The rumen protozoa

Williams, Alan G.; Coleman, G.

doi:10.1007/978-94-009-1453-7_3

Cited by 199 publications

(268 citation statements)

References 286 publications

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“…Some methanogens are associated with the external surface of protozoa, and/or are endosymbionts, living free within the protozoal cytoplasm (Williams and Coleman, 1997). In this study, the abundance of the protozoa population within the fluid samples was decreased compared with control in Trial 1 (Table 3), whereas in Trial 2 the extended feeding of DF caused their abundance in both solid and fluid samples to recover to 0 w levels (Table 5).…”

Section: Discussionmentioning

confidence: 52%

“…Nevertheless, in Trial 1, solid-associated B. fibrisolvens is inversely related with ammonia N, whereas fluid-associated bacteria are positively correlated with ammonia N concentration. B. fibrisolvens require ammonia N for optimal growth when feeding fibrous basal diets (Williams and Coleman, 1997). The effects of DF addition on protein degradation need further studies.…”

Section: Discussionmentioning

confidence: 99%

“…Hydrogen metabolism plays a central role in regulating rumen fermentation (Hungate, 1967;Williams and Coleman, 1997). Efficient removal of hydrogen from the rumen is beneficial to increase the rate of fermentation by eliminating its inhibitory effect on the microbial degradation of plant material (Wolin, 1979;McAllister and Newbold, 2008).…”

Section: Introductionmentioning

confidence: 99%

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

Zhou

McSweeney

Wang

et al. 2012

Animal

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This study was conducted to investigate effects of disodium fumarate (DF) on fermentation characteristics and microbial populations in the rumen of Hu sheep fed on high-forage diets. Two complementary feeding trials were conducted. In Trial 1, six Hu sheep fitted with ruminal cannulae were randomly allocated to a 2 3 2 cross-over design involving dietary treatments of either 0 or 20 g DF daily. Total DNA was extracted from the fluid-and solid-associated rumen microbes, respectively. Numbers of 16S rDNA gene copies associated with rumen methanogens and bacteria, and 18S rDNA gene copies associated with rumen protozoa and fungi were measured using real-time PCR, and expressed as proportion of total rumen bacteria 16S rDNA. Ruminal pH decreased in the DF group compared with the control (P , 0.05). Total volatile fatty acids increased (P , 0.001), but butyrate decreased (P , 0.01). Addition of DF inhibited the growth of methanogens, protozoa, fungi and Ruminococcus flavefaciens in fluid samples. Both Ruminococcus albus and Butyrivibrio fibrisolvens populations increased (P , 0.001) in particle-associated samples. Trial 2 was conducted to investigate the adaptive response of rumen microbes to DF. Three cannulated sheep were fed on basal diet for 2 weeks and continuously for 4 weeks with supplementation of DF at a level of 20 g/day. Ruminal samples were collected every week to analyze fermentation parameters and microbial populations. No effects of DF were observed on pH, acetate and butyrate (P . 0.05). Populations of methanogens and R. flavefaciens decreased in the fluid samples (P , 0.001), whereas addition of DF stimulated the population of solid-associated Fibrobacter succinogenes. Population of R. albus increased in the 2nd to 4th week in fluid-associated samples and was threefold higher in the 4th week than control week in solid samples. Analysis of denaturing gradient gel electrophoresis fingerprints revealed that there were significant changes in rumen microbiota after adding DF. Ten of 15 clone sequences from cut-out bands appearing in both the 2nd and the 4th week were 94% to 100% similar to Prevotella-like bacteria, and four sequences showed 95% to 98% similarity to Selenomonas dianae. Another 15 sequences were obtained from bands, which appeared in the 4th week only. Thirteen of these 15 sequences showed 95% to 99% similarity to Clostridium sp., and the other two showed 95% and 100% similarity to Ruminococcus sp. In summary, the microorganisms positively responding to DF addition were the cellulolytic bacteria, R. albus, F. succinogenes and B. fibrisolvens as well as proteolytic bacteria, B. fibrisolvens, P. ruminicola and Clostridium sp.

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Section: Discussionmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 99%

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

Zhou

McSweeney

Wang

et al. 2012

Animal

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“…Experiment 1: Role of I. prostoma and its associated bacteria in rumen biohydrogenation Protozoa were obtained using a sedimentation procedure as described by Williams and Coleman (1992) with some modifications. Briefly, 200 ml of I. prostoma monofaunated rumen fluid was mixed with 400 ml of Simplex type Coleman buffer (Coleman, 1978), prepared as recommended by Broudiscou and Lassalas (2000), and 0.6 g of glucose.…”

Section: In Vitro Incubationsmentioning

confidence: 99%

“…However, the unequivocal role of protozoa in the hydrogenation of unsaturated fatty acids cannot be assessed from these in vitro studies since bacterial contamination cannot be excluded from protozoal fractions (Dawson and Kemp, 1969). It is well known that protozoa contain bacteria in vesicles in their endoplasm (endosymbionts) and/or have bacteria attached to the outside of the pellicle (ectosymbionts) (Williams and Coleman, 1992). The above-mentioned results are therefore inconclusive.…”

Section: Introductionmentioning

confidence: 99%

Role of the protozoan Isotricha prostoma, liquid-, and solid-associated bacteria in rumen biohydrogenation of linoleic acid

Boeckaert

Morgavi

Jouany

et al. 2009

Animal

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From the simultaneous accumulation of hydrogenation intermediates and the disappearance of Isotricha prostoma after algae supplementation, we suggested a role of this ciliate and/or its associated bacteria in rumen biohydrogenation of unsaturated fatty acids. The experiments described here evaluated the role of I. prostoma and/or its associated endogenous and exogenous bacteria in rumen biohydrogenation of C18:2n-6 and its main intermediates CLA c9t11 and C18:1t11. Fractions of I. prostoma and associated bacteria, obtained by sedimentation of rumen fluid sampled from a monofaunated sheep, were used untreated, treated with antibiotics or sonicated to discriminate between the activity of I. prostoma and its associated bacteria, the protozoan or the bacteria, respectively. Incubations were performed in triplicate during 6 h with unesterified C18:2n-6, CLA c9t11 or C18:1t11 (400 mg/ml) and 0.1 g glucose/cellobiose (1/1, w/w). I. prostoma did not hydrogenate C18:2n-6 or its intermediates whereas bacteria associated with I. prostoma converted a limited amount of C18:2n-6 and CLA c9t11 to trans monoenes. C18:1t11 was not hydrogenated by either I. prostoma or its associated bacteria but was isomerized to C18:1c9. A phylogenetic analysis of clones originating from Butyrivibrio-specific PCR product was performed. This indicated that 71% of the clones from the endogenous and exogenous community clustered in close relationship with Lachnospira pectinoschiza. Additionally, the biohydrogenation activity of solid-associated bacteria (SAB) and liquid-associated bacteria (LAB) was examined and compared with the activity of the non-fractioned I. prostoma monofaunated rumen fluid (LAB 1 SAB). Both SAB and LAB were involved in rumen biohydrogenation of C18:2n-6. SAB fractions performed the full hydrogenation reaction to C18:0 while C18:1 fatty acids, predominantly C18:1t10 and C18:1t11, accumulated in the LAB fractions. SAB and LAB sequence analyses were mainly related to the genera Butyrivibrio and Pseudobutyrivibrio with 12% of the SAB clones closely related to the C18:0 producing B. proteoclasticus branch. In conclusion, this work suggests that I. prostoma and its associated bacteria play no role in C18:2n-6 biohydrogenation, while LAB convert C18:2n-6 to a wide range of C18:1 fatty acids and SAB produce C18:0, the end product of rumen lipid metabolism.

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Effects of Amount and Availability of Starch on Amylolytic Activity of Ruminal Solid-Associated Microorganisms

Nozière¹,

Michalet-Doreau²

1997

J. Sci. Food Agric.

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Three ruminally cannulated dry cows were used in an experiment designed as a Latin square to investigate the effects of amount and availability of starch on the amylolytic activity of ruminal solid‐associated microorganisms (SAM). Animals were fed twice daily a diet (7 kg DM day‐1) consisting of wheat straw, cocksfoot hay and ground barley in the ratios 10: 90: 0, 10: 60: 30 and 10: 30: 60. Nylon bags containing rapidly (barley) or slowly (maize) degradable cereal grains were incubated in the rumen. Enzymes of the SAM were extracted from rumen contents and bag residues, and amylolytic (amylase and α‐D‐glucosidase) activities were measured. The in situ degradation of starch was determined. Increasing the level of barley in the diet induced a linear increase in amylase activity of SAM in the rumen contents. In the bags, amylase activity and starch degradation rate were not modified by supplementation. High activity was observed more rapidly in bags containing barley, where starch is rapidly available, than in bags containing maize, where starch is protected by a resistant endosperm. These results suggest that amylolytic activity of SAM may depend on the amount of starch available to microorganisms. © 1997 SCI.

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The rumen protozoa

Cited by 199 publications

References 286 publications

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

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

Role of the protozoan Isotricha prostoma, liquid-, and solid-associated bacteria in rumen biohydrogenation of linoleic acid

Effects of Amount and Availability of Starch on Amylolytic Activity of Ruminal Solid-Associated Microorganisms

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