Control of the synthesis of nitrite reductase in ruminal bacteria.

1.对瘤胃单胞菌硝酸还原酶进行了纯化，并对其基因进行了测序。研究了影响该基因转录的因素。2.瘤胃内具有还原硝酸盐和亚硝酸盐能力的瘤胃链霉菌的细胞数约占瘤胃链霉菌总数的10%。因此，刺激硝酸盐和亚硝酸盐还原菌株的生长是可取的。建议增加纤维消化，以抑制亚硝酸盐在瘤胃内的积累。3.筛选出一株还原亚硝酸盐能力较强的梭状芽孢杆菌。在体外瘤胃微生物区系中添加该菌，亚硝酸盐还原速率增加，甲烷产量降低。4.添加具有较高还原亚硝酸盐能力的琥珀酸Wollinella琥珀酸杆菌，亚硝酸盐还原速率增加，甲烷产量降低。在瘤胃微生物区系中添加乙醇可促进硝酸盐和亚硝酸盐还原。6.分离到一株具有较高还原亚硝酸盐能力的牛链球菌。作为控制牛链球菌发酵和生长的机制，全球分解代谢控制蛋白A、1，6-二磷酸果糖和LuxS自动诱导剂2的参与是重要的。

1.Nitrate reductase of Selenomonas ruminantium was purified, and its gene was sequenced. Factors affecting the transcription of the gene were examined.2.The cell number of S.ruminantium having the capacity to reduce nitrate and nitrite in the rumen was found to be about a 10 % of the total number of S.ruminantium. Therefore, it is desirable to stimulate the growth of nitrate- and nitrite-reducing strains. Augmentation of fiber digestion was suggested to suppress nitrite accumulation in the rumen.3.A species of Clostridium that has high capacity to reduce nitrite was isolated. Addition of the bacterium to the ruminal microbiota in vitro resulted in an increase in the rate of nitrite reduction and a decrease in methane production.4.Similarly, addition of Wollinella succinogenes that has high capacity to reduce nitrite increased the rate of nitrite reduction and decreased methane production. Further supplementation of nitrate and fumarate magnified the effects.5.Addition of ethanol to the ruminal microbiota stimulated nitrate and nitrite reduction.6.A strain of Streptococcus bovis that has high capacity to reduce nitrite was isolated. As mechanisms to control fermentation and growth in S.bovis, importance of the involvement of global catabolite control protein A, fructose-1,6-bisphosphate, and LuxS autoinducer 2 was shown.