Applications of Biofilm Reactors for Production of Value-Added Products by Microbial Fermentation

Abstract

© 2015 John Wiley & Sons, Ltd. All rights reserved. Biofilms represent a natural form of cell immobilization, and an increased concentration of biocatalyst (microorganisms) in the bioreactor when used to produce value-added products. The structure of the biofilm matrix provides resistance to extreme conditions of pH and temperature, contaminations, hydraulic shocks, antibiotics, and toxic substances. Biofilms reactors have been used to produce many value-added products, such as organic acids, alcohol, enzymes, antibiotics, bacteriocins, and more. Many bioreactor designs have been developed to favor the biofilm formation in the reactor, while allowing simultaneous planktonic growth to occur. They can be operated in batch, repeat batch or continuous mode, which can also affect the biofilm effectiveness. This bioreactor design generates microbial concentrations not possible in a conventional suspended-culture bioreactor. To stimulate biofilm development the support selection and design can be as simple as glass beads in a packed bed bioreactor to a complex as plastic composite supports (PCS) blend customized for the specific production microorganisms' physiology, produced as chips, rings, or tubes and operated in a packed bed, fluidized bed or PCS tubes attached to an agitator shaft bioreactor. Moreover, the support selection and design considerations include surface charge, hydrophobicity, porosity, roughness, particle diameter, and density. Some biofilm reactors limitations are difficulty in diffusion of oxygen and substrate into the biofilm and in the diffusion of product from the biofilm. This chapter will cover biofilm formation in different types of biofilm reactor designs, applications of biofilm reactors for productions of value-added products, and future trends.