Studies on relationships between flagellar motility and oxidative fermentation by acetic acid bacteria

乙酸细菌的氧化发酵，其中底物被呼吸链连接的脱氢酶氧化，将氧化产物积累到培养基中，例如来自乙醇的乙酸。这种不完全氧化产生质子动力穿过膜，用于驱动ATP合成等的能量。鞭毛是细菌的运动细胞器，它需要质子动力来工作。本研究假设，能量代谢是至关重要的氧化发酵。因此，调制醋酸菌的鞭毛运动性以观察对氧化发酵的影响。本研究通过反向遗传学方法发现（i）motB1基因参与鞭毛运动。(ii)乙酸细菌的鞭毛运动性由乙酸以及在生长后期的营养丰富的条件下诱导。(iii)使用不动突变体和高产突变体菌株进行的乙酸发酵研究表明，不动突变体生长优于野生型，但产酸水平与野生型几乎相同。这些数据表明，不动突变体的每个细胞的产酸能力比野生型差，因此运动性和氧化发酵之间呈正相关。

Oxidative fermentation by acetic acid bacteria, where substrates are oxidized by the respiratory chain-linked dehydrogenases, accumulates oxidation products to the culture medium, such as acetic acid from ethanol. Such incomplete oxidation produces proton motive force across the membrane for energy to drive ATP synthesis and others. Flagella are locomotive organelles of bacteria, which require proton motive force at work. This study hypothesizes that energy metabolism is crucial in the oxidative fermentation. Thus, the flagellar motility of acetic acid bacteria was modulated to see effects on the oxidative fermentation. This study found that (i) the motB1 gene is involved in the flagellar motility through reverse genetic approach. (ii) The flagellar motility of acetic acid bacteria is induced by acetic acid as well as under nutrient rich conditions in the late growth phase. (iii) Acetic acid fermentation study using immotile mutant and over producing mutant strains revealed that the immotile mutant grew better than wild type but produced acid at almost same levels of wild type. The data suggest that acid productivity per cell of the immotile mutant is worse than that of wild type, and thus positive correlation between motility and oxidative fermentation.