一个新的高温产氢菌及产氢特性的研究

A new hydrogen-producing strain and its characterization of hydrogen production

利用Hungate滚管技术从西藏山南地区热泉淤泥中分离到一株高温产氢的厌氧发酵细菌T42。菌株T42革兰氏染色反应为阴性,但KOH裂解试验证实其为革兰氏阳性杆菌。菌体大小为0.7μm^0.9μm×3.2μm^7μm,不运动,不产芽孢。其生长温度范围为32℃~69℃,最适生长温度为60℃~62℃,生长pH范围为5.0~8.8,最适生长pH为7.0~7.5,代时30min。有机氮源是T42菌株的必需生长因子。菌株T42利用淀粉、纤维二糖、蔗糖、麦芽糖、糊精、果糖、糖原和海藻糖等底物生长并发酵产氢,发酵葡萄糖的终产物为乙酸、乙醇、H2和CO2。G+C含量为31.2mol%。系统发育分析表明菌株T42与Thermobrachium celere和Caloramator indicus位于同一分支,生理生化特征也表明菌株T42应是Thermobrachium属的一个新菌株,在中国普通微生物菌种保藏中心的保藏号为AS1.5039。菌株T42的最佳产氢初始pH为7.2,最佳产氢温度为62℃,其氢转化率为1.06mol H2/mol葡萄糖,最大产氢速率为24.0mmol H2/gDW/h。20mmol/L的Mg2+和2mmol/L的Fe2+可分别提高菌株T42的产氢量20%和23.3%,而Ni2+对其产氢无明显的作用。当菌株T42和热自养甲烷热杆菌(Methanothermobacter thermautotrophicus)Z245共培养时,由于降低了氢分压,使其葡萄糖利用率和氢产量分别提高1倍和2.8倍,发酵产物乙酸和乙醇的比例也从1提高到1.7。

An anaerobic, thermophilic, hydrogen-producing strain T42 was obtained from a hot spring of South Mountain District, Tibet. Cells are Gram-positive, mobile rod-shaped. Spores were not observed. Temperature range for growth is 32℃ to 69℃ （optimum temperature, 60℃ - 62℃）, and pH range for growth is 5.0 to 8.8 （optimum pH, 7.0 - 7.5）. The generation time is around 30 min. Organic nitrogen source is required for growth. Strain T42 utilizes a wide range of carbohydrates, including starch, dextrin, sucrose, cellobiose, fructose, maltose, ribose, glycogen and galactose. Acetate, ethanol, H2 and CO2 are the end products of glucose fermentation. The （G ＋ C） content of strain T42 is 31.2mol%. Phylogenetic analysis based on the 16S rDNA sequence similarity indicates that strain T42 is the closest relative to Thermobrachium celere and Caloramator indicus. Biological characteristics and phyiogenetic analysis of the 16S rDNA gene indicate the new strain belongs to the genus Thermobrachium. Strain T42 produces H2 from glucose at maximal level when growing at 62% and initial pH 7.2, the hydrogen yields and maximal hydrogen production rate are 1.06mol H2/mol glucose and 24.0mmol H2/gDW/h, respectively. Strain T42 also produced H2 by fermentating from a variety of carbohydrates. 20mmol/L Magnesium and 2mmol/L iron increase the hydrogen production content by 20% and 23.3%, respectively, but nickel has no effect on the hydrogen production. In the co-culture of strain T42 and methane-producing strain M. thermautotrophicus Z245, hydrogen pressure is dramatically decreased, meanwhile deduced H2 production and the consumption of glucose are increased markedly by 2.8 fold and 1 fold, and the ratio of acetate/ethanol is enhanced from1 to 1 .7.