An Biwen Annie, Kleinbub Sherin, Ozcan Ozlem, Koerdt Andrea
Bundesanstalt für Materialforschung und -prüfung, Berlin, Germany.
Front Microbiol. 2020 Mar 31;11:527. doi: 10.3389/fmicb.2020.00527. eCollection 2020.
Currently, sulfate-reducing bacteria (SRB) is regarded as the main culprit of microbiologically influenced corrosion (MIC), mainly due to the low reported corrosion rates of other microorganisms. For example, the highest reported corrosion rate for methanogens is 0.065 mm/yr. However, by investigating methanogen-induced microbiologically influenced corrosion (Mi-MIC) using an in-house developed versatile multiport flow test column, extremely high corrosion rates were observed. We analyzed a large set of carbon steel beads, which were sectionally embedded into the test columns as substrates for iron-utilizing methanogen IM1. After 14 days of operation using glass beads as fillers for section separation, the highest average corrosion rate of IM1 was 0.2 mm/yr, which doubled that of IS5 and 16109 investigated at the same conditions. At the most corroded region, nearly 80% of the beads lost 1% of their initial weight (fast-corrosion), resulting in an average corrosion rate of 0.2 mm/yr for IM1-treated columns. When sand was used as filler material to mimic sediment conditions, average corrosion rates for IM1 increased to 0.3 mm/yr (maximum 0.52 mm/yr) with over 83% of the beads having corrosion rates above 0.3 mm/yr. Scanning electron images of metal coupons extracted from the column showed methanogenic cells were clustered close to the metal surface. IM1 is a hydrogenotrophic methanogen with higher affinity to metal than H. Unlike SRB, IM1 is not restricted to the availability of sulfate concentration in the environment. Thus, the use of the multiport flow column provided a new insight on the corrosion potential of methanogens, particularly in dynamic conditions, that offers new opportunities for monitoring and development of mitigation strategies. Overall, this study shows (1) under certain conditions methanogenic archaea can cause higher corrosion than SRB, (2) specific quantifications, i.e., maximum, average, and minimum corrosion rates can be determined, and (3) that spatial statistical evaluations of MIC can be carried out.
目前，硫酸盐还原菌（SRB）被认为是微生物影响腐蚀（MIC）的主要元凶，主要是因为其他微生物的腐蚀速率报告值较低。例如，产甲烷菌的最高报告腐蚀速率为0.065毫米/年。然而，通过使用自行开发的通用多端口流动测试柱研究产甲烷菌引起的微生物影响腐蚀（Mi-MIC），观察到了极高的腐蚀速率。我们分析了大量碳钢珠，这些碳钢珠被分段嵌入测试柱中，作为利用铁的产甲烷菌IM1的底物。在使用玻璃珠作为段间隔填充物运行14天后，IM1的最高平均腐蚀速率为0.2毫米/年，是在相同条件下研究的IS5和16109的两倍。在腐蚀最严重的区域，近80%的珠子损失了其初始重量的1%（快速腐蚀），导致IM1处理柱的平均腐蚀速率为0.2毫米/年。当使用沙子作为填充材料来模拟沉积物条件时，IM1的平均腐蚀速率增加到0.3毫米/年（最大值0.52毫米/年），超过83%的珠子腐蚀速率高于0.3毫米/年。从柱中提取的金属试片的扫描电子图像显示，产甲烷细胞聚集在金属表面附近。IM1是一种氢营养型产甲烷菌，与H相比，对金属具有更高的亲和力。与SRB不同，IM1不受环境中硫酸盐浓度可用性的限制。因此，多端口流动柱的使用为产甲烷菌的腐蚀潜力提供了新的见解，特别是在动态条件下，这为监测和制定缓解策略提供了新的机会。总体而言，本研究表明：（1）在某些条件下，产甲烷古菌可导致比SRB更高的腐蚀；（2）可以确定特定的量化指标，即最大、平均和最小腐蚀速率；（3）可以对MIC进行空间统计评估。
