Behavior of E. coli with Variable Surface Morphology Changes on Charged Semiconductor Interfaces

Bacterial behavior is often controlled by structural and composition elements of their cell wall. Using genetic mutant strains that change specific aspects of their surface structure, we modified bacterial behavior in response to semiconductor surfaces. We monitored the adhesion, membrane potential, and catalase activity of the Gram-negative bacterium Escherichia coli (E. coli) that were mutant for genes encoding components of their surface architecture, specifically flagella, fimbriae, curli, and components of the lipopolysaccharide membrane, while on gallium nitride (GaN) surfaces with different surface potentials. The bacteria and the semiconductor surface properties were recorded prior to the biofilm studies. The data from the materials and bioassays characterization supports the notion that alteration of the surface structure of the E. coli bacterium resulted in changes to bacterium behavior on the GaN medium. Loss of specific surface structure on the E. coli bacterium reduced its sensitivity to the semiconductor interfaces, while other mutations increase bacterial adhesion when compared to the wild-type control E. coli bacteria. These results demonstrate that bacterial behavior and responses to GaN semiconductor materials can be controlled genetically and can be utilized to tune the fate of living bacteria on GaN surfaces.

细菌的行为通常受其细胞壁的结构和组成成分所控制。利用改变其表面结构特定方面的基因突变菌株，我们改变了细菌对半导体表面的反应行为。我们监测了革兰氏阴性菌大肠杆菌（E. coli）的黏附、膜电位和过氧化氢酶活性，这些大肠杆菌的表面结构成分（特别是鞭毛、菌毛、卷曲菌毛以及脂多糖膜的成分）编码基因发生了突变，同时将它们置于具有不同表面电位的氮化镓（GaN）表面上。在生物膜研究之前，对细菌和半导体表面特性进行了记录。来自材料和生物测定表征的数据支持这样一种观点，即大肠杆菌表面结构的改变导致其在GaN介质上的行为发生变化。大肠杆菌特定表面结构的缺失降低了其对半导体界面的敏感性，而与野生型对照大肠杆菌相比，其他突变则增加了细菌的黏附性。这些结果表明，细菌的行为以及对GaN半导体材料的反应可以通过基因进行控制，并可用于调节活细菌在GaN表面上的命运。