide Production by the Human Intestinal Microbiota by Dissimilatory Nitrate Reduction to Ammonium

Colonic infusion with Propionibacterium acidipropionici reduces severity of chemically-induced colitis in rats

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