Department of Biochemistry, Tzu Chi University, Hualien, Taiwan, Republic of China.
PLoS One. 2011 May 12;6(5):e19982. doi: 10.1371/journal.pone.0019982.
Recent research shows that visible-light responsive photocatalysts have potential usage in antimicrobial applications. However, the dynamic changes in the damage to photocatalyzed bacteria remain unclear.
METHODOLOGY/PRINCIPAL FINDINGS: Facilitated by atomic force microscopy, this study analyzes the visible-light driven photocatalyst-mediated damage of Escherichia coli. Results show that antibacterial properties are associated with the appearance of hole-like structures on the bacteria surfaces. Unexpectedly, these hole-like structures were preferentially induced at the apical terminus of rod shaped E. coli cells. Differentiating the damages into various levels and analyzing the percentage of damage to the cells showed that photocatalysis was likely to elicit sequential damages in E. coli cells. The process began with changing the surface properties on bacterial cells, as indicated in surface roughness measurements using atomic force microscopy, and holes then formed at the apical terminus of the cells. The holes were then subsequently enlarged until the cells were totally transformed into a flattened shape. Parallel experiments indicated that photocatalysis-induced bacterial protein leakage is associated with the progression of hole-like damages, further suggesting pore formation. Control experiments using ultraviolet light responsive titanium-dioxide substrates also obtained similar observations, suggesting that this is a general phenomenon of E. coli in response to photocatalysis.
CONCLUSION/SIGNIFICANCE: The photocatalysis-mediated localization-preferential damage to E. coli cells reveals the weak points of the bacteria. This might facilitate the investigation of antibacterial mechanism of the photocatalysis.
最近的研究表明，可见光响应型光催化剂在抗菌应用中具有潜在的用途。然而，光催化细菌损伤的动态变化仍不清楚。
方法/主要发现：本研究借助原子力显微镜分析了可见光驱动的光催化剂介导的大肠杆菌损伤。结果表明，抗菌性能与细菌表面出现孔状结构有关。出乎意料的是，这些孔状结构优先出现在杆状大肠杆菌细胞的顶端。将损伤分为不同的等级，并分析细胞损伤的百分比，表明光催化可能会在大肠杆菌细胞中引发顺序损伤。该过程首先改变细菌细胞的表面特性，如原子力显微镜测量的表面粗糙度所示，然后在细胞的顶端形成孔。然后，这些孔会逐渐扩大，直到细胞完全变成扁平形状。平行实验表明，光催化诱导的细菌蛋白泄漏与孔状损伤的进展有关，进一步表明孔的形成。使用紫外线响应的二氧化钛基底的对照实验也得到了类似的观察结果，表明这是大肠杆菌对光催化的普遍反应。
结论/意义：光催化介导的大肠杆菌细胞定位优先损伤揭示了细菌的弱点。这可能有助于研究光催化的抗菌机制。
