一株光合细菌的筛选及其产氢试验研究

发布时间：2018-05-31 19:53

本文选题：菌株筛选 + 产氢　；参考：《太原理工大学》2015年硕士论文

【摘要】：氢气热值高，燃烧产物清洁无污染，被认为是21世纪最具应用价值的可再生能源之一。与传统的电化学、热化学制氢方法相比，生物制氢有着节约能源、不消耗矿物资源、可持续等优点，其在研究与应用中的地位越来越受到重视，许多国家都投入大量的人力物力对其进行研究。在生物制氢研究中，光合细菌光发酵制氢因具有产氢效率高、底物转化效率高、对环境无污染等突出的优点，而日益受到人们的广泛关注。本实验利用光照富集以及双层平板划线法从污水厂二沉池的活性污泥中分离纯化得到一株光合细菌，结合菌落特征以及16SrDNA基因序列分析等对其进行了分类学鉴定，确定该菌株为沼泽红假单胞菌（Rhodopseudomonas palustris），命名为Rhodopseudomonas palustris.PB-Z。以所筛选的光合细菌PB-Z为研究对象，对其生长条件进行初步优化，并研究了PB-Z在不同氮源、碳源、氮源浓度、碳源浓度、初始pH值、镁离子浓度下的产氢特性。实验结果表明：（1）厌氧光照是PB-Z的最佳生长模式；乙酸钠为PB-Z生长的最佳碳源；在光照强度为4500lux、初始pH为7时，PB-Z的生长活性最高。（2）以尿素为氮源时，PB-Z有着最高的产氢活性，累积产氢量为91.2±4.5ml，尿素为PB-Z的最佳产氢氮源；在尿素浓度为10mmol/L时，PB-Z的产氢量最大，，为101.1±3.4ml。（3）PB-Z产氢的最佳碳源为葡萄糖，当葡萄糖浓度为70mmol/L时，PB-Z有着最大的产氢量与底物转化率，分别为123±3ml、69.7±1.9%。PB-Z的最大产氢活性出现在PB-Z的对数生长期。（4）PB-Z产氢的最佳初始pH为7，PB-Z在利用葡萄糖产氢的过程中，会产生有机酸使培养基变为酸性，通过外源调节培养基的pH能够显著提高光合细菌PB-Z的产氢量以及底物转化率，产氢量由124.7±2.7ml（对照组）提高到221.7±8ml，底物转化率由68.1%（对照组）提高到91.2%。（5）光合细菌PB-Z产氢的最适镁离子浓度为5mmol/L。PB-Z中含有多种色素，在一定的镁离子浓度范围内，PB-Z的色素合成状况良好，但是过高浓度的镁离子会对PB-Z的色素合成造成不利影响，光合色素合成受到抑制，PB-Z的产氢量出现显著地下降。为探究光合细菌PB-Z产氢的最适条件，根据单因素实验的结果，以镁离子浓度、pH、反应时间为实验因素，以光合细菌PB-Z产氢量为响应值，采用响应面分析法对实验结果进行模拟及分析，建立了产氢量与3个产氢影响因素关系的二次多项式数学模型。结果表明，镁离子浓度、pH值、反应时间与产氢量存在显著的相关性，确定PB-Z的最佳产氢条件为：镁离子浓度4.77mmol/L，初始pH7.05，反应时间77.5h，在此实验条件下，实际产氢量为137.8ml，与预测值相比偏差仅4.8%。说明响应曲面法优化PB-Z的产氢条件是可行的。
[Abstract]:Because of its high calorific value and clean combustion products, hydrogen is considered as one of the most valuable renewable energy sources in the 21st century. Compared with the traditional electrochemical and thermochemical hydrogen production methods, biological hydrogen production has the advantages of saving energy, not consuming mineral resources, and being sustainable, so it has been paid more and more attention in the research and application. Many countries have invested a lot of manpower and material resources to study it. In the research of biological hydrogen production, photo-fermenting hydrogen production by photosynthetic bacteria has attracted more and more attention for its advantages of high efficiency of hydrogen production, high conversion efficiency of substrate and no pollution to the environment. In this experiment, a photosynthetic bacteria was isolated and purified from activated sludge of secondary settling tank of wastewater treatment plant by the method of light enrichment and double layer plate drawing. The bacteria was identified by taxonomy combining with colony characteristics and 16SrDNA gene sequence analysis. The strain was identified as Rhodoppseudomonas palustris, named Rhodopseudomonas palustris.PB-Z. The growth conditions of photosynthetic bacteria (PB-Z) were preliminarily optimized, and the hydrogen production characteristics of PB-Z under different nitrogen sources, carbon sources, nitrogen source concentrations, carbon source concentrations, initial pH values and magnesium ion concentrations were studied. The results show that anaerobic illumination is the best growth mode for PB-Z, sodium acetate is the best carbon source for PB-Z growth, and the growth activity of PB-Z is the highest when the light intensity is 4500luxand and the initial pH is 7) when urea is used as nitrogen source, PB-Z has the highest hydrogen production activity. The accumulative hydrogen production was 91.2 卤4.5 ml, urea was the best hydrogen and nitrogen source for PB-Z, the hydrogen production of PB-Z was the largest when urea concentration was 10mmol/L, and the optimum carbon source of hydrogen production was glucose when the concentration of urea was 101.1 卤3.4ml.(3)PB-Z. When the concentration of glucose was 70mmol/L, PB-Z had the largest hydrogen production and substrate conversion. The maximum hydrogen production activity of 69.7 卤1.9%.PB-Z (123 卤3 ml) appeared in the logarithmic growth period of PB-Z. The optimum initial pH of hydrogen production of PB-Z was 7g PB-Z. In the process of hydrogen production from glucose, organic acids were produced to make the medium acidic. The hydrogen production and substrate conversion of photosynthetic bacteria PB-Z could be significantly increased by adjusting the pH of the medium. Hydrogen production increased from 124.7 卤2.7 ml (control group) to 221.7 卤8 ml, and substrate conversion rate increased from 68.1 ml (control group) to 91.22%. 5) the optimum magnesium ion concentration of photosynthetic bacteria PB-Z for hydrogen production was that 5mmol/L.PB-Z contained many kinds of pigments, and the pigment synthesis of PB-Z was good in a certain range of mg ~ (2 +) concentration. However, too high concentration of magnesium ions had a negative effect on the synthesis of PB-Z pigments, and the hydrogen production of PB-Z decreased significantly when the synthesis of photosynthetic pigments was inhibited. In order to explore the optimum conditions for hydrogen production of photosynthetic bacteria (PB-Z), according to the results of single factor experiments, the pH of mg ~ (2 +) and reaction time were taken as experimental factors, and the hydrogen production of photosynthetic bacteria (PB-Z) was taken as response value. The response surface analysis method is used to simulate and analyze the experimental results, and a quadratic polynomial mathematical model of the relationship between hydrogen production and three factors affecting hydrogen production is established. The results showed that there was a significant correlation between mg ~ (2 +) concentration, pH value, reaction time and hydrogen production. The optimum hydrogen production conditions of PB-Z were determined as follows: mg ~ (2 +) concentration 4.77 mmol / L, initial pH 7.05, reaction time 77.5 h. The actual hydrogen production is 137.8 ml, the deviation is only 4.8% compared with the predicted value. It is feasible to optimize the hydrogen production conditions of PB-Z by response surface method.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ116.2;Q93

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