The energetics of bacterial growth: a reassessment.

The growth yield of microbial cultures can be used to estimate the efficiency of energy generation during a fermentation or respiration. In the past, the assessment of this efficiency in organisms carrying out a respiration has been the subject of many heated debates. This has partly been caused by the complexity of microbial respiratory chains. Strains of Escherichia coli specifically modified in their respiratory chain have been used recently to re-evaluate the energetic efficiency of the bacterial respiration using chemostat cultures. The different strains indeed show different growth efficiencies. The physiological significance of energetically less-efficient branches of the respiratory chain is discussed.