Application of immobilized Rhodobacter sphaeroides bacteria in hydrogen generation process under semi-continuous conditions

The non-modified and modified (AEAPTMS) VitraPOR®Filter porous glasses with thickness of 6.8 mm and diameter of 100 mm were applied as carriers for immobilization of Rhodobacter sphaeroides O.U. 001 bacteria. Two different glasses with pores of 40–100 and 100–160 μm were applied. The Van Nielʹs medium was applied for bacteria growth, whereas hydrogen generation reaction was performed with modified Biebl and Pfennig medium. Our own construction of Flat Plate Photobioreactor (FPP) with capacity of 200 cm3 operating under semi-continuous conditions was applied in this study. The maximum hydrogen production rate obtained was 0.059 dm3 H2/dm3/h, while the maximum hydrogen yield was 4.2 mol H2/mol malic acid. System was relatively stable because each series lasted about 3 months. Then the hydrogen production decreased. In order to introduce amine groups on the surface of porous glass, modification with AEAPTMS (3-(2-aminoethyl)aminopropyl)trimetoxysilane was performed. Obtained results proved that both modified and non-modified porous glasses are appropriate materials for stable immobilization of microbiological culture. The best activity and stability was achieved with porous glass matrix representing larger pores, whereas modification of the surface of these matrices with amine improved the amount of immobilized cells but did not improve the hydrogen yield.