Institute of Biology, Sylvius Laboratory, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands.
Arch Microbiol. 2013 Jan;195(1):9-17. doi: 10.1007/s00203-012-0842-x. Epub 2012 Sep 7.
Twenty endophytic bacteria were isolated from surface-sterilized stems and roots of cucumber plants. After removal of potential siblings and human pathogens, the remaining seven strains were identified based on their 16S rDNA as Pseudomonas fluorescens (2 strains) and P. putida (5 strains). Three strains, namely P. fluorescens CS1, P. fluorescens CR2 and P. putida CR3, were able to suppress tomato foot and root rot (TFRR). Special attention was paid to the characterization of the BIOLOG carbon oxidation profiles of the isolated pseudomonads in order to identify nutrients which might be important for their endophytic lifestyle. Comparative analysis of the profiles of these seven strains with those of seven rhizospheric Pseudomonas spp. revealed that endophytes were able to oxidize L-arabinose and 2,3-butanediol significantly more often than the rhizospheric group. An independent growth experiment performed in tubes using L-arabinose and 2,3-butanediol as sole carbon sources showed the same results as seen using BIOLOG for L-arabinose, but not for 2,3-butanediol. Since L-arabinose is one of the most abundant sugars in xylem of cucumber plants and was not detected in their rhizosphere, our data suggest that utilization of L-arabinose might be a trait contributing to the endophytic lifestyle of the isolated Pseudomonas endophytes.
从表面消毒的黄瓜植物茎和根中分离出 20 种内生细菌。在去除潜在的兄弟姐妹和人类病原体后，根据 16S rDNA 将剩余的 7 株菌株鉴定为荧光假单胞菌（2 株）和恶臭假单胞菌（5 株）。3 株菌株，即荧光假单胞菌 CS1、荧光假单胞菌 CR2 和恶臭假单胞菌 CR3，能够抑制番茄脚腐病和根腐病（TFRR）。特别注意了分离出的假单胞菌的 BIOLOG 碳氧化谱的特性，以确定其内生生活方式可能重要的营养素。这 7 株内生假单胞菌与 7 株根际假单胞菌的碳氧化谱进行了比较分析，结果表明，内生菌比根际组更能氧化 L-阿拉伯糖和 2,3-丁二醇。在试管中使用 L-阿拉伯糖和 2,3-丁二醇作为唯一碳源进行的独立生长实验，与 BIOLOG 用于 L-阿拉伯糖的结果相同，但不适用于 2,3-丁二醇。由于 L-阿拉伯糖是黄瓜植物木质部中最丰富的糖之一，而在其根际中未检测到，我们的数据表明，利用 L-阿拉伯糖可能是导致分离的假单胞菌内生菌内生生活方式的特征之一。
