Sublethal THPS accelerates Pseudomonas-associated steel corrosion by stimulating biofilm development and microbial electron uptake

Biocides are widely employed to mitigate microbiologically influenced corrosion (MIC) in oil and gas fields. However, improper biocide dosing may result in changes to the MIC. This study investigated the corrosion behavior of the biofilm-forming Pseudomonas stutzeri on X70 pipeline steel under sublethal concentrations of tetrakis(hydroxymethyl) phosphonium sulfate (THPS) using cell counting, weight loss measurements, surface characterization, and transcriptomic analysis. The results revealed that THPS accelerated the corrosion of X70 steel in the presence of P. stutzeri, compared to THPS-free conditions. While THPS inhibited the growth of planktonic cells, it promoted biofilm formation on the X70 steel surface. Transcriptomic data suggested that this corrosion acceleration could be attributed to metabolic alterations in P. stutzeri, potentially enhancing electron transfer between bacterial cells and the steel surface. These findings provide guidance for the rational application of biocides in industrial settings.