Kastner J R, Jones W J, Roberts R S
School of Biology, Georgia Institute of Technology, Atlanta 30332, USA.
Appl Microbiol Biotechnol. 1999 Jun;51(6):780-5. doi: 10.1007/s002530051462.
Candida shehatae cells, cultivated on D-glucose and D-xylose, were subjected to a shift from fully aerobic to anaerobic fermentative conditions. After anaerobic conditions were imposed, growth was limited to approximately one doubling or less as C. shehatae rapidly entered a stationary phase of growth. Following the shift to anoxia, cell viability rapidly declined and the total cell volume declined in the D-xylose fermentations. Moreover, the cell volume distribution shifted to smaller volumes. Cell viability, measured by plate counts, declined nine times faster for D-xylose fermentations than for D-glucose fermentations. Anaerobic growth did not occur on either D-glucose or D-xylose. Selected vitamins and amino acids did not stimulate anaerobic growth in C. shehatae, but did enhance anaerobic growth on D-glucose in S. cerevisiae. The decline in cell viability and lack of anaerobic growth by C. shehatae were attributed to oxygen deficiency and not to ethanol inhibition. The results shed light on why C. shehatae anaerobic fermentations are not currently practical and suggest that research directed towards a biochemical understanding of why C. shehatae can not grow anaerobically will yield significant improvements in ethanol fermentations from D-xylose.
在D-葡萄糖和D-木糖上培养的嗜杀假丝酵母细胞，从完全需氧条件转变为厌氧发酵条件。施加厌氧条件后，由于嗜杀假丝酵母迅速进入生长静止期，生长仅限于约一倍或更少的倍增。转变为缺氧状态后，在D-木糖发酵中细胞活力迅速下降，总细胞体积也下降。此外，细胞体积分布向较小体积转移。通过平板计数测量，D-木糖发酵中细胞活力下降速度比D-葡萄糖发酵快九倍。在D-葡萄糖或D-木糖上均未发生厌氧生长。选定的维生素和氨基酸不会刺激嗜杀假丝酵母的厌氧生长，但会增强酿酒酵母在D-葡萄糖上的厌氧生长。嗜杀假丝酵母细胞活力的下降和缺乏厌氧生长归因于缺氧而非乙醇抑制。这些结果揭示了为什么嗜杀假丝酵母厌氧发酵目前不实用，并表明针对从生化角度理解嗜杀假丝酵母为何不能厌氧生长的研究，将在D-木糖乙醇发酵中产生显著改进。
