中文摘要：

采用红外光谱和元素分析,初步研究了纯培养条件下水华鱼腥藻（一种常见蓝细菌）不同生长期的菌体和胞外代谢物以及作为唯一基质形成的菌体混合物的结构特征。结果表明：蓝细菌样品的红外光谱图中均没有1 720 cm-1峰。2 926/1 650比值显示,水华鱼腥藻对数生长期与衰亡后期的菌体芳香物质含量高,复杂度与土壤富里酸接近,但低于土壤胡敏酸;微生物处理能使菌体混合物具有更多芳香族物质,但1 530 cm-1峰消失,表明部分C=C及氨基酸类物质被分解。相对于土壤腐殖物质,水华鱼腥藻菌体的H/C比值及（O＋S）/C比值均较大,即缩合度较低而氧化度较高;经微生物处理后,其缩合度进一步降低,氧化度升高。总之,本实验条件下蓝细菌自发形成腐殖物质的可能性较低,且其作为唯一基质在其他微生物作用下形成的菌体混合物与土壤腐殖物质在结构上存在差距,但从蓝细菌的组成与结构上看,其可为腐殖物质的形成提供物质条件。该结果为土壤腐殖物质的形成研究与起源探索提供了一定的科学依据。

英文摘要：

【Objective】Cyanobacteria are the oldest photoautotrophic organisms on the earth. As they lived commonly in the ancestral protohydrosphere and entered into the geosphere with geological changes,they got profoundly involved in the formation of primitive soil humic substances（HS）. Since contain large volumes of protein,polysaccharide and even some humic-like acid substances in their cells,extra-and intracellular metabolites,is it possible for cyanobacteria cells to form HS spontaneously？ If the formation process needs catalysis of some microorganisms,what are the differences between different groups of microorganisms in role in the process？ These scientific problems need to be solved. 【Method】 In view of the above-mentioned scientific problems,this research adopted the source control and shake-flask liquid axenic culture method to get axenically cultured samples of Anabaena flos-aquae,a representative species of cyanobacteria,in different growth stage and products of Anabaena flos-aquae used as the only substrate and treated with different microbes. The products were analyzed for structural characteristics,using the method of element composition and fourier transform infrared spectroscopy（FTIR）,with a view to exploring possibility of cyanobacteria spontaneously forming HS or acting as substrate in HS formation and hence to make up and specifying the role of cyanobacteria in the origination and formation of soil HS. 【Result】The following findings were obtained. Under the experimental conditions,Anabaena flos-aquae had a long life cycle and remained quite constant in carbon content during their growing period. However,during the logarithmic phase,the carbon content in the thallus was relatively high,while in the extracellular metabolites it rose steadily but remained much lower than that in the thallus. None of the FTIR spectra of the cyanobacteria samples showed any peaks characteristic of the carboxyl C=O bonds at 1 720 cm-1,instead,the spectra intensified somewhat at 1 650 cm-1 and 1 530 cm-