ABSTRACT
The gram-positive endospore-forming bacterium Bacillus subtilis has, under aerobic conditions, a branched respiratory system comprising one quinol oxidase branch and one cytochrome oxidase branch. The system terminates in one of four alternative terminal oxidases. Cytochrome caa
3 is a cytochromec oxidase, whereas cytochrome bd and cytochromeaa
3 are quinol oxidases. A fourth terminal oxidase, YthAB, is a putative quinol oxidase predicted from DNA sequence analysis. None of the terminal oxidases are, by themselves, essential for growth. However, one quinol oxidase (cytochromeaa
3 or cytochrome bd) is required for aerobic growth of B. subtilis strain 168. Data indicating that cytochrome aa
3 is the major oxidase used by exponentially growing cells in minimal and rich medium are presented. We show that one of the two heme-copper oxidases, cytochrome caa
3 or cytochromeaa
3, is required for efficient sporulation ofB. subtilis strain 168 and that deletion of YthAB in a strain lacking cytochrome aa
3 makes the strain sporulation deficient.
Cardiolipin enhances the enzymatic activity of cytochrome bd and cytochrome bo3 solubilized in dodecyl-maltoside
