Wang Yanan, Zhang Ruiyong, Mathivanan Krishnamurthy, Zhang Yimeng, Yang Luhua, Guan Fang, Duan Jizhou
Key Laboratory of Advanced Marine Materials, Key Laboratory of Marine Environmental Corrosion and Bio-Fouling, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Materials (Basel). 2024 Oct 17;17(20):5060. doi: 10.3390/ma17205060.
Microorganisms that exist in the seawater form microbial biofilms on materials used in marine construction, especially on metal surfaces submerged in seawater, where they form biofilms and cause severe corrosion. Biofilms are mainly composed of bacteria and their secreted polymeric substances. In order to understand how biofilms promote metal corrosion, planktonic and biofilm cells of SY-1 () from Q235 steel were collected and analyzed as to their intracellular proteome and extracellular polymeric substances (EPS). The intracellular proteome analysis showed that the cellular proteins were strongly regulated in biofilm cells compared to planktonic cells, e.g., along with flagellar proteins, signaling-related proteins were significantly increased, whereas energy production and conversion proteins and DNA replication proteins were significantly regulated. The up-and-down regulation of proteins revealed that biofilm formation by bacteria on metal surfaces is affected by flagellar and signaling proteins. A significant decrease in DNA replication proteins indicated that DNA is no longer replicated and transcribed in mature biofilms, thus reducing energy consumption. Quantitative analysis and lectin staining of the biofilm on the metal's surface revealed that the bacteria secreted a substantial amount of EPS when they began to attach to the surface, and proteins dominated the main components of EPS. Further, the infrared analysis showed that the secondary structure of the proteins in the EPS of the biofilm was mainly dominated by β-sheet and 3-turn helix, which may help to enhance the adhesion of EPS. The functional groups of EPS analyzed using XPS showed that the C element of EPS in the biofilm mainly existed in the form of combinations with N. Furthermore, the hydroxyl structure in the EPS extracted from the biofilm had a stronger hydrogen bonding effect, which could maintain the stability of the EPS structure and biofilm. The study results revealed that regulates the metabolic pathways and their secreted EPS structure to affect biofilm formation and cause metal corrosion, which has a certain reference significance for the study of the microbially influenced corrosion (MIC) mechanism.
海水中存在的微生物会在海洋工程所用材料上形成微生物生物膜，尤其是在浸没于海水中的金属表面，它们在这些表面形成生物膜并导致严重腐蚀。生物膜主要由细菌及其分泌的聚合物质组成。为了解生物膜如何促进金属腐蚀，收集了Q235钢表面SY-1（）的浮游细胞和生物膜细胞，并对其细胞内蛋白质组和胞外聚合物（EPS）进行分析。细胞内蛋白质组分析表明，与浮游细胞相比，生物膜细胞中的细胞蛋白质受到强烈调控，例如，与鞭毛蛋白一起，信号相关蛋白显著增加，而能量产生与转换蛋白以及DNA复制蛋白则受到显著调控。蛋白质的上调和下调表明，细菌在金属表面形成生物膜受到鞭毛蛋白和信号蛋白的影响。DNA复制蛋白的显著减少表明，DNA在成熟生物膜中不再复制和转录，从而降低了能量消耗。对金属表面生物膜的定量分析和凝集素染色表明，细菌开始附着于表面时会分泌大量EPS，且蛋白质占EPS的主要成分。此外，红外分析表明，生物膜EPS中蛋白质的二级结构主要以β-折叠和3-转角螺旋为主，这可能有助于增强EPS的附着力。使用XPS分析EPS的官能团表明，生物膜中EPS的C元素主要以与N结合的形式存在。此外，从生物膜中提取的EPS中的羟基结构具有更强的氢键作用，这可以维持EPS结构和生物膜的稳定性。研究结果表明， 调节代谢途径及其分泌的EPS结构以影响生物膜形成并导致金属腐蚀，这对微生物影响腐蚀（MIC）机制的研究具有一定的参考意义。
