Fermentative Hydrogen Production with Xylose by Clostridium sp. HR-1 Isolated from Cow Dung Compost

Abstract:

A anaerobic hydrogen-producing strain HR-1 was isolated from compost. Phylogenetic analysis based on 16S rRNA sequence similarity indicates that strain HR-1 is the closest relative to Clostridium acetobutylicum ATCC 824, with the similarity of 96%. Biological characteristics and phylogenetic analysis of 16S rRNA gene indicate that HR-1 is a new species named Clostridium sp. HR-1. Cells are Gram-positive, mobile rod-shaped. Spores and flagellums were no observed. Temperature range for growth is 10°C to 45°C (optimum temperature 37°C~39°C), and range pH for growth is 4.0 to 10.0 (optimum pH 7.5~8.0). H2, CO2, acetate, butyrate and a little ethanol are the end products of PYG fermentation. Strain HR-1 has the ability to use organic nitrogen and inorganic nitrogen sources for growth and hydrogen production, and yeast extract is the optimum nitrogen source for hydrogen production. Strain HR-1 produces hydrogen from xylose (3 g/L) at 37°C and initial pH 6.5, the hydrogen yields and maximal hydrogen production rate are 1.84 mol-H2/mol-xylose and 10.52 mmol-H2/h·g-cdw, respectively. Strain HR-1 is able to utilize glucose, galactose, fructose, mannose and cellobiose for hydrogen production and the hydrogen yields from glucose is 2.36 mol-H2/mol-glucose.

Key words:Fermentative hydrogen production, Isolation and characterization, Clostridium sp. HR-1, Xylose