Departamento de Física Aplicada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP, Brazil.
J Colloid Interface Sci. 2011 Jul 1;359(1):289-95. doi: 10.1016/j.jcis.2011.03.066. Epub 2011 Mar 24.
Biofilms are complex microbial communities with important biological functions including enhanced resistance against external factors like antimicrobial agents. The formation of a biofilm is known to be strongly dependent on substrate properties including hydrophobicity/hydrophilicity, structure, and roughness. The adsorption of (macro)molecules on the substrate, also known as conditioning film, changes the physicochemical properties of the surface and affects the bacterial adhesion. In this study, we investigate the physicochemical changes caused by Periwinkle wilt (PW) culture medium conditioning film formation on different surfaces (glass and silicon) and their effect on X. fastidiosa biofilm formation. Contact angle measurements have shown that the film formation decreases the surface hydrophilicity degree of both glass and silicon after few hours. Atomic force microscopy (AFM) images show the glass surface roughness is drastically reduced with conditioning film formation. First-layer X. fastidiosa biofilm on glass was observed in the AFM liquid cell after a period of time similar to that determined for the hydrophilicity changes. In addition, attenuation total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy supports the AFM observation, since the PW absorption spectra increases with time showing a stronger contribution from the phosphate groups. Although hydrophobic and rough surfaces are commonly considered to increase bacteria cell attachment, our results suggest that these properties are not as important as the surface functional groups resulting from PW conditioning film formation for X. fastidiosa adhesion and biofilm development.
生物膜是具有重要生物学功能的复杂微生物群落，包括增强对外界因素（如抗菌剂）的抵抗力。生物膜的形成强烈依赖于底物特性，包括疏水性/亲水性、结构和粗糙度。（宏）分子在底物上的吸附，也称为调理膜，会改变表面的物理化学性质，并影响细菌的黏附。在这项研究中，我们研究了 PW 培养液调理膜在不同表面（玻璃和硅）上形成所引起的物理化学变化及其对 X. fastidiosa 生物膜形成的影响。接触角测量表明，在几小时后，薄膜形成会降低玻璃和硅的表面亲水性程度。原子力显微镜（AFM）图像显示，玻璃表面粗糙度在形成调理膜后大大降低。在 AFM 液体池中，一段时间后观察到玻璃上的第一层 X. fastidiosa 生物膜，这一时间与亲水性变化的确定时间相似。此外，衰减全反射傅里叶变换红外（ATR-FTIR）光谱支持 AFM 的观察，因为 PW 的吸收光谱随时间增加，磷酸盐基团的贡献更强。尽管疏水和粗糙的表面通常被认为会增加细菌细胞的附着，但我们的结果表明，对于 X. fastidiosa 的黏附和生物膜发育，这些特性不如 PW 调理膜形成所导致的表面官能团重要。
