Strobel H J
Department of Animal Sciences, University of Kentucky, Lexington 40517-0215.
FEMS Microbiol Lett. 1994 Oct 1;122(3):217-22. doi: 10.1111/j.1574-6968.1994.tb07170.x.
Butyrivibrio fibrisolvens is a fibrolytic ruminal bacterium that degrades hemicellulose and ferments the resulting pentose sugars. Washed cells of strain D1 accumulated radiolabelled xylose (Km = 1.5 microM) and arabinose (Km = 0.2 microM) when the organism was grown on xylose, arabinose, or glucose, but cultures grown on sucrose or cellobiose had little capacity to transport pentose. Glucose and xylose inhibited transport of each other non-competitively. Both sugars were utilized preferentially over arabinose, but since they did not inhibit transport of arabinose, it appeared that the preference was related to an internal metabolic step. Although the protonmotive force was completely abolished by ionophores, cells retained some ability to transport pentose. In contrast, the metabolic inhibitors iodoacetate, arsenate, and fluoride had little effect on protonmotive force but caused a large decrease in intracellular ATP and xylose and arabinose uptake. These results suggested that high-affinity, ATP-dependent mechanisms were responsible for pentose transport and hexose sugars affected the utilization of xylose and arabinose.
溶纤维丁酸弧菌是一种能降解半纤维素并发酵产生的戊糖的瘤胃纤维分解菌。当该菌在木糖、阿拉伯糖或葡萄糖上生长时，D1菌株的洗涤细胞积累了放射性标记的木糖（Km = 1.5微摩尔）和阿拉伯糖（Km = 0.2微摩尔），但在蔗糖或纤维二糖上生长的培养物运输戊糖的能力较弱。葡萄糖和木糖非竞争性地抑制彼此的运输。这两种糖都比阿拉伯糖更优先被利用，但由于它们不抑制阿拉伯糖的运输，似乎这种优先性与内部代谢步骤有关。尽管离子载体完全消除了质子动力，但细胞仍保留了一些运输戊糖的能力。相反，代谢抑制剂碘乙酸盐、砷酸盐和氟化物对质子动力影响很小，但导致细胞内ATP以及木糖和阿拉伯糖摄取量大幅下降。这些结果表明，高亲和力、依赖ATP的机制负责戊糖运输，己糖影响木糖和阿拉伯糖的利用。
