Department of Horticulture and the Maryland Agricultural Experiment Station, University of Maryland at College Park, College Park, Maryland 20742-5611, and Soybean and Alfalfa Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705.
Appl Environ Microbiol. 1992 Jul;58(7):2137-43. doi: 10.1128/aem.58.7.2137-2143.1992.
The diversity of rhizobia that form symbioses with roots of black locust (Robinia pseudoacacia L.), an economically important leguminous tree species, was examined by inoculating seedling root zones with samples of soil collected from the United States, Canada, and China. Bacteria were isolated from nodules, subcultured, and verified to be rhizobia. The 186 isolates varied significantly in their resistance to antibiotics and NaCl, their growth on different carbohydrates, and their effect on the pH of culture media. Most isolates showed intermediate antibiotic resistance, the capacity to use numerous carbohydrates, and a neutral to acid pH response. Isolates had greater similarity within sampling locations than among sampling locations. The isolates were grouped by using numerical taxonomy techniques, and representative strains of 37 groups were selected. The mean generation times of these isolates ranged from 3 to 9 h, and the protein profile of each of the 37 isolates was unique. Nitrogen fixation, total nitrogen accumulation, and plant growth varied significantly among black locust seedlings inoculated with the representative isolates. We conclude that great variation exists among Rhizobium spp. that nodulate black locust, and selection of strains for efficiency of the symbiotic association appears possible.
通过用从美国、加拿大和中国采集的土壤样本接种幼苗根部，研究了与刺槐（Robinia pseudoacacia L.）根部共生的根瘤菌的多样性，刺槐是一种具有重要经济价值的豆科树种。从根瘤中分离出细菌，进行传代培养，并验证为根瘤菌。186 个分离株在抗生素和 NaCl 的抗性、对不同碳水化合物的生长能力以及对培养基 pH 值的影响方面差异显著。大多数分离株表现出中等抗生素抗性、利用多种碳水化合物的能力和中性到酸性 pH 值反应。分离株在采样地点内的相似性大于采样地点之间的相似性。使用数值分类技术对分离株进行分组，选择了 37 个组的代表性菌株。这些分离株的平均世代时间从 3 到 9 小时不等，37 个分离株的蛋白质图谱都是独特的。接种代表性分离株的刺槐幼苗的固氮、总氮积累和植物生长差异显著。我们得出结论，与刺槐共生的根瘤菌存在很大的变异，选择具有共生关联效率的菌株是可能的。
