The oil spill and the use of chemical surfactant reduce microbial corrosion on API 5L steel buried in saline soil

Biochemical and microbiological characterization of a thermotolerant bacterial consortium involved in the corrosion of Aluminum Alloy 7075

Microorganisms can play a significant role in material corrosion, with bacterial biofilms as major participants in microbially influenced corrosion (MIC). The exact mechanisms by which this takes place are poorly understood, resulting in a scarcity of information regarding MIC detection and prevention. In this work, a consortium of moderately thermophilic bacteria isolated from a biofilm growing over aluminum alloy 7075 was characterized. Its effect over the alloy was evaluated on a 40-day period using Electron Microscopy, demonstrating acceleration of corrosion in comparison to the abiotic control. The bacterial consortium was biochemically and microbiologically characterized as an attempt to elucidate factors contributing to corrosion. Molecular analysis revealed that the consortium consisted mainly of members of the Bacillus genus, with lower abundance of other genera such as Thermoanaerobacterium, Anoxybacillus and Paenibacillus. The EPS polysaccharide presented mainly mannose, galactose, rhamnose and ribose. Our observations suggest that the acidification of the culture media resulting from bacterial metabolism acted as the main contributor to corrosion, hinting at an unspecific mechanism. The consortium was not sulfate-reducing, but it was found to produce hydrogen, which could also be a compounding factor for corrosion.

Microbial community structure and shift pattern of industry brine after a long-term static storage in closed tank

Brine from Dingyuan Salt Mine (Anhui, China), an athalassohaline hypersaline environment formed in the early tertiary Oligocene, is used to produce table salt for hundreds of millions of people. However, halophiles preserved in this niche during deposition are still unknown. Here, we employed cultivation and high-throughput sequencing strategies to uncover the microbial community and its shift after a long-term storage in the brine collected from Dingyuan Salt Mine. High-throughput sequencing showed (1) in the fresh brine (2021), Cyanobium_stocktickerPCC-6307 spp. (8.46%), Aeromonas spp. (6.91%) and Pseudomonas spp. (4.71%) are the dominant species in bacteria while Natronomonas spp. (18.89%), Halapricum spp. (13.73%), and Halomicrobium spp. (12.35%) in archaea; (2) after a 3-year-storage, Salinibacter spp. (30.01%) and Alcanivorax spp. (14.96%) surpassed Cyanobium_stocktickerPCC-6307 spp. (8.46%) becoming the dominant species in bacteria; Natronomonas spp. are still the dominant species, while Halorientalis spp. (14.80%) outnumbered Halapricum spp. becoming the dominant species in archaea; (3) Alcanivorax spp. and Halorientalis spp. two hydrocarbons degrading microorganisms were enriched in the brine containing hydrocarbons. Cultivation using hypersaline nutrient medium (20% NaCl) combined with high-throughput 16S rRNA gene sequencing showed that (1) the biomass significantly increased while the species diversity sharply declined after a 3-year-storage; (2) Halorubrum spp. scarcely detected from the environment total stocktickerDNA were flourishing after cultivation using AS-168 or NOM medium; (3) twelve possible new species were revealed based on almost full-length 16S rRNA gene sequence similarity search. This study generally uncovered the microbial community and the dominant halophiles in this inland athalassohaline salt mine, and provided a new insight on the shift pattern of dominant halophiles during a long-term storage, which illustrated the shaping of microorganisms in the unique environment, and the adaptation of microbe to the specific environment.

Drying and rewetting induce changes in biofilm characteristics and the subsequent release of metal ions

Drying and rewetting can markedly influence the microbial structure and function of river biofilm communities and potentially result in the release of metal ions from biofilms containing metals. However, little information is available on the response of metal-enriched biofilms to drying and rewetting over time. In this study, natural biofilms were allowed to develop in four rotating annular bioreactors for 2-11 weeks, followed by drying for 5 days and rewetting for another 5 days. Subsequently, we assessed Zn, Cd, and As desorption from the biofilms and other related parameters (microbial community structure, biofilm morphology, enzyme activity, and surface components as well as characteristics). High-throughput sequencing of the 16 S rRNA gene and confocal laser scanning microscopy revealed that the biofilm architecture and bacterial communities were distinct in different growth phases and under drying and rewetting conditions (permutational multivariate analysis of variance; p = 0.001). Proteobacteria was the dominant bacterial phylum, accounting for 69.7-90.1% of the total content. Kinetic experiments revealed that the drying and rewetting process increased metal desorption from the biofilm matrix. The desorption of heavy metals was affected by the age of the biofilm, with the maximum amount of metal ions released from 2-week-old biofilms (one-way ANOVA, Zn: p < 0.001; Cd: p = 0.008; As: p < 0.001). The modifications in biofilm properties and decreased diversity of the bacterial community (paired t-test, p < 0.05) after drying and rewetting decreased the number of specific binding sites for metal ions. In addition, negatively charged arsenate and other anions in the liquid phase could compete with As ions for adsorption sites to promote the release of As(V) and/or reductive desorption of As(III). The results of this study and their interpretation are expected to help refine the behaviors of heavy metals in the aquatic environment.

Investigating the effects of environment, corrosion degree, and distribution of corrosive microbial communities on service-life of refined oil pipelines

Although the potential corrosive microbial communities of the refined oil pipelines can cause pipeline failure which directly threatens on soil and water environment, few studies have been published in this field. Therefore, the long-distance on-site internal corrosion detection and high-throughput sequencing techniques were employed in this study to investigate the distribution shifts of the corrosive microbial communities on the inner wall of a refined oil pipeline and its impact on the internal corrosion. The microorganisms colonizing on the inner wall of the pipeline showed significant distribution differences between the axial direction of the relative elevation and radial direction of the cross-section. On the inner wall, the high diversity and the abundance of the corrosive microbial communities induced serious microbiologically influenced corrosion (MIC), while the chemical corrosion and the synergy of the corrosive microbial communities accelerated the internal corrosion of the refined oil pipeline. A corrosion zone model has been proposed, which divides the pipeline cross-section into the sediment, the water-oil interface, the gas-oil interface, and the oil fully immersed zones. Therefore, the relationships between the environment, corrosion degree, and distribution characteristics of the corrosive microbial communities in the pipeline were analyzed. This research exhibited the importance of the distribution characteristics of the corrosive microorganisms on the inner wall of the refined oil pipelines. Its internal corrosion behavior was accurately explored, while providing a basis for controlling the corrosive microbial communities.

Electrochemical Corrosion Behaviour of X70 Steel under the Action of Capillary Water in Saline Soils

In this paper, the electrochemical corrosion behavior of X70 steel in saline soil under capillary water was simulated by a Geo-experts one-dimensional soil column instrument. A volumetric water content sensor and conductivity test were used to study the migration mechanism of water and salt (sodium chloride) under the capillary water. The electrochemical corrosion behavior of the X70 steel in the corrosion system was analyzed by electrochemical testing as well as the macroscopic and microscopic corrosion morphology of the steel. The test results showed that the corrosion behavior of X70 steel was significantly influenced by the rise of capillary water. In particular, the wetting front during the capillary water rise meant that the X70 steel was located at the three-phase solid/liquid/gas interface at a certain location, which worsened its corrosion behavior. In addition, after the capillary water was stabilized, the salts were transported with the capillary water to the top of the soil column. This resulted in the highest salt content in the soil environment and the most severe corrosion of the X70 steel at this location.

Microbially induced corrosion impacts on the oil industry

The numerous structural impacts on oil installations caused by corrosion make this issue a concern in the oil industry. Although chemical corrosion is relevant in this sector, it is indisputable that the microbial corrosion or bio-corrosion plays a preponderant role, with considerable economic losses. Microbial corrosion invariably depends on the formation of a biofilm on the attacked surface. Biofilm structures provide the conditions that favor the development of microbial groups related to corrosion. Despite the several microbial species are described as corrosive, certain groups, such as sulfate- and nitrate-reducing bacteria, acetogenic bacteria, and methanogenic archaea are the most commonly related. In spite of environmental factors influence the prevalence of certain species, it is increasingly accepted that the relationships between different species are determinant in corrosion. Such relationships can be evidenced by several surveys of microbial communities involved in bio-corrosion. Here, the main microbes related to corrosion in metallic structures used in oil installations are presented, as well as their metabolisms involved in the deterioration of metallic surfaces.

The impact of bacterial diversity on resistance to biocides in oilfields

Extreme conditions and the availability of determinate substrates in oil fields promote the growth of a specific microbiome. Sulfate-reducing bacteria (SRB) and acid-producing bacteria (APB) are usually found in these places and can harm important processes due to increases in corrosion rates, biofouling and reservoir biosouring. Biocides such as glutaraldehyde, dibromo-nitrilopropionamide (DBNPA), tetrakis (hydroxymethyl) phosphonium sulfate (THPS) and alkyl dimethyl benzyl ammonium chloride (ADBAC) are commonly used in oil fields to mitigate uncontrolled microbial growth. The aim of this work was to evaluate the differences among microbiome compositions and their resistance to standard biocides in four different Brazilian produced water samples, two from a Southeast Brazil offshore oil field and two from different Northeast Brazil onshore oil fields. Microbiome evaluations were carried out through 16S rRNA amplicon sequencing. To evaluate the biocidal resistance, the Minimum Inhibitory Concentration (MIC) of the standard biocides were analyzed using enriched consortia of SRB and APB from the produced water samples. The data showed important differences in terms of taxonomy but similar functional characterization, indicating the high diversity of the microbiomes. The APB and SRB consortia demonstrated varying resistance levels against the biocides. These results will help to customize biocidal treatments in oil fields.

Research status and development trends in the field of marine environment corrosion: a new perspective

Corrosion had aroused extensive concern and attention because it was an unavoidable problem for marine equipment and facilities in service. However, the current status and development trend of marine environment corrosion research had seldom been systematically studied. Therefore, it was encouraged to use bibliometrics and information visualization analysis methods to conduct bibliometric analysis of related publications in the field of marine environment corrosion based on HistCite, CiteSpace, and VOSviewer software programs. Compared with the traditional comments of researchers in this field, this research provided a direction for the development of quantitative analysis and visualization of marine environment corrosion on a large scale. The results showed that the overall focus of research in the field of marine environment corrosion continued to increase from 1900 to 2019. China had the highest publication productivity, the USA had the highest h-index value and the second highest average citations per item value, Materials Science was the most popular subject category, Corrosion Science was the main journal and Melchers RE was the author with the most output contributions. This research also exhibited four hot spots in this field. In addition, this work could help new researchers to find research directions and identify research trends and frontiers in the field of marine environment corrosion by tracing the research hotspots of topic categories, countries, institutions, journals, authors, and publications in recent years.

Influence of Salt Water Flow on Structures and Diversity of Biofilms Grown on 316L Stainless Steel

Salt water, in addition to being a naturally corrosive environment, also includes factors such as temperature, pressure, and the presence of the microbial community in the environment that influence degradation processes on metal surfaces. The presence or absence of water flow over the metal surfaces is also an important aspect that influences the corrosion of metals. The objective of this study was to evaluate the presence or absence of salt water flow in the formation of biofilms grown in 316L stainless steel coupons. For this, the 316L stainless steel coupons were exposed in two different microcosms, the first being a system with continuous salt water flow, and the second without salt water flow system. The results of the sequencing of the 16S rDNA genes showed a clear difference in structures and diversity between the evaluated biofilms. There was greater abundance and diversity in the "In Flux" system when compared to the "No Flux" biofilm. The analysis of bacterial diversity showed a predominance of the Gammaproteobacteria class in both systems. However, at lower taxonomic levels, there were considerable differences in representativeness. Representatives of Vibrionales, Alteromonadales, Oceanospirillales, and Flavobacteriales were predominant in "No Flux", whereas in "In Flux" there was a greater representation of Alteromonadales, Rhodobacterales, and Saprospirales. These findings help to understand how the flow of water influences the dynamics of the formation of microbial biofilms on metal surfaces, which will contribute to the choice of strategies used to mitigate microbial biofouling.