从水稻根、茎、叶、根际土壤及埋入土壤中的几丁质和纹枯病菌核中 ,分离出 2 5 6株拮抗菌。根据分离来源、生长速度、抑菌特性和几丁质活力等 ,选出 3株对纹枯病有较强抑菌力的代表性菌株进行混合培养试验。结果表明 :混合菌处理 6抑菌活性明显比单一菌种处理 2、 3高 ,其差异竟达 3倍以上 ;混合菌培养处理 4、处理 5及处理 7明显提高了生长速度和抑菌圈直径。混合培养单位含菌量有所提高 ,几丁质酶活性大多高于单菌培养 ,其中处理 6、 7几丁质酶活力在各组合间达极显著水平 ,表明各菌间无相互抑制作用。这对转变传统的使用单一菌株进行生物防治的观念有着积极的意义 ,并为下一步田间生物防治提供了理论依据 Antagonistic bacteria were isolated from the chitin and Rhizoctonia solani in rice roots, stems, leaves, rhizosphere soil and in soil. According to the sources of separation, growth rate, antibacterial properties and chitin activity, three representative strains with strong antibacterial activity against sheath blight were selected for mixed culture. The results showed that the antibacterial activity of mixed bacteria 6 was obviously higher than that of single strain 2 and 3, the difference was more than 3 times. The mixed bacteria culture treatment 4, treatment 5 and treatment 7 significantly increased the growth rate and inhibition zone diameter . Incubation of mixed culture units increased, chitinase activity were mostly higher than single culture, of which 6,7 chitinase activity reached a significant level in each combination, indicating that there is no mutual inhibition between the bacteria. This is of positive significance for transforming the traditional concept of using a single strain for biological control and provides a theoretical basis for the next field biological control