Dark bio-hydrogen fermentation by an immobilized mixed culture of Bacillus cereus and Brevumdimonas naejangsanensis

Abstract

Based on the immobilized mixed culture technology, both the hydrogen production and synergy mechanism between Bacillus cereus A1 and Brevumdimonas naejangsanensis B1 were investigated. Different immobilization carriers were chosen. In terms of hydrogen yield and the multi-cycle use of the carriers in batch fermentation, corn stalk as carrier was found to be a better candidate than fiber material (polyester fiber) and activated carbon (AC). The obtained cumulative hydrogen production was 2205 mL/L within 180 h, significantly higher than that of the suspended fermentation. The average cumulative hydrogen production and hydrogen yield were 1845 mL/L and 1.50 mol H2/mol glucose for ten cycles of repeated fermentation batches respectively, which was 62.5% higher than that of suspended fermentation. The experimental results also showed that the system could use starch as direct substrate and the tolerance of the immobilized system to the substrate loading was improved. The activities of amylase and hexokinase were respectively 2 to 3 and 2 times higher than in the suspended fermentation due to the synergistic effect of co-immobilization compared with the suspended fermentation.