Nitrate modulates microbial interaction and biocorrosion activities of acid producing bacteria

Acid-producing bacteria (APB) play significant role in pipeline corrosion by producing corrosive metabolites. Current APB mitigation strategies are often unsuccessful, costly, or not environmentally friendly. In this study, nitrate was used to manipulate microbial interaction and control APB activities. Microbial diversity was manipulated by subsampling and culturing sufficient replicates of serially diluted subsamples to achieve random distribution in the absence or presence of nitrate. Microbial activities were evaluated by monitoring changes in pH, corrosion rate, production of organic acids, changes in community composition, and functional gene abundance. The study identified a change in microbial community assemblage with decreased abundance of Clostridium upon nitrate addition, resulting in limited APB activities such as acid production and biocorrosion. Nitrate resulted in about a 3.5-fold decrease in carbon steel weight loss corrosion induced by APB but did not affect microbial growth and abundance of metabolic genes, suggesting that the inhibitory effect is likely due to changes in redox potential of culture media or increased growth of APB competitors. The study also identified the importance of nitrate as an economically viable and environmentally sustainable approach to mitigate APB-induced biocorrosion.