Association of methanogenic bacteria with ovine rumen ciliates

Abstract

1. The frequency of association between methanogenic bacteria and ovine rumen ciliates was studied in the rumen fluid of a fistulated sheep. 2.A period of fasting and flushing of the rumen content with nitrogen resulted in a relatively high association, whereas the intake of food and flushing with hydrogen caused a detachment of the methanogenic bacteria from the ciliates.3. The changes in the frequency of association can be correlated with the relative attribution to the H, production by hydrogenogenic bacteria and rumen ciliates.In the anaerobic environment of the rumen various nutritional interrelationships exist between bacteria and ciliates (Wolin, 1979;Prins & Clarke, 1980). One of these interactions consists of the production of hydrogen by bacteria (Joyner et al. 1977) and ciliates (Abou Akkada & Howard, 1960;Hungate, 1966; Prins & Prast, 1973;Williams & Harfoot, 1976) and the utilization of H, as substrates for the production of methane by methanogenic bacteria (Hungate, 1967;Hungate et al. 1970). Recently Vogels et al. (1980) described a somatic association between methanogenic bacteria and several species of entodiniomorph ciliates from rumens of slaughtered cows. We now report the results of a study concerning methanogen-ciliate association in the rumen of a fistulated sheep under various circumstances of fasting and feeding. MATERIALS A N D METHODSA Texel ram (body-weight 98 kg) was provided with a rumen fistula. Rumen fluid was taken anaerobically by means of a water suction pump. The experiments were performed during the summer season and the sheep was kept on a pasture. Part of the samples were taken after the animal had been fasted for 14 h (during the night). Measurement of methane productionAmounts of 3 ml rumen fluid were injected anaerobically into 50 ml bottles with 30 ml liquid medium according to Clarke (1963) and a gas phase of nitrogen-carbon dioxide (80 : 20, v/v) containing a small amount of ethane as the reference gas. The bottles were incubated in a New Brunswick G24 shaker at 190 rev./min and 39". Every hour during a period of 4 h a gas sample was taken and the methane content was measured in a Pye Unicam GCV gas-liquid chromatograph. The methane production was calculated by the zero-time rate method (Hungate, 1966). The results were expressed as 1 CH, produced/ 1 rumen fluid per 24 h. Interaction of methanogenic bacteria with ciliatesThe methanogen-ciliate association was checked by means of Leitz epifluorescence microscopy as described earlier (Vogels et al. 1980) and is defined positive if at least twenty bacteria were attached to a ciliate cell. At least 100 ciliates were randomly checked in each rumen sample immediately after collection. Because Eudiplodinium maggii and Diplodinium dentatum were most numerous among the entodiniomorphs the values reported refer only to these two species. 4-2at https://www.cambridge.org/core/terms. https://doi

Microbial ecosystem and methanogenesis in ruminants

“…H 2 is a fermentation by-product that is produced in large quantities by the protozoa in a specialised organelle equivalent to the mitochondria of aerobic eukaryotes: the hydrogenosome. This H 2 is utilised by methanogens that are found inside (Finlay et al, 1994) or in close association with protozoal cells (Stumm et al, 1982). This interaction is a typical example of interspecies H 2 transfer that favours both the methanogens and the protozoa (Hillman et al, 1988;Ushida et al, 1997).…”

“…The extent of the association is influenced by diet and time of feeding (Stumm et al, 1982;Tokura et al, 1997). Adherence of methanogens to protozoa is low after feeding and appears to be related to the relative abundance of H 2 in the medium (Stumm et al, 1982). Most Entodiniomorphs seem able to carry methanogens on their surface, but no episymbiotic methanogens were observed associated with Holotrichs protozoa (Vogels et al, 1980).…”

Effects of disodium fumarate on ruminal fermentation and microbial communities in sheep fed on high-forage diets

“…Protozoa serve not only as host for methanogens, but also produce hydrogen in large quantities in a specialized organelle (hydrogenosome; Morgavi et al, 2010). This hydrogen is metabolized by methanogens that are found inside (Finlay et al, 1994) or in close association with protozoal cells (Stumm et al, 1982). The interaction between methanogens and protozoa is a typical example of interspecies hydrogen transfer, which favors both of them (Hillman et al, 1988;Ushida and Jouany, 1996).…”

Mitigation strategies to reduce enteric methane emissions from dairy cows: Update review

“…Whitelaw et al (1984) observed that faunated cattle fed barley diets at restricted levels lost about 12% of GEI as CH 4 compared to 6-8% of GEI in ciliate-free animals. Protozoa in the rumen are associated with a high proportion of H 2 production, and are closely associated with methanogens by providing a habitat for up to 20% of rumen methanogens (Stumm et al 1982;Newbold et al 1995a). Finlay et al (1994) reported that protozoa could account for 37% of the total CH 4 production.…”