Department of Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061.
Appl Environ Microbiol. 1983 Aug;46(2):321-7. doi: 10.1128/aem.46.2.321-327.1983.
Factors that may initiate the metabolic transition for butanol production were investigated in batch cultures of Clostridium beijerinckii (synonym, Clostridium butylicum) VPI 13436. Cultures maintained at pH 6.8 produced nearly as much butanol as those incubated without pH control, indicating that neither a change in the culture pH nor acid conditions per se are always required to initiate solvent formation. Acetate and butyrate levels at the onset of butanol production were dependent on the pH at which the cultures were maintained. Cultures maintained at pH 6.8 could be accelerated into solvent production by artificially lowering the pH to 5.0 or by the addition of acetate plus butyrate without a pH change (but neither acid alone was effective). Solvent production was associated with slower rates of growth and general metabolism, and it did not show a requirement for mature spore formation. We speculate that a slowdown in metabolism, which may be brought about by several conditions, is mechanistically related to the onset of butanol production. Extracts of solvent-producing cells contained acetoacetate decarboxylase activity as well as higher NADP-linked butanol dehydrogenase and lower hydrogenase activities than extracts of acid-producing cells. Solvent production did not appear to involve an enhanced ability to catalyze H(2) oxidation.
在分批培养中研究了可能引发丁酸生产代谢转变的因素。 Clostridium beijerinckii（同义词 Clostridium butylicum）VPI 13436 。在 pH 值为 6.8 的培养物中产生的丁酸与未进行 pH 值控制的培养物产生的丁酸几乎一样多，这表明培养物 pH 值的变化或酸条件本身并不总是需要启动溶剂形成。在开始生产丁酸时，乙酸盐和丁酸盐的水平取决于培养物保持的 pH 值。将 pH 值维持在 6.8 的培养物可以通过人为地将 pH 值降低到 5.0 或通过添加乙酸盐加丁酸盐而不改变 pH 值（但两者都没有单独有效）来加速进入溶剂生产。溶剂生产与生长和一般代谢的较慢速度有关，并且不需要成熟孢子的形成。我们推测，可能由几种条件引起的代谢减缓与丁酸生产的开始在机制上有关。与产酸细胞的提取物相比，产生溶剂的细胞的提取物中含有乙酰乙酸脱羧酶活性，以及更高的 NADP 连接的丁酸脱氢酶和更低的氢化酶活性。溶剂生产似乎不涉及增强的催化 H（2）氧化的能力。
