New tolerant strains of purple nonsulfur bacteria for hydrogen production in a two-stage integrated system

In this study we described the isolation of eight new strains of purple non-sulfur bacteria resistant to salinity ≥30 g L−1 and high concentration of VFAs (200 mM). These strains were characterized by their general physiological properties and the occurrence of hupSL genes. Some correlation was observed between the rate of H2 photoproduction, the absence of hupSL genes and hydrogenase activity. Two fast-growing strains without hupSL genes showed high nitrogenase activity and hydrogen accumulation during growth on Ormerod medium. These strains were capable of H2 photoproduction using non-treated dark culture (75% in water) after dark fermentation of starch at 30 g L−1, unlike control strains, Rhodobacter capsulatus B10 and Rb. sphaeroides GL. New N7 and 13 strains identified as Rb. sphaeroides can be recommended for application in a two-stage H2 production system.

► New isolated strains of purple bacteria without HupSL hydrogenase.
► Correlation between the absence of hupSL genes and H2 photoproduction.
► Strains of purple bacteria resistant to salinity and VFA concentration.