HOW DO BACTERIA AVOID HIGH OXYGEN CONCENTRATIONS

Bacteria, such as Escherichia coli and Azospirillum brasilense, avoid microenvironments with elevated oxygen concentrations, not by sensing reactive oxygen derivatives, but by sensing a metabolic down-shift tha t results from elevated oxygen levels. A novel protein, Aer, and the c hemotaxis serine receptor, Tsr, have recently been identified as trans ducers for aerotaxis which monitor internal energy levels in the bacte ria.