7株大豆根瘤菌噬菌体的分离及生物学特性的检测

ISOLATION AND CHARACTERIZATION OF SEVEN SOYBEAN RHIZOBIOPHAGES

Seven rhizobiophages infective against two strains of Sinorbizobium fredii and two strains of Bradyrhizobium japonicum were isolated in our country from field soils cropped to soybeans.These rhizobiophages were characterized by their morphology, host range, restriction endonuc-lease patterns,DNA melting temperature, DNA-DNA homologies. Elec-tron-microscopic observation indicated that these seven phages showed four morphotypes. These phages had a narrow host range. Restriction endonuclease analysis revealed that the seven rhizobiophages were dou-ble stranded DNA viruses varying considerably in their restriction endonuclease patterns. The G+C content of the DNAs ranged between 42.9 and 72.1 mol% as estimated from their melting temperatures. DNA-DNA hybridization experiments showed that the genomes of the seven phages could be provisionally divided into three groups by their degree of ho-mology with the probes derived from pfc ( a fast growing rhizobium ) and psm ( a slow growing rhizobinm ) .