微生物学
生物能源生物能源
    能源危机与环境污染问题受到人们越来越多的关注，开发新的能源体系已成为世界各国的共识。氢由于其本身无色、无嗅、无毒且燃烧后仅生成水而被认为是理想的清洁能源。另外，氢的能量密度高，其热值为143 MJ/kg，约为石油热值的3 倍；它能以气态、液态或固态金属氢化物的形式储存，能满足储运及各种应用环境的不同要求。因而“氢经济”成为各国经济发展规划的重要组成部分。
    本研究对高温环境的样品进行分离，通过初筛和复筛，选出一株产氢性能稳定且活性较高的菌株。通过对菌株的形态结构、生理生化特征及16S rRNA基因序列进行分析，鉴定该菌株为阪崎肠杆菌（Enterbacter sakazakii）。分析了pH值、碳源、菌体密度、温度、起始糖浓度、起始氧浓度等因素对菌株产氢活性的影响。通过对影响阪崎肠杆菌HP产氢活性主要因素的正交实验，确定该菌株批次发酵产氢的最佳条件为：起始pH值8.0，以葡萄糖为碳源，温度为35 ℃，起始氧浓度为0%。最高产氢速率可达5.5 mmol/h×mg dw。
    利用气相色谱仪对阪崎肠杆菌和克雷伯氏菌（Klebsiella oxytoca）HP1发酵产氢36h后的废液中所含脂肪酸进行检测，结果表明，阪崎肠杆菌发酵36h后废液中乙酸浓度为2.22μg/mL，丁酸浓度为3.33μg/mL；克雷伯氏菌的发酵产氢废液中乙酸浓度为0.66μg/mL，丁酸浓度为11.79μg/mL。
    光合细菌可利用乙酸、丁酸等有机酸进行光发酵产氢。在本研究中，将荚膜红假单胞菌（Rhodopseudomona capsulata）CN1接种于阪崎肠杆菌和克雷伯氏菌发酵产氢的混合废液中进行光发酵产氢，结果表明，在12d时产氢量达到最大，每毫升发酵废液可产生0.12mmol氢气。即暗发酵-光发酵联合产氢过程对氢的转化率有一定的提高，为暗发酵-光发酵联合产氢的研究奠定一定的基础。 [英文摘要]：     As the economy develops, the energy source problem and the environmental issue are paid more and more attention. Developing new energy system has become basic. Many of the countries are concerning about the development of the new energy system. Hydrogen energy has been considered as one of the most ideal future energies as it is clean, pollution-free, high heat value and easily storage and transportation. “Hydrogen economy” becomes an important part of program for economic development of many countries therefore.
    In this study, a high-efficient hydrogen producing strain has been isolated from the hot spring. It was identified as Enterbacter sakazakii by analysis of morphology, physiology and 16S rRNA gene sequence. Varies factors (e.g. pH, carbon sources, glucose concentration, temperature, O2 proportion and cell density) which influences the H2-production were investigated. After orthogonal experiment, the optimal conditions for hydrogen production were achieved as: initial pH value 8.0, using glucose as carbon sources, temperature 35℃, oxygen concentration 0%. In the batch fermentative hydrogen production, the maximal hydrogen production was obtained as 5.5mol/h•mg dw.
    The organic acid components of wastewater after dark-fermentative hydrogen production were analysed in this study. After 36 hours fermentation, the wastewater from Enterbacter sakazkii HP mainly contained acetic acid with a concentration of 2.22μg/mL and butyric acid with concentration of 3.33μg/mL. The wastewater from Klebsiella oxytoca HP1 mainly contained. The acetic acid’s concentration in Klebsiella oxytoca HP1’s wastewater was 0.66μg/mL and the butyric acid’s concentration in it was 11.79μg/mL.
    The hydrogen can be produced by the photosynthetic bacteria (PSB) using acetic acid and butyric acid in the process of photofermentation. In this research, the pH value of the fermentative wastewater of Enterbacter sakazkii HP and Klebsiella oxytoca HP1 was adujsted to 7. The wastewater was then inoculated with Rhodopseudomona capsulate CN1. An elementary experiment about PSB which used anaerobic fermentative wastewater to produce hydrogen was done. As a result, the maximum value of photofermentative hydrogen production was found to be 0.12mmol H2/ml wastewater. This research proves that the method is useful for hydrogen transformation.