Survival of bacteria during oxygen limitation

Regulatory mechanisms that enable bacteria associated with food, drinks and the human body to adapt to changes in the availability of oxygen are revie wed. Excess oxygen induces two adaptive responses to oxidative stress. Five or more control circuits enable enteric bacteria to generate energy and gr ow well in anaerobic environments. Two sets of enzymes catalyse both nitrat e and nitrite reduction, and dual two-component regulatory systems sense an d respond to the available nitrate and nitrite in the environment. The peri plasmic nitrate reductase enables bacteria to scavenge low concentrations o f nitrate: similar systems are found in food-borne and other pathogens. (C) 2000 Elsevier Science B.V. All rights reserved.