Department of Agricultural Chemistry, College of Agriculture, University of Osaka Prefecture, Sakai 591, Japan.
Appl Environ Microbiol. 1986 Oct;52(4):911-4. doi: 10.1128/aem.52.4.911-914.1986.
Rhizobial cells attached or unattached to soil particles were estimated. Nonsterile soils into which antibiotic-resistant mutants of Bradyrhizobium japonicum had been introduced were fractionated by a centrifugation technique into two fractions: A, which contained mainly rhizobial cells attached to soil particles, and F, which contained mainly rhizobial cells unattached to them. Rhizobial counts decreased in both fractions during incubation of the soil at 30 degrees C, with a concomitant decrease in the proportion of the count of fraction F to that of fraction A. Sonication of fraction A of the soil incubated for more than 3 weeks caused an increase in the rhizobial count. The ratio of the count of fraction A estimated by the plant infection method to that estimated by the dilution plate method increased after 5 days of soil incubation. More than 90% of the indigenous rhizobia in an agricultural field existed in fraction A. These results suggest that the majority of rhizobial cells are attached to soil particles.
测定了附着或不附着于土壤颗粒的根瘤菌细胞。将已引入抗抗生素突变体的根瘤菌的非无菌土壤通过离心技术分离成两个部分：A 部分，主要包含附着于土壤颗粒的根瘤菌细胞；F 部分，主要包含不附着于土壤颗粒的根瘤菌细胞。在 30°C 下培养土壤时，两种部分中的根瘤菌计数都会减少，同时 F 部分的计数比例会降低到 A 部分的比例。对培养超过 3 周的土壤的 A 部分进行超声处理会导致根瘤菌计数增加。用植物感染法估计的 A 部分的计数与用稀释平板法估计的计数之比在土壤培养 5 天后增加。农业用地中 90%以上的土著根瘤菌存在于 A 部分。这些结果表明，大多数根瘤菌细胞附着于土壤颗粒。
