Nitroethane (NE), 2-nitroethanol (NEOH) and 2-nitro-1-propanol (NPOH) were investigated in order to determine their inhibitory effects on in vitro ruminal fermentation and methane (CH4) production of a hay-rich substrate (alfalfa hay: maize meal = 4:1, w/w). The rumen liquor collected from cannulated Holstein dairy cows was incubated at 39 °C for 72 h. The addition of NE, NEOH and NPOH slowed down the fermentation process and notably decreased molar CH4 proportion by 96.8, 96.4 and 35.0%, respectively. The abundance of total methanogen and methanogens from the order Methanobacteriales were all decreased with NE, NEOH and NPOH supplementation. Meanwhile, the nitrocompound addition reduced mcrA gene expression, coenzyme F420 and F430 contents. The correlation analysis showed that CH4 production was correlated positively with the population abundance of total methanogens, Methanobacteriales, mcrA gene expression, coenzyme contents of F420 and F430. The nitrocompound addition decreased acetate concentration and increased propionate and butyrate concentrations in the culture fluid. In summary, both NE and NEOH addition presented nearly the same inhibitory effectiveness on in vitro CH4 production; they were more effective than NPOH. The results of the current study provide evidence that NE, NEOH and NPOH can dramatically decrease methanogen population, mcrA gene expression and the coenzyme content of F420 and F430 in ruminal methanogenesis.

中文翻译：

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硝基化合物对体外瘤胃产甲烷的抑制作用模式：硝基乙烷、2-硝基乙醇和2-硝基-1-丙醇的比较

研究了硝基乙烷 (NE)、2-硝基乙醇 (NEOH) 和 2-硝基-1-丙醇 (NPOH)，以确定它们对体外瘤胃发酵和甲烷（CH4) 生产富含干草的基质（苜蓿干草：玉米粉 = 4:1，w/w）。从插管荷斯坦奶牛收集的瘤胃液在 39°C 下培养 72 小时。NE、NEOH 和 NPOH 的添加减慢了发酵过程并显着降低了摩尔 CH4比例分别为 96.8、96.4 和 35.0%。总产甲烷菌和产甲烷菌的丰度从序甲烷杆菌目NE、NEOH 和 NPOH 补充剂均降低。同时，硝基化合物的添加量减少mcr基因表达，辅酶F420和F430内容。相关分析表明，CH4产量与总产甲烷菌的种群丰度呈正相关，甲烷杆菌目,mcrA基因表达、辅酶含量F420和F430. 硝基化合物的添加降低了培养液中的乙酸盐浓度并增加了丙酸盐和丁酸盐的浓度。总之，NE 和 NEOH 添加都表现出几乎相同的抑制效果体外甲烷4生产; 它们比 NPOH 更有效。目前的研究结果提供了证据表明 NE、NEOH 和 NPOH 可以显着减少产甲烷菌的数量，mcr基因表达和辅酶含量F420和F430在瘤胃产甲烷中。