中文摘要：

文章通过培养的方法分析了小麦根际微生物的群落结构以及对常用畜禽用抗生素的敏感性，研究结果表明，小麦根际土壤微生物总数为5．251×10^8cfu／g，其中细菌占绝对优势，占总菌数的99．04％，放线菌占0．09％，真菌占0．06％。从中分离出10株优势细菌，经过分子生物学鉴定均与芽孢杆菌属（Bacillus）亲缘关系较近。这10株优势菌对土霉素和四环素的敏感性研究结果表明，大部分菌株对土霉素的敏感性高于四环素，不同的菌株对同一种抗生素的敏感性差异较大。10株菌对土霉素的敏感浓度在10-100μg／L之间，对四环素的敏感浓度在100-500μg／L之间。

英文摘要：

The impact of widely-used veterinary antibiotics on soil environment was studied. Results reveals that the rhizospheric microorganism of wheat is dominated by bacteria accounting for 99.04%, others being actinomyces and fungi. 10 strains of the dominant bacteria were isolated, which were classified and identified as the species of genus Bacillus. It was found that most of them were more sensitive to terramycin than to tetracycline, and there exist rather wide differences of sensitivity to a certain antibiotics among the isolated bacterial strains. As far as the concentrations of the studied antibiotics, bacteria＇s 100-500μg/L.