Influence Of Surface Wettability And Surface Charge On The Initial Adhesion Of Sulfate-reducing Bacteria And Vibrio Fischeri

Bifouling and microbiological induced corrosion (MIC) in marine environmenthave been two crucial issues we faced since we took up marine industries. The initialadhesion of microorganisms on materials is an important stage of bifouling and MIC.At the initial adhesion stage, the surface wettability and surface charge have significanteffects on adhesion amount and strength. In this thesis, a series of self-assembledmonolayers (SAMs) were fabricated to form surfaces with different wettability andcharge. The initial adhesion of two kinds of marine bacteria, Sulphate-reducingBacteria (SRB) and Vibrio fischeri, on different surfaces were investigated byelectrochemical impedance spectroscopy (EIS) and scanning electron microscopy(SEM). The main conclusions are as follows:(1) SAMs terminating with methyl, hydroxyl, amine and carboxyl can be used todesign and fabricate surfaces with different wettability and charge. EIS can reflectbacterial adhesion on materials by charge-transfer resistance (Rct) and its change rate(Rct%) with time. With SAMs and EIS, the study of bacterial adhesion can be moreefficient and convenient.(2) Influenced by interaction energy and electrostatic interactions, the adhesion ofSRB and Vibrio fischeri on more hydrophobic and more positively charged surface issuperior to the adhesion on more hydrophilic and more negatively charged surface. Inaddition, the adhesion of SRB which need strictly anaerobic conditions is superior tothe adhesion of Vibrio fischeri which are aerobic bacteria.(3) The surface wettability and surface charge can influence the adhesion of SRBand Vibrio fischeri only at the initial reversible stage which takes about3hours. Oncethe irreversible stage begins, the effect of surface wettability and surface chargediminish, and other factors like extract extracellular polymers play decisive rolesinstead.