木糖发酵产氢菌的筛选及其生长产氢特性研究

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

利用改进的Hungate厌氧技术,从牛粪堆肥中分离出一株能有效利用木糖发酵产氢的中温菌HR-1。通过16S rRNA系统发育树分析表明,菌株HR-1与丙酮丁醇梭菌Clostridium ace-tobutylicum ATCC824相似性最高为96%,结合生理生化和生长特性分析表明,HR-1是梭菌属Clostridium的一个新种,命名为Clostridium sp.HR-1。菌株HR-1为单胞生长的规则杆状菌(0.3μm～0.6μm)×(1.4μm～2.3μm),革兰氏染色为阴性,无荚膜、无鞭毛、表面光滑、无明显凸起,专性厌氧菌。HR-1可在10°C～45°C,pH4.0～10.0条件下生长;37°C和pH8.0分别为其最适生长条件。发酵PYG的主要发酵产物有氢气、二氧化碳、乙酸、丁酸及少量乙醇。HR-1可以利用有机氮源和无机氮源生长并产氢,酵母提取物是其最佳产氢氮源。HR-1在木糖浓度为3g/L和初始pH6.5条件下,其比产氢量为1.84mol-H2/mol-木糖,最大比产氢速率为10.52mmol H2/h·g-细胞干重。HR-1可以亦利用葡萄糖、半乳糖、纤维二糖、甘露糖和果糖等碳源生长并发酵产氢,发酵葡萄糖时比产氢量为2.36mol-H2/mol-葡萄糖。

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℃to 45℃ （optimum temperature 37℃-39℃）, and range pH for growth is 4.0 to 10.0 （optimum pH 7.5-8.0）. HE, 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℃ and initial pH 6.5, the hydrogen yields and maximal hydrogen production rate are 1.84 mol-H2/mol-xylose and 10.52 mmol-H/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.