Effect of monensin withdrawal on rumen fermentation,methanogenesis and microbial populations in cattle

This study was designed to obtain information on the residual influence of dietary monensin on ruminant fermentation, methanogenesis and bacterial population. Three ruminally cannulated crossbreed heifers (14 months old, 363 ± 11 kg) were fed Italian ryegrass straw and concentrate supplemented with monensin for 21 days before sampling. Rumen fluid samples were collected for analysis of short chain fatty acid (SCFA) profiles, monensin concentration, methanogens and rumen bacterial density. Post‐feeding rumen fluid was also collected to determine in vitro gas production. Monensin was eliminated from the rumen fluid within 3 days. The composition of SCFA varied after elimination of monensin, while total production of SCFA was 1.78 times higher than on the first day. Methane production increased 7 days after monensin administration ceased, whereas hydrogen production decreased. The methanogens and rumen bacterial copy numbers were unaffected by the withdrawal of monensin.     

氨胁迫对猪粪厌氧消化性能的影响

以猪粪为原料,采用批式试验方法,研究不同氨氮添加量(0、400、800、1600、2400、3200、4000 mg·L^-1)对厌氧消化产气效果的影响.结果表明:随着氨氮添加量的增加,总产气量和CH₄产率均呈现先升高后降低的变化趋势,氨氮添加量 ≥2400 mg·L^-1时,厌氧消化过程受到显著抑制;不同处理中猪粪挥发性固体(VS)的CH₄产率分别为328.5、338.1、323.2、304.9、276.2、124.9、56.1 mL·g^-1.氨氮添加量为0~800 mg·L^-1时,最大VS产CH₄速率分别为18.3、18.4、17.1 mL·g^-1·d^-1;氨氮添加量为2400 mg·L^-1时,产气高峰推迟,产CH₄速率明显降低;氨氮添加量 ≥400 mg·L^-1时,厌氧消化30 d底物的生物转化产CH₄效率随氨氮添加量的增加逐渐降低,分别为56.7%、54.5%、52.4%、30.6%、1.6%和1.3%;氨氮添加量为400~2400 mg·L^-1时,乙酸利用型产甲烷菌Methanosaeta的相对丰度总体随氨氮质量浓度的增加而降低,而氢利用型产甲烷菌Methanosarcina和Methanococcus具有相反的变化规律.     

Analysis of methanogenic archaeal communities of rumen fluid and rumen particles from Korean black goats

Molecular diversity of methanogens in the rumen of Korean black goats was investigated with 16S rRNA gene clone libraries using methanogen‐specific primers. The libraries were composed of rumen fluid‐associated methanogens (FAM) and rumen particle‐associated methanogens (PAM) from rumen‐fistulated Korean black goats. Among the 141 clones of the FAM library, the sequences were mostly related to two phyla, the Methanobacteriaceae family (77.3%) and the Thermoplasmatales family (22.7%); and among the 68 clones of the PAM library, sequences were also mainly clustered in the two phyla, the Thermoplasmatales family (63.24%) and the Methanobacteriaceae family (35.29%). Most of the sequenced clones in the two libraries were closely related to uncultured methanogenic archaeon. Quantitative real‐time PCR revealed that PAM (8.97 log 10) had significantly higher (P < 0.01) density of methanogens by the methanogenic 16S rRNA gene copies than FAM (7.57 log 10). The two clone libraries also showed difference in Shannon index (FAM library 1.70 and PAM library 1.59) and Chao 1 estimator (FAM library 18 and PAM library 17 operational taxonomic units). Apparent differences found in the microbial community from the two 16S rRNA gene libraries could be a result of such factors as the chemical and physical nature of the target material surface, types or component of diets, the interaction between the methanogens and other microbes, and age of the experimental goats.     

A short note on linkage between the β- and κ-caseins in the Churra and Manchega ovine breeds

Abstract

The aim of this study was to evaluate the effect of Mentha piperita L. (MP) dried leaves on the in vitro rumen methanogenesis and fermentation. It was found that after 24 hours of incubations, addition of 16.34 and 23.35 mg of MP to the 233.3 mg of substrate significantly decreased methane emission by 41.52 and 15.51%, respectively. Simultaneously, the MP supplementation exerted no effect on the dry matter digestibility and volatile fatty acid profile. Addition of MP to the ruminants' diet inhibits the methane production without altering the basic parameters of rumen fermentation.     

pH调控对瘤胃液接种稻秸厌氧消化中水解菌及产甲烷菌的影响

为了研究pH值调控对瘤胃液接种厌氧消化体系的影响,在半连续条件下考察了稻秆水解和产甲烷特性,并分别利用相对定量PCR(Q-PCR)和Mi Seq高通量测序技术分析了微生物菌群的变化。结果表明:有机负荷为1.5、3.5 g·L-1·d-1和7 g·L-1·d-1时,调控体系中甲烷产率分别比对照提高了1.98、1.99倍和1.53倍;沼气中的甲烷含量明显提高(P0.05),在24%~32%之间变动。pH调控使乙酸和丙酸之间比例逐渐增大,体系中pH值维持在6.24~7.77之间,适宜稻秸产甲烷代谢;滤纸酶和羧甲基纤维素酶活性呈增加趋势。厌氧消化后GH 5水解菌群结构变化明显,梭状芽孢杆菌属(Clostridium)占主导地位,瘤胃球菌属(Ruminococcus)相对丰度提高了12.47倍;来源于瘤胃的纤维杆菌属(Fibrobacter)从体系中消逝。甲烷短杆菌属(Methanobrevibacter)相对丰度提高到3.73%,同时甲烷八叠球菌属(Methanosarcina)相对丰度增加。研究表明,pH调控体系通过强化水解和产甲烷菌活性提高了稻秸厌氧消化的效率。     

微量金属元素对甲烷菌激活作用的动力学研究

本文以血清瓶为反应器,以醛酸钙为基质,通过厌氧批量试验从动力学和角度研究了微量金属元素Fe、Co、Ni对甲烷菌的激活作用。结果表明,加入微量金属元素Fe、Co、Ni能有效缩短厌氧消化反应时间,提高基质降解率和产气速率。     

Suppression of Methane Production via the Promotion of Fe2+ Oxidation in Paddy Fields

ABSTRACT

Methane is a greenhouse gas, mainly generated from paddy fields and lakes by methanogens using hydrogen and acetic acid as substrates. In anaerobic environments with adequate Fe³⁺, iron-reducing microorganisms utilize these substrates, thus suppressing methane generation. We promoted Fe²⁺ oxidation to Fe³⁺ by physically stirring paddy soil and using a chelating agent (nitrilotriacetic acid; NTA) to evaluate the feasibility of the suppression of methane generation using Fe³⁺-reducing bacteria. Under anaerobic conditions, Fe³⁺ reduction to Fe²⁺ began immediately in the slurry made by adding water into air-dried paddy soil. Methane generation began on the 6th day when most Fe³⁺ was reduced. Under anaerobic conditions for 10 days followed by aerobic conditions, Fe²⁺ oxidation hardly progressed under static conditions. On stirring the slurry, Fe²⁺ oxidation progressed over 12 h (67% Fe²⁺ oxidized to Fe³⁺). When NTA was added under anaerobic conditions followed by stirring under aerobic conditions, Fe²⁺ oxidation was promoted further. The idea of physical stirring of paddy soil in the actual environment was derived from the effects of paddy soil stirring by ducks in interrelated rice–duck farming. In such farming, paddy soil contains more Fe³⁺ in its surface water compared with normal farming, resulting in suppressed methane generation.     

瘤胃总甲烷菌实时荧光定量PCR方法的构建

试验构建了瘤胃总甲烷菌实时荧光绝对定量PCR的标准品及标准曲线用于总甲烷菌的定量测定,并提取瘤胃微生物总DNA, 以甲烷菌特异性引物进行PCR扩增, 回收纯化PCR产物,与pBS-T载体连接并转化到大肠杆菌,再用氨苄西林培养基筛选阳性重组质粒, 提取含目的片段质粒DNA, 通过PCR及测序鉴定重组质粒.根据OD值确定浓度, 将梯度稀释的质粒作为模板, 进行荧光定量PCR反应并作出标准曲线.结果表明: 所构建的标准曲线具有很高的相关性(R2=0.992), 并获得了高扩增效率产物.     

利用分子生物技术对厌氧颗粒污泥中微生物种群结构的研究

利用F ISH、RTQ-PCR和DGGE等分子生物技术对厌氧产甲烷颗粒污泥中微生物种群的多样性、空间分布和定量关系进行研究,并对其中的优势古细菌进行系统发育分析。结果表明:颗粒污泥中真细菌主要分布在颗粒污泥外层,古细菌则主要分布在内层;古细菌含量低于真细菌,但有逐渐增多的趋势;随着反应器有机负荷的增加以及运行时间的延长,真细菌种群结构相对稳定,而古细菌种群结构则发生了较明显变化,其中占优势的古细菌种类逐渐减少,主要包括甲烷微粒菌(M ethanocorpuscu lum)、甲烷杆菌(M ethanobacter ium)和甲烷髦毛菌(M ethanosaeta)等。     

PCR-DGGE技术在水牛瘤胃产甲烷菌多样性分析中的应用

【目的】分析水牛瘤胃产甲烷菌的多样性,为更好地了解水牛瘤胃产甲烷菌提供科学依据。【方法】采集16头广西本地沼泽型水牛瘤胃内容物,提取总DNA,利用产甲烷菌的通用引物扩增16SrRNA基因序列进行DGGE分析,并对DGGE凝胶上7条优势条带进行回收克隆测序。【结果】共获得9条序列（5条为古菌序列、4条为非古菌序列）,5条古菌序列中有3条与甲烷短杆菌（Methanobrevibacter）的同源性高达99%、1条与甲烷短杆菌的同源性达98%、1条与广古菌门（Euryarchaeota）热原体目（Thermoplasmatales）的同源性达98%;而4条非古菌序列分别属于拟杆菌（Bac-teroidetes）、厚壁菌（Firmicutes）、变形菌门（Proteobacteria）,且彼此间同源性较小。【结论】通过PCR-DGGE技术可以较好地分析水牛瘤胃产甲烷菌的多样性。