Dynamics of microbial communities on the corrosion behavior of steel in freshwater environment

Abstract

In a freshwater environment, accelerated corrosion of carbon and stainless steels is frequently observed. Here, an immersion study was conducted using nine types of steels in a freshwater pool for 22 mo. Accelerated corrosion was observed in carbon and Cr-containing steels and cast iron, whereas no visible corrosion was observed in stainless steels, even after 22 mo. Microbial community analysis showed that, in general corrosion, Fe(II)-oxidizing bacteria were enriched in the early corrosion phase, Fe(III)-reducing bacteria increased in the corrosion-developing phase, and sulfate-reducing bacteria were enriched in the corrosion products during the final corrosion phase. In contrast, in the 9% Cr steel with localized corrosion, the family Beggiatocaea bacteria were particularly enriched. These microbial community compositions also differed from those in the water and sediment samples. Therefore, microbial communities are drastically altered with the progression of corrosion, and iron-dependent microbial energy metabolism contributes to an environment that enables the enrichment of other microorganisms.

Microbiologically influenced corrosion of stainless steel independent of sulfate-reducing bacteria

“…Higher Cr content in the S42000 steel and 15% Cr-stainless steel and Ni and Mo doping in the S41426 steel could have contributed to higher corrosion resistance compared with those of the S40300 stainless steel. Because our previous study showed corrosion in 9% Cr-steel immersed in freshwater ( Wakai et al, 2022 ), the Cr-content in the S42000 steel in the present study may be close to the threshold value for corrosion susceptibility in this environment. Although S40300 stainless steel generally does not corrode in freshwater environments, localized corrosion in check valve plugs made from S40300 stainless steel has been observed in actual facilities.…”

“…Amplicon sequencing was conducted to understand the differences in microbial communities in biofilms on metal surfaces over time. In 40 samples, 894,482 reads from S30400 and S31600 stainless steels (accession numbers: DRR334907–DRR334916; Wakai et al, 2022 ) and 2,774,371 reads, ranging from 40,565 to 128,474, from the rest were obtained. Thus, from a total of 3,668,853 reads, alpha and beta diversity and taxonomy plots were analyzed.…”

“…Industrial water is supplied by treating river water, and the quality was as follows: 10–30 ppm Cl − , 10–30 mS/m, 20–50 ppm Ca 2+ , 10–30 ppm SiO 2 , 1 ppm turbidity, pH 7.4, and ~ 8.2 ppm dissolved oxygen. As the pool did not have any temperature control system, the temperature varied ranging from 9 to 23°C.This arrangement is the same as that reported in Wakai et al (2022) . Two sets of ladders were withdrawn from the pool every 1, 3, 6, 14, and 22 months; the pieces from one of the ladders were used to determine the weight and corrosion rates and those from the remaining ladder were used for microbiome analysis.…”

“…Each sample withdrawn from the pool was transferred to a polyethylene bag and immediately frozen using dry ice pellets. DNA from the biofilm and corrosion products on the metal surface were extracted following the methods of Wakai et al (2022) . 1.8 ml of DNA/RNA shield solution (Zymo Research, Irvine, CA, United States) was poured into the bag, and the corrosion products and attached cells were recovered by washing the bag.…”

“…There are some studies on the MIC by sulfate-reducing bacteria (SRB; Ringas and Robinson, 1988 ; Webster and Newman, 1993 ; Antony et al, 2007 ; Xu et al, 2007 ; Li et al, 2009 ; Sun et al, 2011 ; Yuan et al, 2013 ; Liang et al, 2014 ; Zhang et al, 2015 ; Wu et al, 2019 , 2021 ). Moreover, we recently reported dynamic changes in microbial communities during the corrosion of some steels and the absence of SRB in the early corrosion phase ( Wakai et al, 2022 ), indicating that the detection and enrichment of SRB alone does not represent the corrosion process in the MIC.…”