Simazine Enhances Dark Fermentative H2 Production by Unicellular Halotolerant Cyanobacterium Aphanothece halophytica

The halotolerant cyanobacterium Aphanothece halophytica is a potential H-2 producer that induces H-2 evolution under nitrogen deprivation. H-2 is mainly produced via the catabolism of stored glycogen under dark anaerobic condition. H-2 evolution is catalyzed by O-2-sensitive bidirectional hydrogenase. The aim of this study was to improve H-2 production by A. halophytica using various kinds of inhibitors. Among all types of inhibitors, simazine efficiently promoted the highest H-2 production under dark conditions. High simazine concentration and long-term incubation resulted in a decrease in cell and chlorophyll concentrations. The optimal simazine concentration for H-2 production by A. halophytica was 25 mu M. Simazine inhibited photosynthetic O-2 evolution but promoted dark respiration, resulting in a decrease in O-2 level. Hence, the bidirectional hydrogenase activity and H-2 production was increased. A. halophytica showed the highest H-2 production rate at 58.88 +/- 0.22 mu mol H-2 g(-1) dry weight h(-1) and H-2 accumulation at 356.21 +/- 6.04 mu mol H-2 g(-1) dry weight after treatment with 25 mu M simazine under dark anaerobic condition for 2 and 24 h, respectively. This study demonstrates the potential of simazine for the enhancement of dark fermentative H-2 production by A. halophytica.

Automated summary

This study demonstrates the potential of simazine for enhancing dark fermentative H-2 production by A. halophytica.