Effects of L-cysteine and giant panda excrement on hydrogen production from cassava residues

This study investigated the anaerobic hydrogen production from cassava residues using the mixed culture from giant panda (Ailuropoda melanoleuca) excrement. The FTIR and XRD results demonstrated that cassava residues could be degraded by the anaerobic mixed culture from grand panda excrement, and that maximum H₂ production rate (R_max) and the maximum cumulative H₂ production (H_max) and were 152.86 mL·L^–1·h^–1 and 688.36 mL·L^–1 respectively in the dark fermentation. The effects of L-cysteine on H₂ production, substrate utilization, metabolites distribution and biomass were studied in batch-mode tests. The results showed that the cassava residues were degraded by 31.6% through H₂ production. After adding L-cysteine (0.5–2.0 g·L^–1) to the nutrient solution, the biomass concentration reached to 1.53 g·L^–1, about 1.36 times higher than that of the control group without L-cysteine addition, and the dark fermentative H₂ production was 1.6–2.0 times higher than that of the control group. Our results demonstrated that by using the anaerobic mixed culture from giant panda excrement, cassava residues could be converted into H₂ efficiently with the addition of L-cysteine during the dark fermentation.