Factors affecting rumen methanogens and methane mitigation strategies
18 Apr 2009-World Journal of Microbiology & Biotechnology (Springer Netherlands)-Vol. 25, Iss: 9, pp 1557-1566
TL;DR: The present article aimed to cover comprehensively the different aspects of rumen methanogenesis such as the phylogeny of methanogens, their microbial ecology, factors affecting methane emission, mitigation strategies and need for further study.
Abstract: The rumen is a highly diverse ecosystem comprising different microbial groups including methanogens that consume a considerable part of the ruminant’s nutrient energy in methane production. The consequences of methanogenesis in the rumen may result in the low productivity and possibly will have a negative impact on the sustainability of the ruminant’s production. Since enteric fermentation emission is one of the major sources of methane and is influenced by a number of environmental factors, diet being the most significant one, a number of in vitro and in vivo trials have been conducted with different feed supplements (halogenated methane analogues, bacteriocins, propionate enhancers, acetogens, fats etc.) for mitigating methane emissions directly or indirectly, yet extensive research is required before reaching a realistic solution. Keeping this in view, the present article aimed to cover comprehensively the different aspects of rumen methanogenesis such as the phylogeny of methanogens, their microbial ecology, factors affecting methane emission, mitigation strategies and need for further study.
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TL;DR: The methanogens identified in the rumens of cattle and sheep, as well as a number of methane mitigation strategies that have been effective in vivo are described.
Abstract: Methanogens are the only known microorganisms capable of methane production, making them of interest when investigating methane abatement strategies. A number of experiments have been conducted to study the methanogen population in the rumen of cattle and sheep, as well as the relationship that methanogens have with other microorganisms. The rumen methanogen species differ depending on diet and geographical location of the host, as does methanogenesis, which can be reduced by modifying dietary composition, or by supplementation of monensin, lipids, organic acids, or plant compounds within the diet. Other methane abatement strategies that have been investigated are defaunation and vaccines. These mitigation methods target the methanogen population of the rumen directly or indirectly, resulting in varying degrees of efficacy. This paper describes the methanogens identified in the rumens of cattle and sheep, as well as a number of methane mitigation strategies that have been effective in vivo.
428 citations
Cites background from "Factors affecting rumen methanogens..."
...…15 August 2010; Revised 3 November 2010; Accepted 7 December 2010 Academic Editor: Reinhard Hensel Copyright © 2010 Sarah E. Hook et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction…...
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TL;DR: Essential oils appeared to be very promising compounds as they selectively reduced methane production and protein breakdown in both in vitro and in vivo studies, but in some studies, the use of EO as feed additives was accompanied with decreased feed degradability and lowered volatile fatty acid.
151 citations
Cites background from "Factors affecting rumen methanogens..."
...Methane emission also wastes 2–15% of the ingested energy, varying with the level of feed intake and diet composition (Kumar et al., 2009; Eckard et al., 2011)....
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...Methane is produced through a uniquemethanogenesis pathway involves three key coenzymes: coenzyme F420 (involved in electron transfer), coenzyme M (involved in transfer of methyl groups), and coenzyme B (involved in the final reaction of the pathway) (Kumar et al., 2009)....
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01 Jan 2015
TL;DR: This work focuses on the exploration and exploitation of rumen microbes, an underutilized niche for industrially important enzymes in a non-ruminant gut, and the implications for ruminant health and welfare.
Abstract: Part 1 - Overview of rumen and ruminants .- 1. Rumen Microbiology: An Overview.- 2. Rumen Microbial Ecosystem of Domesticated Ruminants.- 3. Domesticated Rare Animals (Yak, Mithun and Camel): Rumen Microbial Diversity.- 4. Wild Ruminants.- 5. Structure-and-function of a non-ruminant gut: a porcine model.- Part 2 - Rumen microbial diversity.- 6. Rumen bacteria.- 7. Rumen fungi.- 8. Rumen Protozoa.- 9. Ruminal viruses (Bacteriophages, Archaeaphages).- 10. Rumen Methanogens.- Part 3 - Rumen manipulation.- 11. Plant SecondaryMetabolites.- 12. Microbial feed additives.- 13. Utilization of organic acids to manipulate ruminal fermentation and improve ruminant productivity.- 14. Selective inhibition of harmful rumen microbes.- 15. Various 'Omics' approaches to understand and manipulate rumen microbial function.- Part 6 - Exploration and exploitation of rumen microbes.- 16. Rumen Metagenomics.- 17. Rumen: an underutilized niche for industrially important enzymes.- 18. Ruminal Fermentations to Produce Liquid and Gaseous Fuels.- 19. Commercial application of rumen microbial enzymes.- 20. Molecular characterization of Euryarcheal community within an anaerobic digester.- Part 5 - Intestinal disorders and rumen microbes.- 21. Acidosis in cattle.- 22. Urea/ ammonia metabolism in the rumen and toxicity in ruminants.- 23. Nitrate/ nitrite toxicity and possibilities of their use in ruminant diet.- Part 6 - Future prospects of rumen microbiology.- 24. The Revolution in Rumen Microbiology
112 citations
TL;DR: The construction of a methanogenic gene catalogue through these approaches will lead to understand the microbiome function, its relation with the host and feeds, and therefore, will form the basis of practically viable and eco-friendly methane mitigation approaches, while improving the ruminant productivity.
Abstract: The growing demand for sustainable animal production is compelling researchers to explore the potential approaches to reduce emissions of greenhouse gases from livestock that are mainly produced by enteric fermentation. Some potential solutions, for instance, the use of chemical inhibitors to reduce methanogenesis, are not feasible in routine use due to their toxicity to ruminants, inhibition of efficient rumen function or other transitory effects. Strategies, such as use of plant secondary metabolites and dietary manipulations have emerged to reduce the methane emission, but these still require extensive research before these can be recommended and deployed in the livestock industry sector. Furthermore, immunization vaccines for methanogens and phages are also under investigation for mitigation of enteric methanogenesis. The increasing knowledge of methanogenic diversity in rumen, DNA sequencing technologies and bioinformatics have paved the way for chemogenomic strategies by targeting methane producers. Chemogenomics will help in finding target enzymes and proteins, which will further assist in the screening of natural as well chemical inhibitors. The construction of a methanogenic gene catalogue through these approaches is an attainable objective. This will lead to understand the microbiome function, its relation with the host and feeds, and therefore, will form the basis of practically viable and eco-friendly methane mitigation approaches, while improving the ruminant productivity.
111 citations
Cites background from "Factors affecting rumen methanogens..."
...There have been reviews of methane abatement in recent times (Moss et al. 2000; Beauchemin et al. 2008; McAllister and Newbold 2008; Kumar et al. 2009; Eckard et al. 2010; Hook et al. 2010; Martin et al. 2010; Patra 2012; Wanapat et al. 2012), so this article will focus on the latest developments (phage therapy, immunization, chemogenomics approaches), possible future directions and challenges in mitigating enteric methane emissions from ruminants....
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...There have been reviews of methane abatement in recent times (Moss et al. 2000; Beauchemin et al. 2008; McAllister and Newbold 2008; Kumar et al. 2009; Eckard et al. 2010; Hook et al. 2010; Martin et al. 2010; Patra 2012; Wanapat et al. 2012), so this article will focus on the latest developments…...
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TL;DR: Co-occurrence analysis incorporating taxa from bacteria, ARF and archaea revealed syntrophic interactions both within and between microbial domains in response to change in diet as well as age of dairy cows, supporting the hypothesis that the rumen microbiome also matures with age to sustain the growing metabolic needs of the host.
Abstract: The rumen microbiome represents a complex microbial genetic web where bacteria, anaerobic rumen fungi (ARF), protozoa and archaea work in harmony contributing to the health and productivity of ruminants. We hypothesized that the rumen microbiome shifts as the dairy cow advances in lactations and these microbial changes may contribute to differences in productivity between primiparous (first lactation) and multiparous (≥second lactation) cows. To this end, we investigated shifts in the ruminal ARF and methanogenic communities in both primiparous (n = 5) and multiparous (n = 5) cows as they transitioned from a high forage to a high grain diet upon initiation of lactation. A total of 20 rumen samples were extracted for genomic DNA, amplified using archaeal and fungal specific primers, sequenced on a 454 platform and analyzed using QIIME. Community comparisons (Bray-Curtis index) revealed the effect of diet (P < 0.01) on ARF composition, while archaeal communities differed between primiparous and multiparous cows (P < 0.05). Among ARF, several lineages were unclassified, however, phylum Neocallimastigomycota showed the presence of three known genera. Abundance of Cyllamyces and Caecomyces shifted with diet, whereas Orpinomyces was influenced by both diet and age. Methanobrevibacter constituted the most dominant archaeal genus across all samples. Co-occurrence analysis incorporating taxa from bacteria, ARF and archaea revealed syntrophic interactions both within and between microbial domains in response to change in diet as well as age of dairy cows. Notably, these interactions were numerous and complex in multiparous cows, supporting our hypothesis that the rumen microbiome also matures with age to sustain the growing metabolic needs of the host. This study provides a broader picture of the ARF and methanogenic populations in the rumen of dairy cows and their co-occurrence implicates specific relationships between different microbial domains in response to diet and age.
108 citations
Cites background from "Factors affecting rumen methanogens..."
...Methane emitted from ruminants accounts for a loss of 2–12% of metabolizable energy intake, and also causes an environmental problem due its large global warming potential (Johnson and Johnson, 1995; Kumar et al., 2009)....
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References
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TL;DR: Phylogenetic analysis of the retrieved rRNA sequence of an uncultured microorganism reveals its closest culturable relatives and may, together with information on the physicochemical conditions of its natural habitat, facilitate more directed cultivation attempts.
9,017 citations
"Factors affecting rumen methanogens..." refers background in this paper
...Though most species have hitherto proven resistant to axenic culture (Amann et al. 1995), the following have been isolated from the rumen and are listed in Table 1....
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TL;DR: Knowing the factors that impact methane production can result in the development of mitigation strategies to reduce methane losses by cattle and implementation of these strategies should result in enhanced animal productivity and decreased contributions by cattle to the atmospheric methane budget.
Abstract: Increasing atmospheric concentrations of methane have led scientists to examine its sources of origin. Ruminant livestock can produce 250 to 500 L of methane per day. This level of production results in estimates of the contribution by cattle to global warming that may occur in the next 50 to 100 yr to be a little less than 2%. Many factors influence methane emissions from cattle and include the following: level of feed intake, type of carbohydrate in the diet, feed processing, addition of lipids or ionophores to the diet, and alterations in the ruminal microflora. Manipulation of these factors can reduce methane emissions from cattle. Many techniques exist to quantify methane emissions from individual or groups of animals. Enclosure techniques are precise but require trained animals and may limit animal movement. Isotopic and nonisotopic tracer techniques may also be used effectively. Prediction equations based on fermentation balance or feed characteristics have been used to estimate methane production. These equations are useful, but the assumptions and conditions that must be met for each equation limit their ability to accurately predict methane production. Methane production from groups of animals can be measured by mass balance, micrometeorological, or tracer methods. These techniques can measure methane emissions from animals in either indoor or outdoor enclosures. Use of these techniques and knowledge of the factors that impact methane production can result in the development of mitigation strategies to reduce methane losses by cattle. Implementation of these strategies should result in enhanced animal productivity and decreased contributions by cattle to the atmospheric methane budget.
2,251 citations
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01 Jan 2002TL;DR: The FAO's latest assessment of the long-term outlook for the world's food supplies, nutrition and agriculture is presented in this paper, where the projections cover supply and demand for the major agricultural commodities and sectors, including fisheries and forestry.
Abstract: This report is FAO's latest assessment of the long-term outlook for the world's food supplies, nutrition and agriculture. It presents the projections and the main messages. The projections cover supply and demand for the major agricultural commodities and sectors, including fisheries and forestry. This analysis forms the basis for a more detailed examination of other factors, such as nutrition and undernourishment, and the implications for international trade. The report also investigates the implications of future supply and demand for the natural resource base and discusses how technology can contribute to more sustainable development.
One of the report's main findings is that, if no corrective action is taken, the target set by the World Food Summit in 1996 (that of halving the number of undernourished people by 2015) is not going to be met. Nothing short of a massive effort at improving the overall development performance will free the developing world of its most pressing food insecurity problems. The progress made towards this target depends on many factors, not least of which are political will and the mobilization of additional resources. Past experience underlines the crucial role of agriculture in the development process, particularly where the majority of the population still depends on this sector for employment and income.
1,643 citations
TL;DR: In methanogens with cytochromes, the first and last steps in methanogenesis from CO2 are coupled chemiosmotically, whereas in methenogens without cyto Chromes, these steps are energetically coupled by a cytoplasmic enzyme complex that mediates flavin-based electron bifurcation.
Abstract: Most methanogenic archaea can reduce CO(2) with H(2) to methane, and it is generally assumed that the reactions and mechanisms of energy conservation that are involved are largely the same in all methanogens. However, this does not take into account the fact that methanogens with cytochromes have considerably higher growth yields and threshold concentrations for H(2) than methanogens without cytochromes. These and other differences can be explained by the proposal outlined in this Review that in methanogens with cytochromes, the first and last steps in methanogenesis from CO(2) are coupled chemiosmotically, whereas in methanogens without cytochromes, these steps are energetically coupled by a cytoplasmic enzyme complex that mediates flavin-based electron bifurcation.
1,620 citations
"Factors affecting rumen methanogens..." refers background in this paper
...Methanogens having cytochromes produce energy chemiosmotically compared to other methanogens where methanogenesis is energetically coupled to cytoplasmic enzymes (Thauer et al. 2008)....
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TL;DR: The most promising areas for future research for reducing methanogenesis are the development of new products/delivery systems for anti-methanogenic compounds or alternative electron acceptors in theRumen and reduction in protozoal numbers in the rumen.
Abstract: The aim of this paper is to review the role of methane in the global warming scenario and to examine the contribution to atmospheric methane made by enteric fermentation, mainly by ruminants. Agricultural emissions of methane in the EU-15 have recently been estimated at 10.2 million tonnes per year and represent the greatest source. Of these, approximately two-thirds come from enteric fermentation and one-third from livestock manure. Fermentation of feeds in the rumen is the largest source of methane from enteric fermentation and this paper considers in detail the reasons for, and the consequences of, the fact that the molar percentage of the different volatile fatty acids produced during fermentation influences the production of methane in the rumen. Acetate and butyrate promote methane production while propionate formation can be considered as a competitive pathway for hydrogen use in the rumen. The many alternative approaches to reducing methane are considered, both in terms of reduction per animal and reduction per unit of animal product. It was concluded that the most promising areas for future research for reducing methanogenesis are the development of new products/delivery systems for anti-methanogenic compounds or alternative electron acceptors in the rumen and reduction in protozoal numbers in the rumen. It is also stressed that the reason ruminants are so important to mankind is that much of the world's biomass is rich in fibre. They can convert this into high quality protein sources (i.e. meat and milk) for human consumption and this will need to be balanced against the concomitant production of methane.
1,172 citations
"Factors affecting rumen methanogens..." refers background in this paper
...Mitigation of methane may contribute to lowering the greenhouse effect that is a topical issue for the scientific community (Johnson and Johnson 1995; Moss et al. 2000 )....
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...Methane-oxidizing bacteria have been isolated from the rumen ( Moss et al. 2000 ) and other environments (Stock and McCleskey 1964) and have been identified based on molecular phylogeny (Heyer et al. 2002)....
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...Interest in the rumen methanogens has resulted from the fact that ruminants typically lose 2–15% of their ingested energy solely as methane ( Moss et al. 2000 )....
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...Furthermore, various feed supplements have been found to directly or indirectly reduce methane emissions, including halogenated methane analogues (Ungerfeld et al. 2004), bacteriocins (Lee et al. 2002), propionate enhancers, acetogens, immunization, genetic engineering, phage, fats and probiotics such as Saccharomyces cerevisiae, Aspergillus oryzae etc. (Boadi et al. 2004; Moss et al. 2000 )....
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...Reductive acetogenesis by acetogenic bacteria during hindgut fermentation (Demeyer and De Graeve 1991; Fonty et al. 2007a) could act as an alternative hydrogen sink and be exploited to reduce rumen methanogenesis ( Moss et al. 2000 )....
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