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Toyber I, Kumar R, Jami E. Rumen protozoa are a hub for diverse hydrogenotrophic functions. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13298. [PMID: 38961629 PMCID: PMC11222294 DOI: 10.1111/1758-2229.13298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Accepted: 05/08/2024] [Indexed: 07/05/2024]
Abstract
Ciliate protozoa are an integral part of the rumen microbial community involved in a variety of metabolic processes. These processes are thought to be in part the outcome of interactions with their associated prokaryotic community. For example, methane production is enhanced through interspecies hydrogen transfer between protozoa and archaea. We hypothesize that ciliate protozoa are host to a stable prokaryotic community dictated by specific functions they carry. Here, we modify the microbial community by varying the forage-to-concentrate ratios and show that, despite major changes in the prokaryotic community, several taxa remain stably associated with ciliate protozoa. By quantifying genes belonging to various known reduction pathways in the rumen, we find that the bacterial community associated with protozoa is enriched in genes belonging to hydrogen utilization pathways and that these genes correspond to the same taxonomic affiliations seen enriched in protozoa. Our results show that ciliate protozoa in the rumen may serve as a hub for various hydrogenotrophic functions and a better understanding of the processes driven by different protozoa may unveil the potential role of ciliates in shaping rumen metabolism.
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Affiliation(s)
- Ido Toyber
- Department of Ruminant Science, Institute of Animal SciencesAgricultural Research Organization, Volcani CenterRishon LeZionIsrael
- Department of Animal Sciencethe Hebrew University of JerusalemRehovotIsrael
| | - Raghawendra Kumar
- Department of Ruminant Science, Institute of Animal SciencesAgricultural Research Organization, Volcani CenterRishon LeZionIsrael
| | - Elie Jami
- Department of Ruminant Science, Institute of Animal SciencesAgricultural Research Organization, Volcani CenterRishon LeZionIsrael
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Ortiz-Chura A, Gere J, Marcoppido G, Depetris G, Cravero S, Faverín C, Pinares-Patiño C, Cataldi A, Cerón-Cucchi ME. Dynamics of the ruminal microbial ecosystem, and inhibition of methanogenesis and propiogenesis in response to nitrate feeding to Holstein calves. ACTA ACUST UNITED AC 2021; 7:1205-1218. [PMID: 34754962 PMCID: PMC8556761 DOI: 10.1016/j.aninu.2021.07.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 06/25/2021] [Accepted: 07/08/2021] [Indexed: 12/18/2022]
Abstract
It is known that nitrate inhibits ruminal methanogenesis, mainly through competition with hydrogenotrophic methanogens for available hydrogen (H2) and also through toxic effects on the methanogens. However, there is limited knowledge about its effects on the others members of ruminal microbiota and their metabolites. In this study, we investigated the effects of dietary nitrate inclusion on enteric methane (CH4) emission, temporal changes in ruminal microbiota, and fermentation in Holstein calves. Eighteen animals were maintained in individual pens for 45 d. Animals were randomly allocated to either a control (CTR) or nitrate (NIT, containing 15 g of calcium nitrate/kg dry matter) diets. Methane emissions were estimated using the sulfur hexafluoride (SF6) tracer method. Ruminal microbiota changes and ruminal fermentation were evaluated at 0, 4, and 8 h post-feeding. In this study, feed dry matter intake (DMI) did not differ between dietary treatments (P > 0.05). Diets containing NIT reduced CH4 emissions by 27% (g/d) and yield by 21% (g/kg DMI) compared to the CTR (P < 0.05). The pH values and total volatile fatty acids (VFA) concentration did not differ between dietary treatments (P > 0.05) but differed with time, and post-feeding (P < 0.05). Increases in the concentrations of ruminal ammonia nitrogen (NH3–N) and acetate were observed, whereas propionate decreased at 4 h post-feeding with the NIT diet (P < 0.05). Feeding the NIT diet reduced the populations of total bacteria, total methanogens, Ruminococcus albus and Ruminococcus flavefaciens, and the abundance of Succiniclasticum, Coprococcus, Treponema, Shuttlewortia, Succinivibrio, Sharpea, Pseudobutyrivibrio, and Selenomona (P < 0.05); whereas, the population of total fungi, protozoa, Fibrobacter succinogenes, Atopobium and Erysipelotrichaceae L7A_E11 increased (P < 0.05). In conclusion, feeding nitrate reduces enteric CH4 emissions and the methanogens population, whereas it decreases the propionate concentration and the abundance of bacteria involved in the succinate and acrylate pathways. Despite the altered fermentation profile and ruminal microbiota, DMI was not influenced by dietary nitrate. These findings suggest that nitrate has a predominantly direct effect on the reduction of methanogenesis and propionate synthesis.
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Affiliation(s)
- Abimael Ortiz-Chura
- Institute of Pathobiology, CICVyA National Institute of Agricultural Technology, IPVet, UEDD INTA-CONICET, Hurlingham, C1686, Argentina
| | - José Gere
- Engineering Research and Development Division, National Technological University (UTN), National Scientific and Technical Research Council (CONICET), Buenos Aires, C1179, Argentina
| | - Gisela Marcoppido
- Institute of Pathobiology, CICVyA National Institute of Agricultural Technology, IPVet, UEDD INTA-CONICET, Hurlingham, C1686, Argentina
| | - Gustavo Depetris
- Agricultural Experimental Station of Balcarce, National Institute of Agricultural Technology (INTA), Balcarce, B7620, Argentina
| | - Silvio Cravero
- Institute of Agrobiotechnology and Molecular Biology, IABIMO, National Institute of Agricultural Technology (INTA), National Scientific and Technical Research Council (CONICET), Hurlingham, C1686, Argentina
| | - Claudia Faverín
- Agricultural Experimental Station of Balcarce, National Institute of Agricultural Technology (INTA), Balcarce, B7620, Argentina
| | - Cesar Pinares-Patiño
- The Agribusiness Group, Lincoln University, PO Box 85016, Lincoln, 7674, New Zealand
| | - Angel Cataldi
- Institute of Agrobiotechnology and Molecular Biology, IABIMO, National Institute of Agricultural Technology (INTA), National Scientific and Technical Research Council (CONICET), Hurlingham, C1686, Argentina
| | - María E Cerón-Cucchi
- Institute of Pathobiology, CICVyA National Institute of Agricultural Technology, IPVet, UEDD INTA-CONICET, Hurlingham, C1686, Argentina
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Wenner BA, Wagner BK, St-Pierre NR, Yu ZT, Firkins JL. Inhibition of methanogenesis by nitrate, with or without defaunation, in continuous culture. J Dairy Sci 2020; 103:7124-7140. [PMID: 32600762 DOI: 10.3168/jds.2020-18325] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/29/2020] [Indexed: 02/02/2023]
Abstract
Within the rumen, nitrate can serve as an alternative sink for aqueous hydrogen [H2(aq)] accumulating during fermentation, producing nitrite, which ideally is further reduced to ammonium but can accumulate under conditions not yet explained. Defaunation has also been associated with decreased methanogenesis in meta-analyses because protozoa contribute significantly to H2 production. In the present study, we applied a 2 × 2 factorial treatment arrangement in a 4 × 4 Latin square design to dual-flow continuous culture fermentors (n = 4). Treatments were control without nitrate (-NO3-) versus with nitrate (+NO3-; 1.5% of diet dry matter), factorialized with normal protozoa (faunated, FAUN) versus defaunation (DEF) by decreasing the temperature moderately and changing filters over the first 4 d of incubation. We detected no main effects of DEF or interaction of faunation status with +NO3-. The main effect of +NO3- increased H2(aq) by 11.0 µM (+117%) compared with -NO3-. The main effect of +NO3- also decreased daily CH4 production by 8.17 mmol CH4/d (31%) compared with -NO3-. Because there were no treatment effects on neutral detergent fiber digestibility, the main effect of +NO3- also decreased CH4 production by 1.43 mmol of CH4/g of neutral detergent fiber degraded compared with -NO3-. There were no effects of treatment on other nutrient digestibilities, N flow, or microbial N flow per gram of nutrient digested. The spike in H2(aq) after feeding NO3- provides evidence that methanogenesis is inhibited by substrate access rather than concentration, regardless of defaunation, or by direct inhibition of NO2-. Methanogens were not decreased by defaunation, suggesting a compensatory increase in non-protozoa-associated methanogens or an insignificant contribution of protozoa-associated methanogens. Despite adaptive reduction of NO3- to NH4+ and methane inhibition in continuous culture, practical considerations such as potential to depress dry matter intake and on-farm ration variability should be addressed before considering NO3- as an avenue for greater sustainability of greenhouse gas emissions in US dairy production.
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Affiliation(s)
- B A Wenner
- Department of Animal Sciences, The Ohio State University, Columbus 43210.
| | - B K Wagner
- Department of Animal Sciences, The Ohio State University, Columbus 43210
| | - N R St-Pierre
- Department of Animal Sciences, The Ohio State University, Columbus 43210
| | - Z T Yu
- Department of Animal Sciences, The Ohio State University, Columbus 43210
| | - J L Firkins
- Department of Animal Sciences, The Ohio State University, Columbus 43210
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Villar ML, Hegarty RS, Clay JW, Smith KA, Godwin IR, Nolan JV. Dietary nitrate and presence of protozoa increase nitrate and nitrite reduction in the rumen of sheep. J Anim Physiol Anim Nutr (Berl) 2020; 104:1242-1255. [PMID: 32333622 DOI: 10.1111/jpn.13365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 03/12/2020] [Accepted: 03/15/2020] [Indexed: 01/18/2023]
Abstract
Nitrate ( NO 3 - ) supplementation is an effective methane (CH4 ) mitigation strategy for ruminants but may produce nitrite ( NO 2 - ) toxicity. It has been reported that rumen protozoa have greater ability for NO 3 - and NO 2 - reduction than bacteria. It was hypothesised that the absence of ruminal protozoa in sheep may lead to higher NO 2 - accumulation in the rumen and a higher blood methaemoglobin (MetHb) concentration. An in vivo experiment was conducted with defaunated (DEF) and faunated (FAU) sheep supplemented with 1.8% NO 3 - in DM. The effects of rumen protozoa on concentrations of plasma and ruminal NO 3 - and NO 2 - , blood MetHb, ruminal volatile fatty acid (VFA) and ruminal ammonia (NH3 ) were investigated. Subsequently, two in vitro experiments were conducted to determine the contribution of protozoa to NO 3 - and NO 2 - reduction rates in DEF and FAU whole rumen digesta (WRD) and its liquid (LIQ) and solid (SOL) fractions, incubated alone (CON), with the addition of NO 3 - or with the addition of NO 2 - . The results from the in vivo experiment showed no differences in total VFA concentrations, although ruminal NH3 was greater (p < .01) in FAU sheep. Ruminal NO 3 - , NO 2 - and plasma NO 2 - concentrations tended to increase (p < .10) 1.5 hr after feeding in FAU relative to DEF sheep. In vitro results showed that NO 3 - reduction to NH3 was stimulated (p < .01) by incoming NO 3 - in both DEF and FAU relative to CON digesta. However, adding NO 3 - increased (p < .05) the rate of NO 2 - accumulation in the SOL fraction of DEF relative to both fractions of FAU digesta. Results observed in vivo and in vitro suggest that NO 3 - and NO 2 - are more rapidly metabolised in the presence of rumen protozoa. Defaunated sheep may have an increased risk of NO 2 - poisoning due to NO 2 - accumulation in the rumen.
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Affiliation(s)
- María Laura Villar
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia.,Instituto Nacional de Tecnología Agropecuaria (INTA Bariloche), Bariloche, Argentina
| | - Roger Stephen Hegarty
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Jonathon William Clay
- School of Science and Technology, University of New England, Armidale, NSW, Australia
| | - Katherine Anne Smith
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Ian Robert Godwin
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - John Vivian Nolan
- School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
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Firkins JL, Yu Z, Park T, Plank JE. Extending Burk Dehority's Perspectives on the Role of Ciliate Protozoa in the Rumen. Front Microbiol 2020; 11:123. [PMID: 32184759 PMCID: PMC7058926 DOI: 10.3389/fmicb.2020.00123] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 01/20/2020] [Indexed: 01/22/2023] Open
Abstract
Dr. Burk Dehority was an international expert on the classification and monoculture of ruminal ciliated protozoa. We have summarized many of the advancements in knowledge from his work but also in his scientific way of thinking about interactions of ruminal ciliates with the entire rumen microbial community and animal host. As a dedication to his legacy, an electronic library of high-resolution images and video footage catalogs numerous species and techniques involved in taxonomy, isolation, culture, and ecological assessment of ruminal ciliate species and communities. Considerable promise remains to adapt these landmark approaches to harness eukaryotic cell signaling technology with genomics and transcriptomics to assess cellular mechanisms regulating growth and responsiveness to ruminal environmental conditions. These technologies can be adapted to study how protozoa interact (both antagonism and mutualism) within the entire ruminal microbiota. Thus, advancements and limitations in approaches used are highlighted such that future research questions can be posed to study rumen protozoal contribution to ruminant nutrition and productivity.
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Affiliation(s)
- Jeffrey L Firkins
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
| | - Zhongtang Yu
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
| | - Tansol Park
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
| | - Johanna E Plank
- Department of Animal Sciences, The Ohio State University, Columbus, OH, United States
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Meller RA, Wenner BA, Ashworth J, Gehman AM, Lakritz J, Firkins JL. Potential roles of nitrate and live yeast culture in suppressing methane emission and influencing ruminal fermentation, digestibility, and milk production in lactating Jersey cows. J Dairy Sci 2019; 102:6144-6156. [PMID: 31030922 DOI: 10.3168/jds.2018-16008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 03/05/2019] [Indexed: 12/11/2022]
Abstract
Concern over the carbon footprint of the dairy industry has led to various dietary approaches to mitigate enteric CH4 production. One approach is feeding the electron acceptor NO3-, thus outcompeting methanogens for aqueous H2. We hypothesized that a live yeast culture (LYC; Saccharomyces cerevisiae from Yea-Sacc 1026, Alltech Inc., Nicholasville, KY) would stimulate the complete reduction of NO3- to NH3 by selenomonads, thus decreasing the quantity of CH4 emissions per unit of energy-corrected milk production while decreasing blood methemoglobin concentration resulting from the absorbed intermediate, NO2-. Twelve lactating Jersey cows (8 multiparous and noncannulated; 4 primiparous and ruminally cannulated) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Cattle were fed diets containing 1.5% NO3- (from calcium ammonium nitrate) or an isonitrogenous control diet (containing additional urea) and given a top-dress of ground corn without or with LYC, with the fourth week used for data collection. Noncannulated cows were spot measured for CH4 emission by mouth using GreenFeed (C-Lock Inc., Rapid City, SD). The main effect of NO3- decreased CH4 by 17% but decreased dry matter intake by 10% (from 19.8 to 17.8 kg/d) such that CH4:dry matter intake numerically decreased by 8% and CH4:milk net energy for lactation production was unaffected by treatment. Milk and milk fat production were not affected, but NO3- decreased milk protein from 758 to 689 g/d. Ruminal pH decreased more sharply after feeding for cows fed diets without NO3-. Acetate:propionate was greater for cows fed NO3-, particularly when combined with LYC (interaction effect). Blood methemoglobin was higher for cattle fed NO3- than for those fed the control diet but was low for both treatments (1.5 vs. 0.5%, respectively; only one measurement exceeded 5%), indicating minimal risk for NO2- accumulation at our feeding level of NO3-. Although neither apparent organic matter nor neutral detergent fiber digestibilities were affected, apparent N digestibility had an interaction for NO3- × LYC such that apparent N digestibility was numerically lowest for diets containing both NO3- and LYC compared with the other 3 diets. Under the conditions of this study, NO3- mitigated ruminal methanogenesis but also depressed dry matter intake and milk protein yield. Based on the fact that few interactions were detected, LYC had a minimal role in attenuating negative cow responses to NO3- supplementation.
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Affiliation(s)
- R A Meller
- Department of Animal Sciences, The Ohio State University, Columbus 43210
| | - B A Wenner
- Department of Animal Sciences, The Ohio State University, Columbus 43210
| | - J Ashworth
- Department of Animal Sciences, The Ohio State University, Columbus 43210
| | - A M Gehman
- Alltech, 3031 Catnip Hill Pike, Nicholasville, KY 40356
| | - J Lakritz
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus 43210
| | - J L Firkins
- Department of Animal Sciences, The Ohio State University, Columbus 43210.
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Welty CM, Wenner BA, Wagner BK, Roman-Garcia Y, Plank JE, Meller RA, Gehman AM, Firkins JL. Rumen microbial responses to supplemental nitrate. II. Potential interactions with live yeast culture on the prokaryotic community and methanogenesis in continuous culture. J Dairy Sci 2019; 102:2217-2231. [PMID: 30639000 DOI: 10.3168/jds.2018-15826] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 11/27/2018] [Indexed: 12/21/2022]
Abstract
Nitrates have been fed to ruminants, including dairy cows, as an electron sink to mitigate CH4 emissions. In the NO3- reduction process, NO2- can accumulate, which could directly inhibit methanogens and possibly other microbes in the rumen. Saccharomyces cerevisiae yeast was hypothesized to decrease NO2- through direct reduction or indirectly by stimulating the bacterium Selenomonas ruminantium, which is among the ruminal bacteria most well characterized to reduce both NO3- and NO2-. Ruminal fluid was incubated in continuous cultures fed diets without or with NaNO3 (1.5% of diet dry matter; i.e., 1.09% NO3-) and without or with live yeast culture (LYC) fed at a recommended 0.010 g/d (scaled from cattle to fermentor intakes) in a 2 × 2 factorial arrangement of treatments. Treatments with LYC had increased NDF digestibility and acetate:propionate by increasing acetate molar proportion but tended to decrease total VFA production. The main effect of NO3- increased acetate:propionate by increasing acetate molar proportion; NO3- also decreased molar proportions of isobutyrate and butyrate. Both NO3- and LYC shifted bacterial community composition (based on relative sequence abundance of 16S rRNA genes). An interaction occurred such that NO3- decreased valerate molar proportion only when no LYC was added. Nitrate decreased daily CH4 emissions by 29%. However, treatment × time interactions were present for both CH4 and H2 emission from the headspace; CH4 was decreased by the main effect of NO3- until 6 h postfeeding, but NO3- and LYC decreased H2 emission up to 4 h postfeeding. As expected, NO3- decreased methane emissions in continuous cultures; however, contrary to expectations, LYC did not attenuate NO2- accumulation.
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Affiliation(s)
- C M Welty
- Department of Animal Sciences, The Ohio State University, 2029 Fyffe Ct., Columbus 43210
| | - B A Wenner
- Department of Animal Sciences, The Ohio State University, 2029 Fyffe Ct., Columbus 43210
| | - B K Wagner
- Department of Animal Sciences, The Ohio State University, 2029 Fyffe Ct., Columbus 43210
| | - Y Roman-Garcia
- Department of Animal Sciences, The Ohio State University, 2029 Fyffe Ct., Columbus 43210
| | - J E Plank
- Department of Animal Sciences, The Ohio State University, 2029 Fyffe Ct., Columbus 43210
| | - R A Meller
- Department of Animal Sciences, The Ohio State University, 2029 Fyffe Ct., Columbus 43210
| | - A M Gehman
- Alltech, 3031 Catnip Hill Pike, Nicholasville, KY 40356
| | - J L Firkins
- Department of Animal Sciences, The Ohio State University, 2029 Fyffe Ct., Columbus 43210.
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