Bacteria associated with the rhizosphere, rhizoplane and phyllosphere of soybean (Glycine max L.) Merrill

The goals of this study were to enumerate the heterotrophic bacteria that inhabit the rhizosphere, rhizoplane and phyllosphere of soybean over one growing season and to characterize and compare a random collection of bacterial isolates. The field study was conducted on an irrigated sandy loam soil. A total of 300 well-isolated bacterial colonies were randomly obtained from the plates in which the bacterial counts were made. All these strains were examined for 35 separate characteristics. Some bacterial properties were frequently detected such as the presence of catalase (100%), production of ammonia from asparagine, growth on Nfb medium, resistance to cycloheximide, molybdenum (100%) and penicillin but other characteristics were almost absent such as indole production, heat resistance to 60 degrees C and resistance to kanamicyn and rifamycin. The 200 bacteria obtained from rhizosphere and rhizoplane were clustered in five phena defined at 0.57 to 0.77 similarity level and the 100 strains recovered from phyllosphere were clustered in three phena formed at 0.53 to 0.61 similarity level. The addition of Gentian Violet to the modified Waksman medium increased the diversity of the isolated bacteria from the enviroments studied.