Institutional Repository of Key Laboratory of Marine Environmental Corrosion and Bio-fouling, IOCAS
|Alternative Title||The diversity of microbial communities on the surface of matallic materials and their influenced corrosion mechanisms in marine environment|
|Place of Conferral||中国科学院海洋研究所|
|Keyword||海水腐蚀 油水环境 金属材料 微生物群落|
在实海中浸泡44个月的成熟铜合金生物膜中优势微生物为兼性厌氧菌如Woeseia sp.。环境压力调控基因rpoE和可能的重金属转运系统编码基因ABC.CD.P为优势基因，而铝合金和海水中的优势基因分别为DNA甲基转移酶和RNA合成酶编码基因。铜合金生物膜还含有丰富的耐铜基因cus，cop和 pco，以及EPS合成基因。而硫酸盐还原反应的关键基因dsr的丰度却极低，说明实海中铜合金的腐蚀并非全部由SRB及其产生的硫化物导致的。
原油极显著的促进了X70管线钢在海水中的腐蚀速率，对海泥中腐蚀速率影响不大。在海水中，原油主要通过促进微生物腐蚀来促进X70管线钢的腐蚀：在浸泡初期，APB为引发金属腐蚀的主要微生物；而浸泡后期，SRB尤其是Desulfovibrio和Desulfopila为引发金属腐蚀的主要微生物。添加原油使得海水的pH降低，并且硫酸根的消耗量变大；添加原油也促进海泥中硫酸根的消耗，但并不影响海泥的pH值。原油并没有促进海水中SRB的生长，但却促进了X70表面SRB生长。原油的添加使得海水中优势微生物由Spongiibacter转变成以石油烃类降解微生物如 Alcanivorax和Marinobacter为主的微生物群落结构，同样也使海泥中原有的优势微生物Pseudospirillum丰度降低，形成以APB Propionigenium为主的微生物群落结构。
Severe corrosion and biofouling problems of metallic materials suffered in marine environment have threatened the long-term security of important public infrastructures. Microbiologically inﬂuenced corrosion (MIC) is one of the causes of corrosion damage to metallic infrastructures in coastal seawater. In natural marine environments, various corrosion-causing microorganisms in a complicated biofilm act synergistically and contribute to more severe corrosion than single species is present. Thus, it is of great practical significance to study the composition of the microbial community on the metal surfaces and how they influence the corrosion mechanisms in natural marine environment. The composition and function diversity of attached microbial communities on metallic surfaces immersed in seawater, especially the communities formed on the surfaces of steel and copper alloys were studied using 16S rRNA gene sequencing and metagenomic sequencing as well as morphological and chemical analyses in present study. One of the common corrosive environments in coastal seawater, oil-seawater-sediment environment, was also simulated to study the features of corrosive microbial communities and their influenced MIC mechanisms using amplicon sequencing, most probable number (MPN) enumeration, combined with morphological and chemical analyses. The major results are as followed:
Compared to oligotrophic microbes in surrounding seawater, the dominant genus in the outer biofilm (without corrosion product) directly contacting with sweater was copiotrophic aerobic extracellular polymeric substances (EPS)-producing Pseudomonas. Additionally, sulfate-reducing bacteria (SRB) were detected in the rust layer, but the dominant genera changed from the outer layer to the inner part. The dominant genera detected in the outer, middle and inner rusts layers were Desulfotomaculum, Desulfonatronum (obligate anaerobe) and Desulfovibiro (electroactive), respectively. Further, diverse methanogens like Methanococcus and Methanothermococcus were also identified in the rust layer. The microorganisms in the outer rust layer of steel mainly used organic sulfides/polysulfides to synthesize sulfates and sulfites, which then entered the middle rust layer for dissimilated sulfates/ sulfites oxidation and reduction. The increase of hydrogen-cycling related genes including ech, coo and qmo from outer rust layer to inner layer suggested the increasing importance of hydrogen cycling from outside to inside rust layer.
Facultative anaerobic microbes such as Woeseia sp. were found to be the dominant groups on the copper surface immersed in coastal seawater for 44 months. Genes related to stress response and possible heavy metal transport systems, especially rpoE and ABC.CD.P were observed to be highly enriched in copper associated bioﬁlms, while genes encoding DNA-methyltransferase and RNA-polymerase subunit were highly enriched in aluminum-associated bioﬁlms and seawater planktonic cells, respectively. Moreover, copper-associated bioﬁlms harbored abundant copper resistance genes including cus, cop and pco, as well as abundant genes related to EPS production. The proportion of dsr in copper-associated bioﬁlms, key genes related to sulﬁde production, was as low as that in aluminum bioﬁlm and seawater, which ruled out the possibility of microbial sulﬁde-induced copper-corrosion under ﬁeld conditions.
It was found that crude oil significantly increased the corrosion rate of X70 pipeline steel in seawater, and did not significantly increase the corrosion rate in sea mud. Crude oil promoted the corrosion of X70 pipeline steel by stimulating MIC: In the early stage, APB was the main corrosion-causing bacteria; Afterwards, SRB, especially Desulfovibrio and Desulfopila, were responsible for the biocorrosion of X70. The addition of crude oil lowered the pH value of seawater and stimulated the sulfate consumption rate. Crude oil also promoted the rate of sulfate consumption in sea mud, but had no effect on the pH value of sea mud. Crude oil did not promote the growth of SRB in seawater, but it did promote the growth of SRB on the surface of X70. The dominant genera changed from Spongiibacter in seawater to hydrocarbon-degradating bacteria such as Alcanivorax and Marinobacter with crude oil. APB genus Propionigenium became the dominant bacteria in sea mud with crude oil, wheras Pseudospirillum dominated the microbial community in sea mud without crude oil.
|MOST Discipline Catalogue||理学|
|张一梦. 海洋环境金属表面微生物群落多样性及其腐蚀破坏机理[D]. 中国科学院海洋研究所. 中国科学院大学,2020.|
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