Microaerophilic bacteria transduce energy via oxidative metabolic gearing.

Heterotrophic microaerophilic bacteria, a diverse and ubiquitous group, are specialized for growth in O2 limited environments. Until recently, microaerophilic bacteria have been grouped with obligate aerobic organisms whose metabolic rates slow in response to physiological O2 limitation. In contrast, microaerophilic bacteria are adapted to maintain essentially constant turnover of primary energy substrates in response to a wide range of physiological O2. This capacity, oxidative metabolic gearing, allows microaerophilic bacteria to maintain catabolic enzymes, substrates, and cofactors at high steady-state levels. Oxidative metabolic gearing is thus adaptive, as it allows microaerophilic bacteria to respond to changes in physiological O2 relatively rapidly when compared to aerobic, anaerobic, or facultative microorganisms.