Alternative schemes of butyrate production in Butyrivibrio fibrisolvens and their relationship to acetate utilization, lactate production, and phylogeny
Alternative schemes of butyrate production in Butyrivibrio fibrisolvens and their relationship to acetate utilization, lactate production, and phylogeny
复制标题
DOI：
10.1007/s002030050717
复制
发表时间：
1999-04-01
影响因子：
2.8
通讯作者：
Russell, JB
中科院分区：
文献类型：
--
作者：
Diez-Gonzalez, F;Bond, DR;Russell, JB
溶纤维丁酸弧菌菌株D1和A38产生很少的乳酸，但菌株49将其高达75%的葡萄糖转化为乳酸。菌株49的乳酸脱氢酶活性比菌株D1或A38高10倍，该活性被1，6-二磷酸果糖刺激，并且具有6.25的最适pH。然而，果糖1，6-二磷酸或pH调节菌株39中乳酸产生的作用与观察结果相矛盾，即非常低浓度（< 0.2 mM）的果糖1，6-二磷酸产生最大活性，并且当pH降低时，连续培养不会产生额外的乳酸。菌株49的乳酸生产明显受到生长培养基中乙酸盐的抑制。当菌株49补充有少至5 mM乙酸盐时，乳酸盐产量显著降低，并且大部分葡萄糖转化为丁酸盐。菌株49不具有丁酸激酶活性，但它具有丁酰辅酶A/乙酸辅酶A转移酶，其使用乙酸作为受体将丁酰辅酶A直接转化为丁酸。该转移酶对乙酸具有低亲和力（Km为5 mM），这一特性解释了乙酸对生长和丁酸形成的刺激作用。菌株D1和A38具有丁酸激酶，但不具有丁酰-CoA/乙酸CoA转移酶，并且呼吁这种差异可以解释缺乏乙酸刺激和乳酸产生。根据这些结果，不太可能是B。解纤蛋白对瘤胃乳酸的库有显著贡献。由于菌株49的近缘菌株（基于16 S rRNA序列分析的菌株Nor 37、PI-7、VV 1和OB 156）都具有相同的丁酸产生方法，因此丁酰CoA/乙酸CoA转移酶可能是系统发育特征。我们获得了产生大量乳酸并具有丁酰辅酶A/乙酸辅酶A转移酶活性的菌株B835（NCDO 2398）的培养物，但该菌株先前已基于16 S rRNA序列分析与菌株A38和DI分组。B835菌株的16 SrRNA序列与GenBank中的序列完全不同，与A38和D1菌株的16 SrRNA序列相似性较低，与Nor 37和39菌株的16 SrRNA序列相似性较高。
Butyrivibrio fibrisolvens strains D1 and A38 produced little lactate, but strain 49 converted as much as 75% of its glucose to lactate. Strain 49 had tenfold more lactate dehydrogenase activity than strains D1 or A38, this activity was stimulated by fructose 1,6-bisphosphate, and had a pH optimum of 6.25. A role for fructose 1,6-bisphosphate or pH regulation of lactate production in strain 39 was, however, contradicted by the observations that very low concentrations (< 0.2 mM) of fructose 1,6-bisphosphate gave maximal activity, and continuous cultures did not produce additional lactate when the pH was decreased. The lactate production of strain 49 was clearly inhibited by the presence of acetate in the growth medium. When strain 49 was supplemented with as little as 5 mM acetate, lactate production decreased dramatically, and most of the glucose was converted to butyrate. Strain 49 did not possess butyrate kinase activity, but it had a butyryl-CoA/acetate CoA transferase that converted butyryl-CoA directly to butyrate, using acetate as an acceptor. The transferase had a low affinity for acetate (K-m of 5 mM), and this characteristic explained the acetate stimulation of growth and butyrate formation. Strains D1 and A38 had butyrate kinase but not butyryl-CoA/acetate CoA transferase, and it appealed that this difference could explain the lack of acetate stimulation and lactate production. Based on these results, it is unlikely that B. fibrisolvens would ever contribute significantly to the pool of ruminal lactate. Since relatives of strain 49 (strains Nor37, PI-7, VV1, and OB156, based on 16S rRNA sequence analysis) all had the same method of butyrate production, it appeared that butyryl-CoA/acetate CoA transferase might be a phylogenetic characteristic. We obtained a culture of strain B835 (NCDO 2398) that produced large amounts of lactate and had butyryl-CoA/acetate CoA transferase activity, but this strain had previously been grouped with strains A38 and DI based on 16S rRNA sequence analysis. Our strain B835 had a 16S rRNA sequence unique from the one currently deposited in GenBank, and had high sequence similarity with strains 39 and Nor37 rather than with strains A38 or D1.