Long-term stable hydrogen production from acetate using immobilized Rhodobacter capsulatus in a panel photobioreactor

Abstract

Biological hydrogen production is attractive since renewable resources are utilized for hydrogen production. In this study, a novel panel photobioreactor (1.4 L) was constructed from Plexiglas with a network of nylon fabric support for agar immobilized bacteria complex. Two strains of Rhodobacter capsulatus DSM 1710 wild-type strain and Rhodobacter capsulatus YO3 (hup(-), uptake hydrogenase deleted mutant) with cell concentrations of 2.5 and 5.0 mg dcw/mL agar, respectively were entrapped by 4% (w/v) of agar. The system was operated for 72-82 days in a sequential batch mode utilizing acetate as substrate at 30 degrees C under continuous illumination. Immobilization increased the stability of the photobioreactors by reducing the fluctuations in pH. The pH remained between 6.7 and 8.0 during the process. Both hydrogen yield and productivity were higher in immobilized photobioreactors compared to suspended culture. The highest hydrogen productivities of 0.75 mmol H-2/L/h and 1.3 mmol H-2/L/h were obtained by R. capsulatus DSM1710 and R. capsulatus YO3 respectively. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.