Abstract
In this study, we tested four algal species (Synechocystis sp. PCC 6803 and three novel algal species isolated from Egyptian paddy rice soil, having high 16S rRNA gene sequence identity to Nostoc spongiaeforme, Parachlorella kessleri SAG 211-11 and Nostoc sp. PCC 7524) under aerobic, anaerobic and 3% CO2-supplemented anaerobic condition. Significant changes in photohydrogen production, morphology, chlorophyll a and protein content/pattern were observed in all species, when grown in these different conditions. H-2 production was higher in anaerobic condition in all species with the highest H-2 production rate of 4 mmol H-2 mg Chla(-1) h(-1) at 24 h in Synechocystis sp. In contrast, Chla content and protein content decreased (%) in N. spongiaeforme, (29%, 58%), P. kessleri (47%, 7%) and Nostoc sp. (59%, 65%).The anaerobic condition with 3% CO2 stimulated early production of H-2 in all species except Synechocystis sp. Our results compared all selected algal species under different growth conditions for the screening of a superior H-2-producing algal species that can help to address engineering challenges in the field of large-scale H-2 photoproduction by microalgae. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.