Nitrate Modulates Microbial Interaction and Biocorrosion Activities of Acid Producing Bacteria

Acid-producing bacteria (APB) play a significant role in pipeline corrosion by producing corrosive metabolites. Current APB mitigation strategies are often not successful, or the effects are temporary, necessitating the need to identify alternate approaches. In this study, nitrate was used to manipulate microbial interaction and control the growth and activities of APB. Microbial diversity was manipulated by subsampling a microbial consortia pool, serially diluting subsamples, and culturing sufficient replicates of each dilution to allow random distribution in the absence or presence of nitrate. The interactomes were grown in the presence of C1018 carbon steel, and corrosion activities were evaluated by monitoring the change in pH of the culture media, the corrosion of carbon steel, and the production of organic acids. Microbial community composition and functional gene abundance were also monitored. The study identified a change in microbial community assemblage upon nitrate addition, resulting in differences of APB activities, such as acid production, change of pH, and corrosion rate. Nitrate addition inhibited APB-induced corrosion but did not affect microbial growth and abundance of metabolic genes, suggesting that the inhibitory effect is likely due to change in redox potential of culture media or increased growth of APB competitors. The study also identified the importance of nitrate addition as a novel approach to manipulate microbial community composition and mitigate corrosion induced by APB activities. This approach is economically viable and an environmentally sustainable strategy to control microbiologically influenced corrosion.