两株茶树内生草螺菌的微生物学特性

Microbiological properties of two endophytic bacteria isolated from tea (Camellia sinensis L.)

摘要:

摘要:【目的】从健康茶树叶片内分离两株内生乳白色短杆菌(编号WT00C和WT00F)并进行微生物学特性调查。【方法】通过细菌培养和染色的方法进行了形态观察;通过微生物生理生化分析的方法进行了生物活性测定，还进行了16S rDNA序列分析以及生理生化特性调查;通过系统发育学分析及各项指标的比较，确定两个菌株的分类归属。【结果】两株细菌菌落形态为圆形、不透明、乳白色、中央隆起、边缘整齐。菌体呈杆状，大小为(0.5－0.7)μm×(1.4－1.8)μm，有鞭毛，无芽孢，革兰氏染色阴性，产生IAA、NH4 + 和嗜铁载体但无固氮酶活性。WT00C和WT00F菌株产生IAA量分别为18.7±1.2 mg/L和24.9±1.5 mg/L。除不能利用丙酸盐外，它们的生理特征与伯杰氏手册中草螺菌属生化指标中的可利用碳源情况基本一致，并且与已鉴定的13种草螺菌的16S rDNA高度同源，相似度达99%。基于16S rDNA序列的系统发育学分析结果显示，两株细菌形成一个独立的分支，与已报道的13种草螺菌聚类并保持着一定的距离，两个菌株的生理生化特征与其它草螺菌有许多共性但存在明显的差别。【结论】分离获得的两株茶树内生细菌WT00C 和WT00F为草螺菌属的新菌株。

Abstract:

Abstract:［Objective］We investigated biological activities，physiological and biochemical properties of two endophytic bacteria isolated from fresh leaves of tea plants．［Method］ We did morphological observation，biological activity test，physiological and biochemical assays，16S rDNA analysis，and compared their genotype and phenotype with those of 13 Herbaspirillum species．［Results］Their colonies were round，opaque，central uplift and regular edge with a milky white color． Their cells were Gram-negative，rod-shaped with the size of (0.5－0.7) mm×(1.4－1.8) mm and flagellers，but without spore．Both isolates produced indole-3-acetic acid (IAA) (18.7 mg/L for WT00C and 24.9 mg/L for WT00F)，ammonia and siderophores，but no nitrogen-fixing activity．The 16S rDNA had sequences similarities of 99.7% each other and 99% with 13 Herbaspirillum species. Two isolates used carbon source as described in the genus Herbaspirillum，except for propionate salt．The neighbor-joining tree built using the 16S rDNA showed that two isolates formed an independent group，which kept certain genetic distance from the 13 Herbaspirillum species. Their physiological and biochemical characteristics and genotypes were different from those for 13 Herbaspirillum species.［Conclusion］Two isolates WT00C and WT00F were classified as novel members in the genus Herbaspirillum.