A study of electron transfer processes through biofilms in marine environments

摘要

Conductivity of biofilms can be considered to be beneficial for technical applications such as microbial fuel cells. On the other hand, conductive properties of living biofilms may have a strong impact on microbiologically influenced corrosion (MIC) mechanisms. To investigate the conductive properties of biofilms in marine environments, electrochemical impedance measurements (EIS) were performed under laboratory culture conditions. Experiments were conducted in modified artificial seawater with single or mixed bacterial strains: Pseudomonas fluorescence DSM 4358 and D.indonesiensis DSM 15121 from 1 up to 14 days of exposure. From step by step investigation of living and dead biofilms as well as purified exopolymeric substances (EPS) of the chosen bacterial strains, detailed information can be obtained about the possible electron transfer process within the biofilm. This study indicates that pure EPS compounds have a strong impact on conductive properties of biofilms. Parallel microscopy work by fluorescent staining and AFM imaging gave additional information regarding the topography of the biofilm. Furthermore, the conductivity of some species of marine bacterial biofilms could be proven. Further studies on the biological and physical properties of marine biofilms are necessary to fully understand this electron transfer process and its underlying mechanism.