Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong 266237, China.
Department of Pharmacology, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250100, China.
Sci Total Environ. 2024 Aug 20;939:173613. doi: 10.1016/j.scitotenv.2024.173613. Epub 2024 May 28.
Riboflavin (RF), as a common electron mediator that can accelerate extracellular electron transfer (EET), is usually used as a probe to confirm EET-microbiologically influenced corrosion (MIC). However, the acceleration mechanism of RF on EET-MIC is still unclear, especially the effect on gene expression in bacteria. In this study, a 13-mer antimicrobial peptide E6 and tetrakis hydroxymethyl phosphonium sulfate (THPS) were used as new tools to investigate the acceleration mechanism of RF on Fe-to-microbe EET in corrosion of EH36 steel caused by Pseudomonas aeruginosa. 60 min after 20 ppm (v/v) THPS and 20 ppm THPS & 100 nM E6 were injected into P. aeruginosa 1 and P. aeruginosa 2 (two glass bottles containing P. aeruginosa with different treatments) at the 3-d incubation, respectively, P. aeruginosa 1 and P. aeruginosa 2 had a similar planktonic cell count, whereas the sessile cell count in P. aeruginosa 1 was 1.3 log higher than that in P. aeruginosa 2. After the 3-d pre-growth and subsequent 7-d incubation, the addition of 20 ppm (w/w) RF increased the weight loss and maximum pit depth of EH36 steel in P. aeruginosa 1 by 0.7 mg cm and 4.1 μm, respectively, while only increasing those in P. aeruginosa 2 by 0.4 mg cm and 1.7 μm, respectively. This suggests that RF can be utilized by P. aeruginosa biofilms since the corrosion rate should be elevated by the same value if it only acts on the planktonic cells. Furthermore, the EET capacity of P. aeruginosa biofilm was enhanced by RF because the protein expression of cytochrome c (Cyt c) gene in sessile cells was significantly increased in the presence of RF, which accelerated EET-MIC by P. aeruginosa against EH36 steel.
核黄素 (RF) 作为一种常见的电子介体，可以加速细胞外电子传递 (EET)，通常被用作确认微生物影响腐蚀 (MIC) 中电子传递的探针。然而，RF 对 EET-MIC 的加速机制尚不清楚，尤其是对细菌基因表达的影响。在本研究中，使用 13 肽抗菌肽 E6 和四羟甲基鏻硫酸盐 (THPS) 作为新工具，研究了 RF 对铜绿假单胞菌引起的 EH36 钢腐蚀中 Fe 到微生物 EET 的加速机制。在 3 天的孵育后，分别向含不同处理的铜绿假单胞菌的两个玻璃瓶（瓶 1 和瓶 2）中注入 20ppm（v/v）THPS 和 20ppm THPS+100nM E6，在 60 分钟后，瓶 1 和瓶 2 的浮游细胞计数相似，而瓶 1 的固着细胞计数比瓶 2 高 1.3 对数级。在 3 天的预生长和随后的 7 天孵育后，添加 20ppm（w/w）RF 分别使瓶 1 中 EH36 钢的失重和最大点蚀深度增加了 0.7mg cm 和 4.1μm，而仅使瓶 2 中 EH36 钢的失重和最大点蚀深度增加了 0.4mg cm 和 1.7μm。这表明 RF 可被铜绿假单胞菌生物膜利用，因为如果 RF 仅作用于浮游细胞，则腐蚀速率应该升高相同的值。此外，由于 RF 显著增加了固着细胞中细胞色素 c（Cyt c）基因的蛋白表达，增强了铜绿假单胞菌生物膜的 EET 能力，从而加速了铜绿假单胞菌对 EH36 钢的 MIC。
