Microbial growth quantified here as inverse doubling times represent a more holistic measure of adaptation in vivo because Acidovorax sp. strain JS42 utilizes nitroaromatic substrates as the sole source of carbon and energy. Activity of the dioxygenase and its efficiency to oxygenate the substrate are thus expected to be reflected in microbial growth rates. In fact, . No growth was assigned a value of 0 h -1 .