Persistence of gluconeogenesis in Escherichia coli poisoned by oxidant stress.

The poisoning (inhibition of growth rate) of Escherichia coli by 4.2 atmospheres of hyperbaric oxygen was less when the culture energy source was glucose, fructose-6-phosphate, or glycerol, compared to pyruvate, oxaloacetate, or amino acids. This was consistent with previous indirect data which pointed to impaired gluconeogenesis in the toxicity mechanism. However, the three enzymes unique to gluconeogenesis (fructose-1, 6-diphosphatase, phosphoenolpyruvate synthase and phosphoenolpyruvate carboxyl-kinase) were not decreased in specific activity to a biologically significant extent in cell-free extract of cells poisoned by hyperbaric oxygen. Net glycogen synthesis in vivo was not decreased from glycerol, pyruvate or oxaloacetate, compared to glucose in cells exposed to oxidant stress from hyperbaric oxygen or 1 mM aerobic paraquat with cells exposed as exponentially growing cells prior to assay or as resting cells during the assay.