The energetic conversion competence of Escherichia coli during aerobic respiration studied by 31P NMR using a circulating fermentation system.

To determine the actual potential of the energetic conversion efficiency of Escherichia coli during aerobic respiration, apparent P/O ratios (P/O(app)) under either limited or standard glucose-feeding conditions were estimated. The previously reported circulating fermentation system (CFS) was used, and (31)P NMR saturation-transfer (ST) techniques were employed. By coupling with on-line NMR observations, CFS allowed us to evaluate cellular energetics directly, with both the dissolved oxygen tension and glucose feeding precisely controlled to prevent the effect of substrate-level phosphorylation based on aerobic or anaerobic acidogenesis in E.

In vivo NMR system for evaluating oxygen-dependent metabolic status in microbial culture.

To optimize an appropriate microbial culture in a fermentor, precise control of the medium's dissolved oxygen tension (DOT) is crucial. In particular, to study the effect of DOT on cellular metabolic status by using in vivo nuclear magnetic resonance (NMR) measurements, the set-up of the experiment must be optimized to maintain DOT in the culture. In the conventional method, DOT is monitored by a sensor inside a fermentor and is controlled by changing the agitation rate.