Enhanced biohydrogen production from nutrient-free anaerobic fermentation medium with edible fungal pretreated rice straw

Abstract

An edible fungal pretreatment of rice straw was proposed for enhanced hydrogen production while reducing the chemical cost for traditional biological hydrogen production from lignocellulose. In this research, rice straw was pretreated by edible fungus Gymnopus contrarius J2 at room temperature under static conditions for 15 d at first. The highest hydrogen yield of 5.71 mmol g⁻¹-pretreated rice straw was obtained, 74% higher than the counterpart without pretreatment. Chemical composition analysis demonstrated that lignin removal was up to 22.4% with a little cellulose and hemicellulose loss of 13.3% and 17.1%, respectively, which is in favor of hydrogen production. Additionally, microscopic structure observation combined with FT-IR and XRD analysis illustrated the structural disruption of pretreated rice straw, and the crystalline index of rice straw can be decreased by 46.2% after pretreatment, which might account for the hydrogen production enhancement. The results also indicated that the hydrogen yield from pretreated rice straw was not affected without the addition of yeast extract and vitamins to the culture medium, which is substantial evidence that edible fungal pretreated rice straw could provide prerequisite nutrients for hydrogen-producing bacteria. Overall, edible fungal pretreatment has great potential under the mild conditions for high hydrogen yields and thus leads to a new direction to realize a highly efficient and economically competitive biological hydrogen production process from lignocellulosic biomass.