Experimental study on optimization of initial pH for photo-fermentation bio-hydrogen under different enzymatic hydrolysis of chlorella vulgaris

•The conditions of hydrogen production by Chlorella vulgaris were optimized.•Simplified the procedure of hydrogen production by Chlorella.•Reduced the cost of hydrogen production by Chlorella.•Chlorella solution has great potential for biological hydrogen production. In the paper, Use Chlorella as raw material, HAU-M1 Photosynthetic bacteria (PSB) as hydrogen-producing bacteria, the influence of initial pH on bio-hydrogen by photosynthetic organisms from Chlorella vulgaris with diverse enzyme addition was studied. The results showed that when using cellulase as hydrolase, the optimum initial pH was 7.0 and highest bio-hydrogen was 25.99 mL/g dry cell weight. Using neutral protease as hydrolase, the optimum initial pH was 8.0 and highest bio-hydrogen was 16.47 mL/g dry cell weight. Using mixed enzyme of cellulase and protease as hydrolase, the optimal initial pH was 7.0 and highest bio-hydrogen was 27.43 mL/g dry cell weight. The bio-hydrogen from Chlorella after mixed enzymatic hydrolysis is better than that of single enzymatic hydrolysis, we think the mixed enzymatic hydrolysis of cellulase and protease was superior to the single enzymatic hydrolysis of the two enzymes, which provides a scientific reference and low-cost bio-hydrogen technology by microalgae.