Role of Cell Appendages in Initial Attachment and Stability of E. coli on Silica Monitored by Nondestructive TIRF Microscopy

Langmuir. 2017 Apr 25;33(16):4066-4075. doi: 10.1021/acs.langmuir.7b00314. Epub 2017 Apr 11.

Abstract

Total internal reflection fluorescence (TIRF) microscopy was used to investigate initial attachment and stability of wild-type, curli-deficient (ΔcsgA), flagella-deficient (ΔflhDC), and type-1 fimbriae-deficient (Δfim) mutant E. coli strains. Suspended bacteria were injected into a flow cell where they deposited on a silica coverslip, and images were acquired over a 2 min period. TIRF microscope image analysis revealed that curli- and flagella-deficient mutants attached closer to the surface and required a longer time to find their equilibrium position (i.e., bond maturation) as compared to the wild-type and fimbriae-deficient mutants. Analysis of the change in bacterial surface area over the 2 min period also indicated that curli- and flagella-deficient mutants have less initial stability than the wild-type and fimbriae-deficient mutants, evidenced by their fluctuating position at equilibrium. TIRF observations at the microscopic level were complemented macroscopically using quartz crystal microbalance with dissipation (QCM-D) and sand-packed column experiments, which support the distinctive behavior observed at the microscopic scale. For each mutant strain, as fluorescence intensity increased in TIRF, the negative frequency shift in QCM-D (related to the attached mass of bacteria) also increased. Packed-column experiments indicated that curli- and flagella-deficient mutants exhibited a characteristically different attachment behavior and more retention as compared to the wild-type and fimbriae-deficient strains. This study utilized a new approach to understand bacterial attachment/detachment and provides new insights into the role of various appendages on initial attachment and stability.

Publication types

  • Research Support, Non-U.S. Gov't