Department of Biomedical and Chemical Engineering, Syracuse University , Syracuse, New York 13244, United States.
Syracuse Biomaterials Institute, Syracuse University , Syracuse, New York 13244, United States.
ACS Appl Mater Interfaces. 2017 Jul 12;9(27):22176-22184. doi: 10.1021/acsami.7b04757. Epub 2017 Jun 30.
Material stiffness has been shown to have potent effects on bacterial attachment and biofilm formation, but the mechanism is still unknown. In this study, response to material stiffness by Escherichia coli during attachment was investigated with biofilm assays and cell tracking using the Automated Contour-base Tracking for in Vitro Environments (ACTIVE) computational algorithm. By comparing the movement of E. coli cells attached on poly(dimethylsiloxane) (PDMS) surfaces of different Young's moduli (0.1 and 2.6 MPa, prepared by controlling the degree of cross-linking) using ACTIVE, attached cells on stiff surfaces were found more motile during early stage biofilm formation than those on soft surfaces. To investigate if motility is important to bacterial response to material stiffness, we compared E. coli RP437 and its isogenic mutants of flagellar motor (motB) and synthesis of flagella (fliC) and type I fimbriae (fimA) for attachment on 0.1 and 2.6 MPa PDMS surfaces. The motB mutant exhibited defects in response to PDMS stiffness (based on cell counting and tracking with ACTIVE), which was recovered by complementing the motB gene. Unlike motB results, mutants of fliC and fimA did not show significant defects on both face-up and face-down surfaces. Collectively, these findings suggest that E. coli cells can actively respond to material stiffness during biofilm formation, and motB is involved in this response.
材料硬度已被证明对细菌附着和生物膜形成有显著影响，但机制尚不清楚。本研究采用生物膜测定法和利用自动轮廓跟踪体外环境（ACTIVE）计算算法进行细胞跟踪，研究了大肠杆菌在附着过程中对材料硬度的反应。通过比较使用 ACTIVE 对不同杨氏模量（通过控制交联度制备的 0.1 和 2.6 MPa）的聚二甲基硅氧烷（PDMS）表面上附着的大肠杆菌细胞的运动，发现硬表面上的附着细胞在生物膜形成的早期阶段比软表面上的附着细胞更具运动性。为了研究运动性是否对细菌对材料硬度的反应很重要，我们比较了大肠杆菌 RP437 及其鞭毛马达（motB）和鞭毛合成（fliC）以及 I 型菌毛（fimA）的同源突变体在 0.1 和 2.6 MPa PDMS 表面上的附着情况。motB 突变体在响应 PDMS 硬度方面表现出缺陷（基于 ACTIVE 的细胞计数和跟踪），通过互补 motB 基因得到了恢复。与 motB 的结果不同，fliC 和 fimA 的突变体在正面和反面表面上均未显示出明显的缺陷。总之，这些发现表明，大肠杆菌细胞在生物膜形成过程中可以主动响应材料硬度，并且 motB 参与了这种反应。
