Hydrogen and polyhidroxybutyrate (phb) production by a photoheterotrophic mixed culture

Biological Hydrogen (H2) production has been mainly developed via Anaerobic Digestion (AD). Most of the studies demonstrate that the main drawback of this process is the low H2 yields due to the generation of some organic acids as by-products. Those can be used as feedstock for other processes. Phototrophic bacteria from the Rhodobacter and Rhodopseudomonas genus have been identified as potential H2 producers since they have the metabolic machinery for its production when growing on organic acids. However, H2 is produced by a complex enzymatic system which is not yet fully understood. Additionally, the use of mixed phototrophic cultures for the H2 production has the potential to increase the yield when the final products of AD are used as substrate. The aim of this project was to evaluate H2 and PHB production by mixed phototrophic cultures when feeding with organic acids.