Seleksi Galur Bradyrhizobium japonicum Indigenos Toleran Media Asam Alumunium

Abstract

Twenty five indigenous strains of Bradyrhizobirrm jnponicum were screened employing acid-Alaminium media, in whkh 50 pM AI(K Al (S04)2.12H20) was added and pH adjusted to pH 4.5. Nine strains which are acid tolerance grew well with compact colonies after 10 days of incubation. Tbe selected strains, which were able to grow in Keyser-Munns media containing 50 pM Al, 200 pM Me, 50 pM Ca, 5 pM P and pH 4.5, showed an extended lag phase. Only two of them were able to reach an optical density of lo6-10' cells/ml in less than two weeks. Those two strains designated as tolerant to acid and aluminium were able to rise the pH of growth media as well as to produce ammonium as an alternative way to overconle toxicity of the stress media.