Production of bio-fuels (hydrogen and lipids) through a photofermentation process

The purple non-sulfur photosynthetic bacteria Rhodopseudomonas palustris (strain 42OL) was investigated for a co-production of both bio-H2 and biodiesel (lipids). The investigation was carried out using malic and glutamic acids in a fed-batch cultivation system under continuous irradiances of 36, 56, 75, 151, 320, 500, and 803 W m-2. Boltzmann's sigmoidal regression model was used to determine growth kinetic parameters during hydrogen photoevolution. The upper limit of volumetric hydrogen photoevolution was 15.5 ± 0.9 ml l-1 h-1. During the entire cultivation period (408 h), the highest average hydrogen production rate (HPRav) of 11.1 ± 3.1 ml l-1 h-1 was achieved at an irradiance of 320 W m-2. Biomasses stored at the end of each experimental set were analyzed in order to determine lipid content, which ranged from a minimum of 22 ± 1% to a maximum of 39 ± 2% of biomass dry weight.