Hosoda Akifumi, Sakai Masao, Kanazawa Shinjiro
Laboratory of Soil Microbiology, Department of Plant Resources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Biosci Biotechnol Biochem. 2003 May;67(5):1048-55. doi: 10.1271/bbb.67.1048.
Agar-degrading bacteria in spinach plant roots cultivated in five soils were screened, and four strains of Paenibacillus sp. were isolated from roots cultivated in three soils. The agar-degrading bacteria accounted for 1.3% to 2.5% of the total bacteria on the roots. In contrast, no agar-degrading colony was detected in any soil (non-rhizosphere soil samples) by the plate dilution method, and thus these agar-degrading bacteria may specifically inhabit plant roots. All isolates produced extracellular agarase, and could grow using agar in the culture medium as the sole carbon source. Zymogram analyses of agarase showed that all four isolates extracellularly secreted multiple agarases (75-160 kDa). In addition, the isolates degraded not only agar but also various plant polysaccharides, i.e., cellulose, pectin, starch, and xylan.
对在五种土壤中种植的菠菜植物根系中的琼脂降解细菌进行了筛选，从三种土壤中种植的根系中分离出了四株芽孢杆菌属菌株。琼脂降解细菌占根系总细菌的1.3%至2.5%。相比之下，通过平板稀释法在任何土壤（非根际土壤样本）中均未检测到琼脂降解菌落，因此这些琼脂降解细菌可能特异性地栖息于植物根系中。所有分离株均产生胞外琼脂酶，并且能够以培养基中的琼脂作为唯一碳源生长。琼脂酶的酶谱分析表明，所有四株分离株均在胞外分泌多种琼脂酶（75-160 kDa）。此外，这些分离株不仅能降解琼脂，还能降解各种植物多糖，即纤维素、果胶、淀粉和木聚糖。
