Absence of Diauxie during Simultaneous Utilization of Glucose and Xylose by Sulfolobus acidocaldarius
Absence of Diauxie during Simultaneous Utilization of Glucose and Xylose by Sulfolobus acidocaldarius
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DOI：
10.1128/jb.01219-10
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发表时间：
2011-03-01
影响因子：
3.2
通讯作者：
Keasling, Jay D.
中科院分区：
文献类型：
--
作者：
Joshua, Chijioke J.;Dahl, Robert;Keasling, Jay D.
酸热硫化叶菌利用葡萄糖和木糖作为唯一碳源，但其同时代谢这些糖的能力尚不清楚。我们报道了在S.酸热菌对葡萄糖和木糖作为共碳源的依赖性。葡萄糖的存在并不抑制木糖的利用。该微生物同时利用每升1克的每种糖的混合物，比生长速率为0.079 h（-1），并且对利用每种糖的顺序没有偏好。以2克/升木糖为唯一碳源时，该菌生长速度（0.074 h（-1））比等量葡萄糖（0.022 h（-1））快。当在两种碳源的混合物上生长时，随着木糖与葡萄糖的比例从0.25增加到4，生物体的生长速率从0.052 h（-1）增加到0.085 h（-1）。S.嗜酸热菌似乎以与培养基中葡萄糖和木糖的浓度大致成比例的速率利用葡萄糖和木糖的混合物，导致几乎同时完全利用两种糖。在单独的木糖上生长的细胞中的基因表达与在木糖和葡萄糖的混合物上生长的细胞中的基因表达非常相似，并且与在单独的葡萄糖上生长的细胞中的基因表达显著不同。该生物体利用糖混合物的机制尚未阐明。
Sulfolobus acidocaldarius utilizes glucose and xylose as sole carbon sources, but its ability to metabolize these sugars simultaneously is not known. We report the absence of diauxie during growth of S. acidocaldarius on glucose and xylose as co-carbon sources. The presence of glucose did not repress xylose utilization. The organism utilized a mixture of 1 g/liter of each sugar simultaneously with a specific growth rate of 0.079 h(-1) and showed no preference for the order in which it utilized each sugar. The organism grew faster on 2 g/liter xylose (0.074 h(-1)) as the sole carbon source than on an equal amount of glucose (0.022 h(-1)). When grown on a mixture of the two carbon sources, the growth rate of the organism increased from 0.052 h(-1) to 0.085 h(-1) as the ratio of xylose to glucose increased from 0.25 to 4. S. acidocaldarius appeared to utilize a mixture of glucose and xylose at a rate roughly proportional to their concentrations in the medium, resulting in complete utilization of both sugars at about the same time. Gene expression in cells grown on xylose alone was very similar to that in cells grown on a mixture of xylose and glucose and substantially different from that in cells grown on glucose alone. The mechanism by which the organism utilized a mixture of sugars has yet to be elucidated.