Jayaraman A, Sun A K, Wood T K
Department of Chemical and Biochemical Engineering & Materials Science, University of California, Irvine 92697-2575, USA.
J Appl Microbiol. 1998 Apr;84(4):485-92. doi: 10.1046/j.1365-2672.1998.00359.x.
Corrosion inhibition of SAE 1018 steel by Pseudomonas fragi and Escherichia coli biofilms has been evaluated using batch cultures in rich medium (LB) and seawater-mimicking medium (VNSS) at 23 degrees C and 30 degrees C with or without daily medium replenishment. Biofilm components have been stained simultaneously for polysaccharide (calcofluor) and live and dead cells (Live/Dead Baclit viability kit) and visualized using confocal scanning laser microscopy (CSLM). Image analysis was used to quantify the relative proportions of live cells, dead cells, polysaccharide and void space in the biofilm. This staining technique and examination of the architecture of biofilms responsible for inhibiting metal corrosion revealed that both Ps. fragi and E. coli produce polysaccharide only in the seawater medium; in rich medium, the biofilm consisted mainly of a layer of sessile cells near the biofilm-metal interface and sparse thick clumps of cells at the biofilm-liquid interface. Biofilms of both strains had a higher proportion of live cells in the rich medium than in the seawater-mimicking medium at the higher temperature, and more live cells were present at the higher temperature for LB medium. The corrosion inhibition observed (2.3-6.9-fold in 8 d) was not significantly affected by medium type or replenishment. Increase in the cellular content of the biofilms, as a result of increasing temperature, led to a reduction in corrosion.
在23摄氏度和30摄氏度下，使用富含培养基（LB）和模拟海水培养基（VNSS）的分批培养法，评估了脆弱拟杆菌和大肠杆菌生物膜对SAE 1018钢的缓蚀作用，培养过程中有或没有每日更换培养基。同时对生物膜成分进行多糖（钙荧光白）以及活细胞和死细胞（Live/Dead Baclit活力试剂盒）染色，并使用共聚焦扫描激光显微镜（CSLM）进行观察。图像分析用于量化生物膜中活细胞、死细胞、多糖和空隙空间的相对比例。这种染色技术以及对抑制金属腐蚀的生物膜结构的检查表明，脆弱拟杆菌和大肠杆菌仅在海水培养基中产生多糖；在富含培养基中，生物膜主要由靠近生物膜-金属界面的一层固着细胞和生物膜-液体界面处稀疏的厚细胞团组成。在较高温度下，两种菌株的生物膜在富含培养基中的活细胞比例高于模拟海水培养基，并且在LB培养基中较高温度下存在更多活细胞。观察到的缓蚀作用（8天内为2.3至6.9倍）不受培养基类型或更换的显著影响。由于温度升高导致生物膜细胞含量增加，从而使腐蚀减少。
