Abstract
Escherichia coli utilizes by-product secretion in oxygen limiting conditions to recycle NADH and balance redox. NADH concentration and by-product secretions were qualitatively correlated with oxygen availability. NADH concentration was maintained in aerobic condition; however, increased as oxygen became limiting. GC analysis showed different by-product excretion patterns with varying oxygenation. Acetate was secreted equally under all conditions.