Bioelectrochemical Microfluidic Platform for Cultivation and Integrated Characterization of Exoelectrogenic Biofilms

Abstract

Microbial cultivation with the aid of microfluidic flow chambers has a great potential to form biofilms on an easy to handle laboratory scale. Our microfluidic cultivation platform with a modular design offers versatility and precision in terms of simulating different environments to study multiple growth conditions1. Thus, a long-term cultivation of biofilms can easily be obtained with the possibility of integrated on-line optical analysis. In this paper we will present our recent development of a bioelectrochemical microfluidic platform that allows cultivation and characterization of exoelectrogenic biofilms under anoxic conditions.Electroactive biofilms will be cultivated and characterized in the microfluidic bioelectrochemical system focusing on electroactive microorganisms such as Shewanella oneidensis. The conductive intracellular protein chain of these microbes enables extracellular electron transfer (EET) from the cytoplasm through the cell membranes to an insoluble electron acceptor, such as an anode 2. Different deletion strains were cultivated and could be examined and compared with each other by chronoamperometry, electrochemical impedance spectroscopy, cyclic voltammetry and confocal laser scanning microscopy (CLSM). Genetically engineered strains focus on probing key genes that affect the biofilm forming properties of Shewanella oneidensis 3. In-situ fluorescence microscopy studies of biofilm formation and interaction will also be presented based on our modular microfluidic bioelectrochemical platform. We will also present our ongoing research on artificial electroactive biofilms that integrate electrodeposited nanostructures with a biocompatible hydrogel to form an artificial biofilm matrix.In summary, electroactive biofilm growth under anoxic conditions using an anode as electron sink can be studied using our microfluidic flow technology. Examples of the versatility of the system as well as future outlooks on further biofilm growth conditions will be presented.