Novel dynamic membrane, metabolic flux balance and PICRUSt analysis for high-rate biohydrogen production at various substrate concentrations

This research aimed to implement high-rate biohydrogen production using dynamic membrane at various substrate concentrations. Two identical dynamic membrane bioreactors (DMBRs) on the laboratory scale were equipped with polyester mesh of 444-mu m pore size. The DMBRs were continuously fed with glucose as a model substrate at 15, 20, and 25 g/L at hydraulic retention times (HRTs) of 2 h and 3 h. The DMBR enabled high-rate hydrogen production at both HRTs in long-term operation without backwashing. The peak average H2 production rate (HPR) and H2 yield (HY) per glucoseconsumed was 58.86 +/- 0.73 L/L-d and 2.00 +/- 0.04 mol H2/mol glucoseconsumed, respectively, with a feed glucose concentration of 20 g/L at 2 h HRT. At 3 h HRT, the highest HPR and HY were 29.81 +/- 1.01 L/L-d and 1.53 +/- 0.05 mol H2/mol glucoseconsumed with a feed glucose concentration of 20 g/L, respectively. HPR and HY were decreased in other feed concentration (15 g/L and 25 g/L) at each HRT, which was concomitant with metabolic flux shifted to lactic acid production and homoacetogenesis. Additionally, substrate consumption efficiency decreased at a feed concentration of 25 g/L. The microbial population at 20 g/L was dominated by Clostridium sp. and lactic acid bacteria. PICRUSt bioinformatics predicted the highest ferredoxin hydrogenase expression and LDH expression of Clostridium sp.

Automated summary

This research successfully achieved high-rate biohydrogen production at different substrate concentrations using dynamic membrane technology. The peak hydrogen production rate and yield were highest at a glucose concentration of 20 g/L, with a shift in metabolic flux observed at other concentrations.