The rumen as a model of the microbiology of fibre digestion in the human intestine

Henderson, C. A.; Demeyer, Daniël

doi:10.1016/0377-8401(89)90099-0

Cited by 15 publications

(10 citation statements)

References 56 publications

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“…Bacteroides sp. and Runaiiaococcus albus, pH, gasphase and retention time, clear differences occcur as well, considering the nature of substrate, the presence of endogenous compounds, the presence of d a t e protozoa (mostly absent in the hindgut, except for horses and sometimes rabbits) and fungi (absent, except for the hindgut of some large ruminants) (Orpin, 1981;Henderson and Demeyer, 1989;Vervaeke et al, 1989;Cummings and Macfarlane, 1991). Based on the differences listed, research was developed in our lab in order to understand better factors determining competition between M and RA (see below).…”

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confidence: 99%

Reductive Acetogenesis in the Hindgut and Attempts to its Induction in the Rumen—A Review

Fievez

Piattoni

Mbanzamihigo

et al. 1999

Journal of Applied Animal Research

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Fievez, V., Piattoni, F., Mbanzamihigo, L. and Demeyer, D. 1999. Reductive acetogenesis in the hindgut and attempts to its induction in the rumen-A review. J. Appl. Anim. Res., 16: 1-22. Hiridgut ferrneiitatiori differs froin ruinen fermentation b. y a. lower methane production and the presence of reductive acetogenesis (RA).Moreover, it has been showii tha.t with ageing RA is rephced coinpletely (ruinen) or partially (hindgut) A. IntroductionBesides methanogenesis (M), non assimilatory sulphate reduction and/ or reductive acetogenesis (RA) have been identified as major pathways of microbial competition for metabolic hydrogen, formed during bacterial fermentation in anaerobic microbial ecosystems. However, these alternative hydrogen sinks to M do not function in the rumen, although bacteria able to use them have been isolated . After a short introduction to the characteristics of RA, this paper intends to give a global review of the research carried out in our laboratory over the past five years, related both to the relative importance of RA and M and to the possibilities for induction of RA in the rumen. A.1. RA in the gastro-intestinal tractBacteria are defined as reductive acetogens when they are able to reduce 2 moles of CO, to 1 mole of acetate, either autotrophically or heterotrophically, e.g. homoacetogenesis (Fisher et al., 1932; Wieringa, 1936, Prins andLankhorst, 1977).The heterotrophic growth of hom,oacetogens is characterised by the (almost) complete conversion of monosaccharides to acetate (Ljungdahl, 1986 Moreover, most of the hoinoacetogens are able to reduce exogenous CO,> autotrophically with molecular H,: 2 CO, + 4H, 3 CH,COOH + 2HiO ( 3 ) . This ability of mixothrophic growth (i.e. autotrophically on CO,-H, --a n d heterotrophically on monosaccharides) enables these acetogens to survive in almost every anaerobic environment and could explain their rather high growth yields (Ljungdahl, 1986). A.2. Detection of the occurrence of RAThe amounts of end products formed in ruinen fermentation are related through the stoichiometery of the overall reaction concerned (Wolin, 1960). This allows calculation of the net amounts of "metabolic hydrogen" produced and recovered in reduced end products. The agreement of the amounts of end products formed within a fermentation, with the overall reactions proposed, can then be evaluated by calculation of a "hydrogen recovery (2Hr)" (Marty and Demeyer, 1973): 100 * (2P + 2B + 4CHJ / (2A + P + 4B), with A, P, B and CH, equal to the molar amounts of acetate, propionate, butyrate and methane, respectively.With rumen contents such recoveries range between 80 and 90% (Demeyer, 1991), whereas with hindgut contents from different species, values were much lower, suggesting the presence of other hydrogen consuming reactions, mainly RA (Henderson a n d Deineyer and De Graeve, 1991). However, this calculation does not allow to differentiate reaction (2) from (3) and, therefore, in this paper RA is used for both reactions. A.3. Competition and similarity betwee...

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confidence: 99%

Reductive Acetogenesis in the Hindgut and Attempts to its Induction in the Rumen—A Review

Fievez

Piattoni

Mbanzamihigo

et al. 1999

Journal of Applied Animal Research

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“…Moreover, it is clear that the substitution of acetogenesis for methanogenesis in the rumen would result in considerable improvement of feed energy utilisation in ruminants, as well as in the reduction of overall methane emission in the environment (see eg, Van Nevel and Demeyer, 1995 al, 1994) and in the human faecal flora . In the rumen, however, methane inhibition by BES increases propionate proportion (De Graeve et al, 1994 and of free amino acids (Van Nevel and Demeyer, 1990) (Henderson and Demeyer, 1989;Demeyer, 1991) and/or the response of the fermentation pattern to increased head space H 2 (Demeyer and De Graeve, 1991 ). Incubations were stopped by injecting 1 ml of 10 N H 2 SO 4 and the volatile fatty acids, methane, H 2 and ammonia concentrations were determined before and after incubations as described previously (Van Nevel and …”

Section: Introductionmentioning

confidence: 99%

Attempted induction of reductive acetogenesis into the rumen fermentation in vitro

Demeyer¹,

Fiedler²,

Graeve³

1996

Reprod. Nutr. Dev.

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Summary ― Rumen and caecal contents, obtained from slaughterhouse cattle and rumen contents obtained from a fistulated wether were incubated in vitro with ground hay in the presence and absence of, respectively, casein hydrolysate and mucin. Differences in stoichiometry of rumen and caecal fermentations, indicative of reductive acetogenesis in the caecum, were confirmed, except for incubations with free amino acids. Net fermentation end product production was determined after correction for amounts formed in incubations without the substrate. These determined amounts of hay fermentation end products were compared with the amounts calculated from incubations of hay with added casein hydrolysate or mucin, corrected for amounts formed from the latter added substrates incubated alone. With casein hydrolysate, no differences between the determined and calculated amounts were observed, excluding the occurrence of reductive acetogenesis from hay in the presence of free amino acids. With mucin, the calculated amounts indicated an inhibition of methanogenesis, accompanied by increased amounts of proprionate, butyrate and valerate production. This finding was probably related to the greater availability of easily fermented carbohydrates in the presence of mucins. The absence of an increased acetate production in the incubations with added head space hydrogen gas, also indicate the absence of reductive acetogenesis from hay in the presence of mucin.

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“…Nearly all SA are readily fermented by microbes in the lower gut. Only traces are found in the faeces which, however, contain small amounts of their degradation products, mainly VFA (Nutrition Council, 1987;Ziesenitz & Siebert, 1987;Henderson & Demeyer, 1988;Grimble, 1989;Bergman, 1990;Giesecke, 1990). Faecal energy loss is somewhat higher after SA intake.…”

Section: O D I F Y I N G T H E E N E R G Y D E N S I T Y O F H U M mentioning

confidence: 99%

“…Unfortunately most animal species suited for such work have a digestive tract that differs from that of man, especially with regard to the location and extent of microbial fermentation (Ratcliffe, 1985;Henderson & Demeyer, 1988;Giesecke, 1990). Moreover, pigs, rodents and poultry are not often fed on Western-type human diets which have a high fat content and digestibility.…”

Section: The Net Energy ( N E ; Atp) Potential O F S Amentioning

confidence: 99%

“…Another possibly advantageous effect for those SA that reach the large intestine is the stimulation of microbial fermentation in that part of the gut. This may lead to shorter transit times for digesta due to the osmotic properties of the SA and of their degradation products, the volatile fatty acids (VFA), and lead to a greater supply of butyric acid, to a lower pH and possibly to some neutralization of free radicals (Gibson et al 1988;Henderson & Demeyer, 1988;Bergman, 1990). However, too much fermentation might give excessive gas formation, diarrhoea and, possibly, undesirable nitrate and sulphate reduction (Grimble, 1989).…”

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Dietary energy density on using sugar alcohols as replacements for sugars

1991

proc nutr soc

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The rumen as a model of the microbiology of fibre digestion in the human intestine

Cited by 15 publications

References 56 publications

Reductive Acetogenesis in the Hindgut and Attempts to its Induction in the Rumen—A Review

Reductive Acetogenesis in the Hindgut and Attempts to its Induction in the Rumen—A Review

Attempted induction of reductive acetogenesis into the rumen fermentation in vitro

Dietary energy density on using sugar alcohols as replacements for sugars

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