Hydrogen Production by Suspension and Immobilized Cultures of Phototrophic Microorganisms. Technological Aspects

Abstract

Photobiological production of hydrogen (H2) is one of the methods of H2 production. However, the immediate application of phototrophic bacteria in biotechnological systems of H2 generation is not possible because of several reasons, such as low efficiency of light energy bioconversion and low specific rates of hydrogen photoproduction. This chapter discusses the possible impact of technological methods such as continuous medium flow, photobioreactor with particular illumination design, and immobilized cells on the solution of such problems in the case of nitrogenase-driven H2 production. Continuous cultures have continuous medium input and culture output and are ideal for investigations of the culture response to changes of particular cultivation factor. The chapter lists a table containing the maximum H2 photoproduction by continuous cultures of purple bacteria. The photobioreactor construction provides uniform light intensity to the culture. Immobilized cells are widely used for both practical and academic purposes. The methods for immobilizing whole cells include entrapment by an inert support like gel, adsorption by an inert support like ion exchange material, binding via immobilized biological macromolecules or attachment to the activated surface of the matrix, and autoimmobilization. Application of immobilization technique and designing of matrix with thin layer allow high cell density to be reached in one unit of volume.