现代分子生物学技术在瘤胃产甲烷菌研究中的应用

瘤胃产甲烷菌代谢产生的甲烷气体,既能引起饲料能量的损失,又能引起温室效应,因此成为当前的一个研究热点.了解瘤胃产甲烷菌菌群的组成及其多样性是对其菌群结构进行调控,并最终控制甲烷产生的基础.但由于产甲烷菌培养条件要求苛刻,迄今为止只有少数几种产甲烷菌得到分离培养.现代分子生物学的迅速发展和应用,突破了瘤胃微生物不可培养的限制,极大地推动了对产甲烷菌的研究.本文综述了现代分子生物学技术在瘤胃产甲烷菌研究中的应用进展情况,并对其发展前景作了展望.     

反刍动物甲烷的产生、测定及减排调控的研究

文章综述了反刍动物甲烷的产生机制和瘤胃内主要的产甲烷菌种类,并阐明了不同的产甲烷菌的甲烷合成底物及甲烷合成途径。文章还阐明了反刍动物甲烷产量的测定方法以及减排措施。     

瘤胃甲烷菌与其他瘤胃微生物关系和测定技术研究进展

甲烷菌是可生存于瘤胃中的一种古细菌,通过利用瘤胃代谢产生的物质如:CO_2、H_2合成甲烷。反刍动物产生的甲烷不仅会加剧温室效应的产生,还会导致饲料中能量的损失,因此对产甲烷菌进行调控的研究日益增多。产甲烷菌在瘤胃微生物中占有重要的地位,与其他的瘤胃微生物存在促进或抑制的不同关系,因此需要对甲烷菌展开更为系统的研究。论文对瘤胃甲烷菌的种类、未培养技术的应用和甲烷菌与其他瘤胃微生物之间的关系进行概述,旨在为研究甲烷菌以减少反刍动物甲烷排放量提供参考。     

瘤胃古菌C簇研究进展

甲烷常被认为是仅次于二氧化碳的第二大温室气体。反刍动物是甲烷的主要排放来源之一,其甲烷排放量占全球甲烷排放总量的15%~25%。因此,反刍动物甲烷排放日益得到重视。反刍动物体内的甲烷主要由产甲烷菌利用二氧化碳和氢生成。瘤胃古菌C簇(Rumen Cluster C,RCC)是瘤胃产甲烷菌的重要组成部分,目前对其了解尚少。为进一步推动对RCC的研究,文章就RCC的发现、分布、生物学特性和分子水平的研究做一叙述。     

精原干细胞移植相关技术研究进展

精原干细胞的分离培养及移植等相关技术对于雄性动物不育、精子发生机理的研究及转基因新技术的建立都具有重要意义.虽然小鼠精原干细胞的生物学特性已经研究得较为清晰,并建立了较为成熟的分离、纯化、培养技术体系,其受体制备和移植技术也较为成熟,但是,技术效率仍然很低.对小鼠精原干细胞生物学特性、分离培养及受体制备与移植方法的分析总结,将对于细胞制备最佳时机的确定、已有精原干细胞分离纯化、培养和受体准备及移植方法的改进提高起到重要的推动作用,也为今后大型动物的相关研究指明了方向.     

3-硝基酯-1-丙醇抑制反刍动物瘤胃甲烷排放的机理及对动物的影响

反刍动物甲烷的排放既造成饲料能量的浪费,也会加剧全球变暖作用。在反刍动物瘤胃中,产甲烷菌主要利用二氧化碳转化产生甲烷。产甲烷菌转化二氧化碳的最后一步反应需要甲基辅酶M还原酶参与,3-硝基酯-1-丙醇(3-nitrooxypropanol,3-NOP)是一种甲基辅酶M类似物,能与辅酶B结合,从而减少甲基辅酶M与辅酶B结合生成甲烷,因此3-NOP能有效地降低瘤胃甲烷的产生。本文旨在阐明3-NOP抑制反刍动物瘤胃甲烷产生的机制以及对反刍动物生产的影响。     

瘤胃微生物区系对调控产甲烷菌的相关影响

反刍动物瘤胃所产生的甲烷不仅导致饲料中能量的浪费,而且还增加了大气中温室气体甲烷浓度。文章对瘤胃产甲烷菌的分类、现代分子分析方法在甲烷中的应用、产甲烷菌在瘤胃微生物区系的相互关系及近期基于氢离子调控对产甲烷菌的影响等方面进行阐述,为减少甲烷排放提供新的思路和方向。     

鸟岛湿地土壤产甲烷菌群落对不同降水梯度的响应

产甲烷菌在湿地CH4排放过程中发挥着重要作用,降水格局的改变已经并将持续影响湿地生态系统的结构与功能,进而对湿地CH4排放过程产生影响。本研究以青海湖鸟岛湖滨湿地为研究对象,设置5个降水梯度处理,并利用mcrA扩增子测序技术对土壤产甲烷菌进行检测,探究鸟岛土壤产甲烷菌群落特征对不同降水梯度的响应。结果表明,鸟岛土壤产甲烷菌群落的优势菌目为甲烷微菌目(Methanomicrobiales)、甲烷八叠球菌目(Methanosarcinales)和甲烷杆菌目(Methanobacteriales)。FAPROTAX功能预测显示土壤中氢营养型产甲烷菌占优势,由此推测H2/CO2还原为鸟岛土壤CH4产生的主要途径。LEfSe分析表明,5个降水梯度共存在31个差异菌群,以增雨50%处理下差异菌群数量最多,从目水平到种水平共有10个差异菌群。整体而言,鸟岛土壤产甲烷菌的群落多样性较为稳定,而群落结构对降水变化的响应较为敏感,部分菌群的相对丰度发生了显著变化(P <0.05)。研究结果可为预测降水变化对鸟岛湿地土壤碳循环的影响提供一定的参考依据。     

高通量测序技术在瘤胃产甲烷菌群研究中的应用

瘤胃产甲烷菌代谢产生的甲烷气体不仅会造成动物消化能的损失,而且增加温室效应,是当前的一个研究热点。高通量测序技术具有诸多优越性,其在瘤胃产甲烷菌研究中的迅速应用,使研究者不仅能够对反刍动物瘤胃产甲烷菌系统分类,还能深入分析瘤胃产甲烷菌群落结构和多样性,有助于系统开展反刍动物瘤胃产甲烷菌的研究。文章综述了高通量测序的优点及其在反刍动物瘤胃产甲烷菌群研究中的应用进展,为研究甲烷菌群产生甲烷的机制提供参考。     

翻堆对蛋鸡粪堆肥甲烷排放的影响

采用蛋鸡粪和锯末堆肥,研究不同翻堆频率对堆肥甲烷排放量的影响。结果表明,在40d的堆肥过程中,翻堆频率为4次/d、2次/d、1次/d、1次/3d、1次/6d和不翻堆时,甲烷排放总量分别为28.60L、50.07L、70.85L、76.48L、90.74L和59.33L,与不翻堆相比,高翻堆频率(4次/d、2次/d)降低了甲烷排放总量,低翻堆频率(1次/3d、1次/6d)增加甲烷的排放总量。高翻堆频率显著降低产甲烷菌的多样性指数和产甲烷菌的总量,而低翻堆频率显著增加了产甲烷菌的总量。因此,不同翻堆频率可能是通过影响堆体氧气含量以及产甲烷菌多样性和总量来改变甲烷排放总量。     

Rumen methanogens and mitigation of methane emission by anti-methanogenic compounds and substances

Methanogenic archaea reside primarily in the rumen and the lower segments of the intestines of ruminants, where they utilize the reducing equivalents derived from rumen fermentation to reduce carbon dioxide, formic acid, or methylamines to methane(CH_4). Research on methanogens in the rumen has attracted great interest in the last decade because CH_4 emission from ruminants contributes to global greenhouse gas emission and represents a loss of feed energy. Some DNA-based phylogenetic studies have depicted a diverse and dynamic community of methanogens in the rumen. In the past decade, researchers have focused on elucidating the underpinning that determines and affects the diversity, composition, structure, and dynamics of methanogen community of the rumen. Concurrently, many researchers have attempted to develop and evaluate interventions to mitigate enteric CH_4 emission. Although much work has been done using plant secondary metabolites, other approaches such as using nitrate and 3-nitrooxy propanol have also yielded promising results. Most of these antimethanogenic compounds or substances often show inconsistent results among studies and also lead to adverse effects on feed intake and digestion and other aspects of rumen fermentation when fed at doses high enough to achieve effective mitigation. This review provides a brief overview of the rumen methanogens and then an appraisal of most of the antimethanogenic compounds and substances that have been evaluated both in vitro and in vivo. Knowledge gaps and future research needs are also discussed with a focus on methanogens and methane mitigation.     

反刍动物甲烷排放量营养调控技术的研究进展

本文通过研究甲烷产生的机理,阐述降低反刍动物瘤胃内甲烷的产量的调控方法,旨在为缓解温室效应、减少反刍动物瘤胃发酵的能量损失,找到一项重要的反刍动物绿色营养调控技术提供理论参考依据.     

Dietary sources and their effects on animal production and environmental sustainability

Animal agriculture has been an important component in the integrated farming systems in developing countries. It serves in a paramount diversified role in producing animal protein food, draft power, farm manure as well as ensuring social status-quo and enriching livelihood. Ruminants are importantly contributable to the well-being and the livelihood of the global population. Ruminant production systems can vary from subsistence to intensive type of farming depending on locality, resource availability,infrastructure accessibility, food demand and market potentials. The growing demand for sustainable animal production is compelling to researchers exploring the potential approaches to reduce greenhouse gases(GHG) emissions from livestock. Global warming has been an issue of concern and importance for all especially those engaged in animal agriculture. Methane(CH_4) is one of the major GHG accounted for at least 14% of the total GHG with a global warming potential 25-fold of carbon dioxide and a 12-year atmospheric lifetime. Agricultural sector has a contribution of 50 to 60% methane emission and ruminants are the major source of methane contribution(15 to 33%). Methane emission by enteric fermentation of ruminants represents a loss of energy intake(5 to 15% of total) and is produced by methanogens(archae) as a result of fermentation end-products. Ruminants' digestive fermentation results in fermentation end-products of volatile fatty acids(VFA), microbial protein and methane production in the rumen. Rumen microorganisms including bacteria, protozoa and fungal zoospores are closely associated with the rumen fermentation efficiency. Besides using feed formulation and feeding management, local feed resources have been used as alternative feed additives for manipulation of rumen ecology with promising results for replacement in ruminant feeding. Those potential feed additive practices are as follows: 1) the use of plant extracts or plants containing secondary compounds(e.g., condensed tannins and saponins) such as mangosteen peel powder, rain tree pod; 2) plants rich in minerals, e.g., banana flower powder; and 3) plant essential oils, e.g., garlic, eucalyptus leaf powder, etc. Implementation of the-feed-system using cash crop and leguminous shrubs or fodder trees are of promising results.     

瘤胃甲烷生成过程中微生物之间的相互关系

反刍动物瘤胃含有甲烷菌,是主要的甲烷(methane,CH4)排放源,甲烷菌利用饲料发酵过程中生成的氢和CO2作为主要的电子受体和供体通过还原反应生成甲烷,在瘤胃功能性生态生境(niche)中发挥重要作用.除甲烷菌以外,其他瘤胃微生物也影响甲烷产量.瘤胃微生物总体来说可分为产氢微生物(hydrogenogens)和耗氢...     

Comparison of emission estimates for non‐CO2 greenhouse gases from livestock and poultry in Korea from 1990 to 2010

It has often been claimed that non‐carbon dioxide greenhouse gases (NCGGs), such as methane, nitrous oxide and fluorinated greenhouse gases, are significant contributors to climate change. Here we nvestigate emission estimates of methane and nitrous oxide from livestock and poultry production, which is recognized as a major source of those NCGGs, in Korea over the period of 1990 through 2010. Based on the data on livestock and poultry populations, emission estimates of methane and nitrous oxide are first derived based on the Tier 1 approach. Then, the Tier 2 approach is adopted to obtain emission estimates of methane and nitrous oxide from cattle, which are known to be the largest sources of these NCGGs and account for about 70% of emissions from livestock and poultry in Korea. The result indicates that the Tier 2 estimates of methane and nitrous oxide emissions from enteric fermentation and manure management are significantly different from the Tier 1 estimates over the analysis period.     

氮输入对土壤甲烷产生、氧化和传输过程的影响及其机制

随着人为氮输入的增加,外源氮成为影响土壤甲烷产生、氧化和传输过程的重要因素。土壤甲烷排放受氮素有效性的调节,氮输入会改变土壤初始环境和甲烷排放规律,最终影响甲烷排放量。综述了氮输入对土壤甲烷产生、氧化和传输过程的影响及机制。研究表明,1)氮输入对甲烷排放通量的影响存在促进、抑制和不显著3种情况,这主要是甲烷产生、氧化和传输过程的变化引起的;2)氮输入对甲烷产生过程的影响受产甲烷底物和产甲烷微生物活性的控制,氮输入通过增加土壤有机碳的含量为甲烷产生提供了丰富的底物,同时底物理化性质和植被覆盖度的变化使得这种影响复杂化,氮输入既可促进又可抑制产甲烷菌的活性,并且这种作用受氮形态的影响;3)氮输入对甲烷氧化过程的影响主要是通过刺激或抑制甲烷氧化菌的活性实现的,氮形态的不同也使得这种变化更为复杂;4)氮输入对甲烷传输过程的影响主要受植物通气组织的数量以及传输效率的控制,并且在不同生态系统这种控制作用差异较大。综上所述,氮输入对土壤甲烷产生、氧化和传输过程的影响及机制具有明显的复杂性和不确定性,今后研究中应综合考虑氮输入对甲烷排放关键过程的影响,并侧重于探讨氮输入对相关微生物群落结构、丰度和活性的影响,同时注重对各个生态系统的协同研究,确定氮输入影响下各个生态系统对全球甲烷排放的贡献率。     

Effects of tea saponins on rumen microbiota,rumen fermentation,methane production and growth performance—a review

Reducing methane emission from ruminant animals has implications not only for global environmental protection but also for efficient animal production. Tea saponins (TS) extracted from seeds, leaves or roots of tea plant are pentacyclic triterpenes. They have a lasting antiprotozoal effect, but little effect on the methanogen population in sheep. There was no significant correlation between the protozoa counts and methanogens. The TS decreased methanogen activity. It seems that TS influenced the activity of the methanogens indirectly via the depressed ciliate protozoal population. The TS addition decreased fungal population in the medium containing rumen liquor in in vitro fermentation, but no such effect was observed in the rumen liquor of sheep fed TS. Tea saponins had a minor effect on the pattern of rumen fermentation and hence on nutrient digestion. When added at 3 g/day in diets, TS could improve daily weight gain and feed efficiency in goats. No positive associative effect existed between TS and disodium fumarate or soybean oil on methane suppression. Inclusion of TS in diets may be an effective way for improving feed efficiency in ruminants.     

Effect of antibiotics, 2-bromoethanesulfonic acid and pyromellitic diimide on methanogenesis in rumen ciliate cultures in vitro.

The effects of penicillin G, streptomycin, chloramphenicol, 2-bromoethanesulfonic acid and pyromellitic diimide on total gas, methane, volatile fatty acid production and food degradability after 24 h of incubation in vitro were investigated in the cultures of two rumen ciliates. The inocula of both rumen ciliates Entodinium caudatum and Epidinium ecaudatum were used at a volume of 34 ml into the 50 ml glass syringes together with the feed and compounds tested. Despite penicillin G--streptomycin treatment methane production in both cultures was significantly decreased by the inhibitors for Epidinium ecaudatum. Methane production of the bacterial fraction of both protozoan species was significantly lower than in the whole cultures. No epifluorescence of methanogens on (or in) the cells of Entodinium caudatum was observed in contrast to Epidinium with which strong epifluorescence of methanogens on the cell surface was detected. Microscopic observation could indicate that the methane production by Entodinium caudatum was probably caused by their intracellular methanogenic activity, while methane production by Epidinium ecaudatum could be related to both the methanogenic bacterial fraction from their external surface and probably also to intracellular activity. Decreased feed degradability and differences in the fermentation end products accompanied the inhibition of methanogenesis in both in vitro cultures. Entodinium caudatum appeared to be more sensitive than Epidinium ecaudatum to the compounds tested.     

过二硫酸盐提升奶牛养殖废水厌氧消化产甲烷性能研究

厌氧消化是实现奶牛场养殖废水资源化、无害化的常见处理方法,而传统厌氧消化的水解效率低,是影响厌氧消化推广应用的主要限制因素。结果表明,通过投加适量过二硫酸盐（Perdisulfate, PDS）能够有效提升奶牛养殖废水产甲烷效果与沼液的植物可利用性。在PDS投加量3.4 g/L时,产甲烷量提升最为明显,相较于未投加PDS的对照处理组,甲烷产量提升了130.00%。进一步对PDS提升厌氧消化产甲烷机理进行研究,结果表明,PDS投加能有效提高挥发性脂肪酸（Volatile Fatty Acids,VFAs）产量,其中乙酸产量的提高有利于乙酸型产甲烷过程。对试验样品的高通量测序证实了PDS处理提高了乙酸型产甲烷菌的相对丰度,PDS促进乙酸型产甲烷过程是提高甲烷产量的重要原因。