Characteristics of endophytic bacteria, isolated from the roots of Ipomoea pes-caprae (L.)

Relevance. Endophytic bacteria live in the internal tissues of healthy plants and do not cause any harm to the host plant. They positively affect plants' growth and development and help them absorb nutrients from the environment. Endophytic bacteria protect plants from various phytopathogens due to the synthesis of phytohormones and contribute to converting insoluble mineral salts into a form accessible to plants. Studies on endophytic bacteria isolated from I.pes-caprae in Vietnam are not yet numerous. Purpose of the study. Isolate and characterize endophytic bacteria from the roots of Ipomoea pes-caprae. Identify promising strains. Material and methods. The objects of the study were I. pes-caprae roots isolated from plants collected in Thang Hai village, Tinh Hai commune, Tinh Gia district, Thanh Hoa province. Before isolating endophytic bacteria strains, root samples were thoroughly washed with distilled water and sterilized with mercuric chloride solution for 5 minutes. The homogenate was cultivated on Luria-Bertani nutrient medium. The IAA concentration from bacterial strains was determined by the method of Glickmann and Dessaux (1995). A quantitative determination of phosphate-dissolving activity was carried out by measuring the phosphate accumulation in the solution in which the strains under study were cultivated. Results. Fifteen strains of endophytic IAA-producing bacteria were isolated on LB nutrient medium supplemented with L-tryptophan. Three (TH10R, TH11T, and TH13T) strains with high IAA synthesizing ability (from 2.53 to 4.19 pg / ml) were selected. The phosphate-dissolving activity of these isolates ranged from 1.06 mg / L to 3.64 mg / L. The TH10R strain was superior to other strains in its ability to synthesize IAA and phosphate solubility and was identified as Bacilus mycoides and named Bacilus mycoides TH10R.