Collaborative or competitive interactions between bacteria and methanogens on the biocorrosion of Q235A steel

Bio-corrosion of Fe (0) metals in the actual environments results from the combined action of multiple microbes rather than the single action of one type of microbe. Nevertheless, the interspecies interactions between the corrosive microorganism and co-existing microbes, as well as their effects on the bio-corrosion of Fe (0) metals, remain unclear, especially for the interspecies interactions between methanogens and co-existed bacteria in microbiota in the absence of sulfate. Herein, the interspecies interactions between methanogens and co-existed bacteria in three different kinds of methanogenic microbiota (Methanothrix, Methanospirillum, or Methanobacterium dominant) and their effects on methanogens-influenced corrosion of Q235A steel were investigated. The initial results showed that competitive interactions existed between Methanothrix/Methanospirllum and fermentative acetogenic bacteria (Clostridiaceae_1, Family_XI, Peptostreptococcaceae, Pirllulaceae, and Tannerellaceae), while collaborative interactions existed between Methanobacterium and acetate-oxidizing bacteria (Synergistaceae and Spirochaetaceae). Further analysis demonstrated that the competitive interactions obstructed the attachment of Methanothrix/Methanospirllum and promoted the formation of dense corrosion products layer on the steel surface, thereby inhibiting Methanothrix/Methanospirllum-influenced corrosion. Contrarily, the collaborative interactions promoted the attachment of Methanobacterium and the formation of porous and loose corrosion products layer on the steel surface, thereby promoting Methanobacterium-influenced corrosion. Ultimately, the corrosion rate of steel induced by the Methanobacterium dominant microbiota (0.216 ± 0.042 mm/y) was much higher than by the Methanothrix/Methanospirllum dominant microbiota (0.009-0.046 mm/y). This work provided new insights into the understanding of the effects of co-existed bacteria on the corrosion of Fe (0) metals induced by methanogens in microbiota.