Biodiversity analysis by polyphasic study of marine bacteria associated with biocorrosion phenomena

Aims: A polyphasic approach was used to study the biodiversity bacteria associated with biocorrosion processes, in particular sulfate‐reducing bacteria (SRB) and thiosulfate‐reducing bacteria (TRB) which are described to be particularly aggressive towards metallic materials, notably via hydrogen sulfide release. Methods and Results: To study this particular flora, an infrared spectra library of 22 SRB and TRB collection strains were created using a Common Minimum Medium (CMM) developed during this study and standardized culture conditions. The CMM proved its ability to allow for growth of both SRB and TRB strains. These sulfurogen collection strains were clearly discriminated and differentiated at the genus level by fourier transform infrared (FT‐IR) spectroscopy. In a second step, infrared spectra of isolates, recovered from biofilms formed on carbon steel coupons immersed for 1 year in three different French harbour areas, were compared to the infrared reference spectra library. In parallel, molecular methods (M13‐PCR and 16S rRNA gene sequencing) were used to qualitatively evaluate the intra‐ and inter‐species genetic diversity of biofilm isolates. The biodiversity study indicated that strains belonging to the Vibrio genus were the dominant population; strains belonging to the Desulfovibrio genus (SRB) and Peptostreptococcaceae were also identified. Conclusion: Overall, the combination of the FT‐IR spectroscopy and molecular approaches allowed for the taxonomic and ecological study of a bacterial flora, cultivated on CMM, associated with microbiology‐induced corrosion (MIC) processes. Significance and Impact of the Study: Via the use of the CMM medium, the culture of marine bacteria (including both SRB and TRB bacteria) was allowed, and the implication of nonsulforogen bacteria in MIC was observed. Their involvement in the biocorrosion phenomena will have to be studied and taken into account in the future.     

The role of iron-oxidizing bacteria in biocorrosion: a review

Abstract

Lithotrophic iron-oxidizing bacteria depend on reduced iron, Fe(II), as their primary energy source, making them natural candidates for growing in association with steel infrastructure and potentially contributing to microbially influenced corrosion (MIC). This review summarizes recent work on the role of iron-oxidizing bacteria (FeOB) in MIC. By virtue of producing complex 3-dimensional biofilms that result from the accumulation of iron-oxides, FeOB may aid in the colonization of steel surfaces by other microbes involved in MIC. Evidence points to a successional pattern occurring whereby FeOB are early colonizers of mild steel (MS), followed by sulfate-reducing bacteria and other microbes, although studies of aged corrosion products indicate that FeOB do establish a long-term presence. There is evidence that only specific clades of FeOB, with unique adaptations for growing on steel surfaces are part of the MIC community. These are discussed in the context of the larger MIC microbiome.     

The influence of iron content on the biofouling resistance of 90/10 copper‐nickel alloys

A series of 90/10 cupronickel alloys containing iron at levels between 0% and 5% were immersed in the sea in Chichester Harbour. Samples were retrieved over a 14‐month period and subjected to scanning electron microscopy, energy dispersive X‐ray analysis and X‐ray photoelectron spectroscopy. The alloy with no iron corroded very rapidly and showed little, if any, colonisation. The 0·5% Fe and 1·5% Fe alloys developed microfouling communities dominated by the diatom Amphora, while the 2·5% and 5% Fe‐containing materials showed not only diatoms but also macro‐fouling in the form of barnacle settlement. However, the very loosely adherent nature of the iron and nickel‐rich corrosion products of these high iron alloys resulted in very poor tenacity of adhesion by the macrofouling. However, thick films of diatoms of lower copper tolerance became well established on the iron‐rich alloys. The alternative anti‐fouling mechanisms of the 90/10 copper‐nickels are discussed.     

Sulphide production and corrosion in seawaters during exposure to FAME diesel

Experiments were designed to evaluate the corrosion-related consequences of storing/transporting fatty acid methyl ester (FAME) alternative diesel fuel in contact with natural seawater. Coastal Key West, FL (KW), and Persian Gulf (PG) seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used in 60 day incubations with unprotected carbon steel. The original microflora of the two seawaters were similar with respect to major taxonomic groups but with markedly different species. After exposure to FAME diesel, the microflora of the waters changed substantially, with Clostridiales (Firmicutes) becoming dominant in both. Despite low numbers of sulphate-reducing bacteria in the original waters and after FAME diesel exposure, sulphide levels and corrosion increased markedly due to microbial sulphide production. Corrosion morphology was in the form of isolated pits surrounded by an intact, passive surface with the deepest pits associated with the fuel/seawater interface in the KW exposure. In the presence of FAME diesel, the highest corrosion rates measured by linear polarization occurred in the KW exposure correlating with significantly higher concentrations of sulphur and chlorine (presumed sulphide and chloride, respectively) in the corrosion products.     

Influence of an oil soluble inhibitor on microbiologically influenced corrosion in a diesel transporting pipeline

Abstract

Microbial degradation of the oil soluble corrosion inhibitor (OSCI) Baker NC 351 contributed to a decrease in inhibitor efficiency. Corrosion inhibition efficiency was studied by the rotating cage and flow loop methods. The nature of the biodegradation of the corrosion inhibitor was also analysed using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. The influence of bacterial activity on the degradation of the corrosion inhibitor and its influence on corrosion of API 5LX were evaluated using a weight loss technique and impedance studies. Serratia marcescens ACE2 and Bacillus cereus ACE4 can degrade aromatic and aliphatic hydrocarbons present in the corrosion inhibitor. The present study also discusses the demerits of the oil soluble corrosion inhibitors used in petroleum product pipeline.     

Role of sulfate‐reducing bacteria in corrosion of mild steel: A review

The influence of sulfate‐reducing bacteria on corrosion of mild steel is reviewed, with special emphasis on the effects of biofilm structure and function, medium composition (dissolved oxygen and ferrous ion concentrations) and the physical and chemical properties of iron sulfides. A summary of different corrosion mechanisms is critically discussed, based on electrochemical and rate process analyses. A mechanism is proposed which explains the high corrosion rates observed in the field.     

60Coγ射线引发聚合的丙烯酸共聚物阻垢缓蚀剂性能研究

采用60Coγ射线引发聚合制备了丙烯酸共聚物阻垢缓蚀剂,考察了该阻垢缓蚀剂与国内同类产品在不同环境条件下的阻垢率和缓蚀率,实验表明：该阻垢缓蚀剂具有耐高温,耐碱的优点,阻垢和缓蚀性能优于国内同类产品;经过半年的工业现场应用试验,取得了很好的效果.     

Diverse bacterial groups are associated with corrosive lesions at a Granite Mountain Record Vault (GMRV)

Aims: This study applied culture‐dependent and molecular approaches to examine the bacterial communities at corrosion sites at Granite Mountain Record Vault (GMRV) in Utah, USA, with the goal of understanding the role of microbes in these unexpected corrosion events. Methods and Results: Samples from corroded steel chunks, rock particles and waters around the corrosion pits were collected for bacterial isolation and molecular analyses. Bacteria cultivated from these sites were identified as members of Alphaproteobacteria, Gammaproteobacteria, Firmicutes and Actinobacteria. In addition, molecular genetic characterization of the communities via nested‐polymerase chain reaction‐denaturing gradient gel electrophoresis (DGGE) indicated the presence of a broad spectrum of bacterial groups, including Alphaproteobacteria, Betaproteobacteria, Deltaproteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. However, neither cultivation nor molecular approaches identified sulfate‐reducing bacteria (SRB), the bacteria commonly implicated as causative organisms were found associated with corrosive lesions in a process referred to as microbially influenced corrosion (MIC). The high diversity of bacterial groups at the corrosion sites in comparison with that seen in the source waters suggested to us a role for the microbes in corrosion, perhaps being an expression of a redox‐active group of microbes transferring electrons, harvesting energy and producing biomass. Conclusions: The corrosion sites contained highly diverse microbial communities, consistent with the involvement of microbial activities along the redox gradient at corrosion interface. We hypothesize an electron transport model for MIC, involving diverse bacterial groups such as acid‐producing bacteria (APB), SRB, sulfur‐oxidizing bacteria (SOB), metal‐reducing bacteria (MRB) and metal‐oxidizing bacteria (MOB). Significance and Impact of the Study: The characterization of micro‐organisms that influence metal‐concrete corrosion at GMRV has significant implications for corrosion control in high‐altitude freshwater environments. MIC provides a potential opportunity to further our understandings of extracellular electron transfer and interspecies communications.