IOCAS-IR  > 海洋环境腐蚀与与生物污损重点实验室
海洋环境金属表面微生物群落多样性及其腐蚀破坏机理
Alternative TitleThe diversity of microbial communities on the surface of matallic materials and their influenced corrosion mechanisms in marine environment
张一梦
Subtype博士
Thesis Advisor段继周
2020-05-08
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学博士
Degree Discipline海洋腐蚀与防护
Keyword海水腐蚀 油水环境 金属材料 微生物群落
Abstract

金属材料在海洋环境中遭受的严重腐蚀与污损,是影响国家重要公共与基础设施安全长效运行的关键因素之一。微生物腐蚀是引发近海水下环境金属构筑物腐蚀破坏的重要原因。在实际海洋环境中,金属腐蚀并非只在单一物种的作用下发生,而是复杂的附着微生物群落共同作用的结果。因此研究实海环境中金属表面腐蚀微生物群落组成及其腐蚀破坏规律具有重要的实际意义。本文主要采用16S rRNA基因扩增子测序和宏基因组测序等技术,并结合表面分析等手段,对实海环境中的金属材料,尤其是钢铁材料和铜合金表面的附着微生物群落的组成和功能多样性进行研究,并在实验室模拟近海常见的腐蚀环境之一,采用扩增子测序、最大可能数计数法(MPN)、表面分析技术、理化因子测定等多种技术手段研究天然海水环境及有原油添加条件对海水和海泥中钢铁表面腐蚀微生物群落组成特点及其腐蚀破坏机理。主要结果有下:

与海水中寡营养型微生物相比,钢铁最外层与海水直接接触的生物膜(无腐蚀产物)中优势微生物为富营养型且可产生胞外多聚物(EPS)的Pseudomonas。碳钢不同深度锈层中的优势微生物都是硫酸盐还原菌(SRB),但按照需氧程度呈现出由外而内的优势菌属丰度差异:外锈层优势SRBDesulfotomaculum;中间锈层的优势SRB转变为严格厌氧的Desulfonatronum;最内层为具有电活性的Desulfovibiro。此外,在锈层中还发现了MethanococcusMethanothermococcus等多种产甲烷菌。钢铁材料外锈层微生物主要利用有机硫化物/多硫化物合成硫酸盐和亚硫酸盐,其次进入中间锈层用于异化型硫酸盐和亚硫酸盐的氧化和还原反应;氢循环基因数量如echcooqmo等从外锈层到中间锈层增多,意味着氢循环途径的重要性逐渐增加。

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cuscop 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DesulfovibrioDesulfopila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 AlcanivoraxMarinobacter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。

Other Abstract

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.

Subject Area生物学
MOST Discipline Catalogue理学
Language中文
Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/164684
Collection海洋环境腐蚀与与生物污损重点实验室
Recommended Citation
GB/T 7714
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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