Evidence that available energy is a limiting factor in the bacterial corrosion of mild steel by a Pseudomonas sp.

Corrosion of mild steel coupons in cultures of Pseudomonas sp. no. 200 was inhibited (polarized) when the available energy was low, but was depolarized at high available substrate levels. Thus, the corrosion of the steel coupons which was partially inhibited in produced water was depolarized (made active) by the addition of 900 mg sodium lactate per litre. Also sustained corrosion of the steel coupons was only obtained at a high substrate level (1800 μg lactate∙L−1), and at lower levels (300 and 600 μg∙L−1) it was inhibited. Therefore, available energy is a limiting factor in bacterial corrosion of steel.