SURFACE PROPERTIES OF GALVANIZED METALS AND ATTACHMENT BY THE BACTERIUM JANTHINOBACTERIUM LIVIDUM

摘要

Atomic Force Microscopy (AFM) is a useful tool for characterizing material surface properties and studying in situ bacterial biofilms formed on metal surfaces. The aims of the present study were to evaluate metal surface roughness after a series of treatments and attachment of the bacterium Janthinobacterium lividum, isolated from a drinking-water catridge, and to establish the relationship between surface treatment and susceptibility to biofilm formation. The four metal coupons used included Al Galvanized 0.3 percent, 5 percent, 55 percent and a pure zinc plate. Our results showed that several roughness parameters including auto-covariance, Z-range, mean roughness and maximum height of the coupons increased with bacterial attachment on metal surfaces. There was a strong positive correlation between different roughness parameters and the number of bacteria attached on metal surfaces (r~2, 0.807 to 0.900) in an incubation experiment conducted for 7 days. Highest number of bacteria on surface was observed on coupons of Al Galvanized 55 percent, the roughest surface among the test coupons. The numbers of bacterial cells on coupon surfaces examined by Scanning Electron Microscopy (SEM) were 1.02 X10~5, 5.98 X10~4, 3.14 X10~4 and 1.07 X10~4/mm~2 for Al Galvanized 55 percent, 5 percent, 0.3 percent and pure zinc plate, respectively. Our data suggest that bacterial attachment on metal surfaces is strongly affected by surface morphological characteristics and modification of physical properties by surface treatment may decrease or increase the initial attachment by bacteria.