杉木林土壤中固氮功能细菌的生长特性研究

Studies on the Growth Characteristics of Nitrogen-fixing Bacterium in Soil of Cunninghamia lanceolata Forest

[目的]研究固氮功能菌株的生长特性,探索适地适菌原则。[方法]本研究以103株固氮功能细菌为研究对象,以p H值及培养温度为考量指标,分别研究了8个温度梯度、10个p H值梯度对菌株生长的影响。[结果]表明:经检测,含有nif H基因的菌株有103株;菌株的最适生长条件为温度28℃、p H=7,各菌株的温度适宜生长区为20、28、37℃,大量菌株生长的适宜p H值为4、5、7、8;在低温、碱性土中的适用菌株为6003,在高温、碱性土中的适用菌株有09ul27、1010、2024、2029、7002、lk2-1c(2)和zk3-1,在酸性及碱性土中均适宜生长的菌株为1012和2025。根据菌群不同生长特性,对所有菌株进行非层次聚类,使用SSI算法得出最优分类为9类,其中,第5类和第7类全部属于伯克霍尔德属,第2类基本为芽孢杆菌属,其它类别中各菌属没有出现明显的聚类现象,且生长条件分类与菌种的初步鉴定分类没有明显的相关性。[结论]固氮功能菌株的适宜生长环境较一致,最适宜的生长条件为温度28℃、p H=7。筛选出适合在特殊环境生长的固氮功能细菌10株,各菌株初步鉴定为枯草芽孢杆菌、蜡样芽孢杆菌、巨大芽胞杆菌、Chitinophaga pinensis、Burkholderia xenovorans、Burkholderia phymatum、Burkholderia bannensis。通过生长条件聚类分析及所有菌株的16S r DNA鉴定比对得出,菌株的生长特性与其生物学特征不完全相关。

[ Objective ] To study the growth characteristics of functional strains and to explore the principles of suit- able bacteria. [ Method] In this study, the effects of 10 pH gradients and 8 temperature gradients on the growth of 103 strains of nitrogen-fixing bacteria were researched. [ Result] There were 103 bacterial strains containing nifH gene. The most suitable growth conditions of these strains were 28℃, pH = 7. The temperature ranges suitable for growth were 20, 28 and 37℃, the pH values were 4, 5, 7 and 8. The strain 6003 was suitable to grow in low tem- perature alkaline soil, while the strains 09u127, 1010, 2024, 029, 7002, lk2-1c （2） and zk3-1 were suitable to grow in high temperature alkaline soil. The strains suitable for growth in acid and alkaline soils were 1012 and 2025. According to the different growth characteristics of the bacteria, all the strains were classified into 9 categories by using SSI algorithm. Both the fifth and seventh categories belonged to Burkholderia, the second category be- longed to Bacillus. There was no obvious clustering phenomenon in the other categories, and there was no significant corrlation between the growth condition classification and the strains identification. [ Conclusion ] The suitable growth environment of the nitrogen-fixing bacteria is similar, and the most suitable growth conditions of these strains are 28~C, pH = 7. 10 strains of nitrogen-fixing bacteria suitable in special environment a~ screened out. These strains are initially identified as Bacillus subtilis subsp, Bacillus cereus, Bacillus megaterium, Chitinophaga pinensis, Burkholderia xenovorans, Burkholderia phymatum, and Burkholderia bannensis. The results also show that the growth characteristics of the strains are not completely cmTelated with their biological characteristics by growth condi- tion cluster analysis and 16S rDNA identification.