Interspecies hydrogen transfer between the rumen ciliate Polyplastron multivesiculatum and Methanosarcina barkeri (original) (raw)
Related papers
Dynamics of large ciliate protozoa in the rumen of cattle fed on diets of freshly cut grass
British Journal of Nutrition, 1986
1. The dynamics of large ciliate (holotrich) protozoa (Isotricha and Dasytricha spp.) in the rumen of cattle given cut, fresh ryegrass (Lolium multiflorium Lam) were studied by means of a single intrarumen injection of 14C-labelled protozoa prepared in vitro by adding [Me 14C]choline to rurnen fluid containing protozoa and incubating at 39° for 2 h.2. An indication of the lysis rate of protozoa in the rumen was obtained from the radioactivity apparently lost through the methane pool.3. The turnover time of the holotrich protozoa indicates that these protozoa were extensively retained in the rumen and that only a small proportion of those produced in the rumen flowed out in the digesta. This was supported by the estimation of the rate of lysis which was approximately 85% of the turnover rate in the rurnen.4. The apparent production rate of the larger protozoa indicates that they contribute only about 9% of the predicted net microbial protein synthesis in the rumen.
The Role of Ciliate Protozoa in the Rumen
Frontiers in microbiology, 2015
First described in 1843, Rumen protozoa with their striking appearance were assumed to be important for the welfare of their host. However, despite contributing up to 50% of the bio-mass in the rumen, the role of protozoa in rumen microbial ecosystem remains unclear. Phylogenetic analysis of 18S rDNA libraries generated from the rumen of cattle, sheep, and goats has revealed an unexpected diversity of ciliated protozoa although variation in gene copy number between species makes it difficult to obtain absolute quantification. Despite repeated attempts it has proven impossible to maintain rumen protozoa in axenic culture. Thus it has been difficult to establish conclusively a role of ciliate protozoa in rumen fiber degradation. The development of techniques to clone and express ciliate genes in λ phage, together with bioinformatic indices to confirm the ciliate origin of the genes has allowed the isolation and characterization of fibrolytic genes from rumen protozoa. Elimination of t...
Folia Microbiologica, 2000
The methanogenic activity in the presence ofEntodinium caudatum andEpidinium ecaudatum was well preserved after long-term cultivation. Microscopic observation revealed that methane production in the presence ofE. caudatum was probably caused by their intracellular methanogenic activity, while methane production in the presence ofE. ecaudatum f.caudatum etecaudatum could be atributed to both the methanogenic bacterial fraction of their external surface and their intracellular activity. Methane production per protozoan cell ofE. caudatum andE. ecaudatum was 2.1 nmol per cell per d and 6.0 nmol. per cell per d, respectively.E. caudatum was responsible for almost the entire methane production in the culture. The activity of free methanogens constituted approximately 50% of the total methane production in thee. ecaudatum culture. Decrease of digestibility of substrates and differences in the fermentation end products accompanied the inhibition of methanogenesis in both cultures by penicillin G. streptomycin, chloramphenicol, 2-bromoethanesulfonate, and pyromellitic diimideE. caudatum appeared to be more sensitive thanE. ecaudatum to the compounds tested. Hydrogen recoveries based on both volatile fatty acids and methane production suggested that the methanogenic population appeared not to be fully able to consume hydrogen produced in the protozoan cultures. The culture conditions tested were found to be suitable for experiments on the relationship between rumen ciliate and rumen bacteria.
Postprandial variations in endogenous metabolic activities of ovine rumen ciliate protozoa
Animal Feed Science and Technology, 1995
The effects of diet and of time after feeding on the endogenous metabolism of four different subfractions of rumen ciliate protozoa (mixed population, large entodiniomorphid, Isotricha and Dasytricha spp.) were examined, with respect to the production of gas, acetate, butyrate and L-lactate and rates of uptake of glucose. The type of feed, and time after feeding, had a marked effect on the composition of the sampled rumen protozoa1 population, with respect to metabolic activity of the component groups. The heterogeneity of these subpopulations, with respect to their relative metabolic activities at different times, are clearly demonstrated. The data are in general accord with related findings; e.g. protozoa from-sugar-beet-fed animals were more active than those from hay-fed animals, and previous measurements of rumen dissolved gases agreed with the present measurements of activity within protozoa.
Kinetics of large ciliate protozoa in the rumen of cattle given sugar cane diets
British Journal of Nutrition, 1981
1. Experiments were undertaken to examine the kinetics of large ciliate protozoa in the rumen of cattle on sugar-cane diets.2. Three Zebu bulls were fed once daily on a diet of sugar cane and wheat bran. The diurnal patterns of volatile fatty acids and ammonia concentrations, and the numbers of protozoa in rumen fluid were determined. The numbers of protozoa reached values of 5 × 104/ml for holotrichs (large ciliates) mainly Isoiricha and Dasytricha spp and 4 × 105 for smaller protozoa, mainiy Entodinia (small ciliates)3. A method was developed which allowed large ciliate protozoa in rumen fluid to be separated from plant material and bacteria and concentrated in a relatively uncontaminated form. Analysis of these protozoa indicated that 1.8 × 105 large ciliates contained 1 mg nitrogen and approximately 32 mg dry matter4. A labelled preparation consisting mainly of large ciliates (principally Isotricha spp.) was obtained by incubating isolated protozoa in rumen fluid (free of plant ...
Archives of Animal Nutrition, 2012
The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hayconcentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 6 2 6 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM þ EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52-and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH 4 -to-CO 2 ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.
Some rumen ciliates have endosymbiotic methanogens
FEMS Microbiology …, 1994
Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F420 autofluorescence and they were detected with a rhodamine-labelled Archaea-specific oligonucleotide probe. The measured volume percent of autofluorescing bacteria (1%) was close to the total volume of intracellular bacteria estimated from TEM stereology. Thus it is likely that all of the bacteria living in the cytoplasm of these ciliates were endosymbiotic methanogens, using H 2 evolved by the host ciliate to form methane. Intracellular methanogens appear to be much more numerous than those attached to the external cell surface of ciliates.