Dejean L, Beauvoit B, Guérin B, Rigoulet M
Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Segalen, Bordeaux II, 1 rue Camille Saint Saëns, 33077, Bordeaux, France.
Biochim Biophys Acta. 2000 Feb 24;1457(1-2):45-56. doi: 10.1016/s0005-2728(00)00053-0.
The purpose of this study was to investigate the long-term control of ATP synthesis during the course of Saccharomyces cerevisiae batch grown on lactate, a purely respiratory substrate. For this, we used a respirometric and on-line calorimetric approach to analyse the energetic balances and the control of energetic metabolism during growth. Enthalpic growth yields assessed by enthalpy balance (taking account of substrate consumption, by-product accumulation, biomass formation and heat dissipation) remained constant during the entire exponential growth. Moreover, at the same time, a parallel decrease in basal respiratory rate and enthalpy flux occurred. It is shown that the decrease in respiration corresponds to a decrease in the amount of mitochondria per cell but not to a change of steady state of oxidative phosphorylation. Taking into account the part of energy used for maintenance, it can be concluded that mitochondria by themselves are the major heat dissipative system in a fully aerobic metabolism, and that the decrease in the amount of mitochondria when growth rate decreases leads to an enthalpic growth yield constant.
本研究的目的是调查酿酒酵母在乳酸（一种纯呼吸底物）分批培养过程中ATP合成的长期控制情况。为此，我们采用呼吸测定法和在线量热法来分析生长过程中的能量平衡和能量代谢控制。通过焓平衡评估的焓生长产率（考虑底物消耗、副产物积累、生物量形成和散热）在整个指数生长期保持恒定。此外，与此同时，基础呼吸速率和焓通量平行下降。结果表明，呼吸作用的下降对应于每个细胞中线粒体数量的减少，而不是氧化磷酸化稳态的变化。考虑到用于维持的能量部分，可以得出结论，线粒体本身是完全有氧代谢中的主要散热系统，并且当生长速率降低时线粒体数量的减少导致焓生长产率恒定。
