Abstract
In this study, 382 isolates of bacterial endophytes from tissues of plants grown in the foothills and piedmont plains of the Trans-Ili Alatau were isolated. It was found that certain strains actively produce indole-3-acetic acid (IAA) in a medium containing l-tryptophan. Among the strains studied, 26 strains (66%) showed a positive response to production of IAA. Bacteria synthesized IAA in the range of 18.6 ± 1.1 to 82.4 ± 2.3 µg/ml. IAA was synthesized more actively by Streptosporangium sp. KK1 (44.1 µg/ml), Rhodococcus sp. KK 2 (42.5 µg/ml), Streptomyces tendae KK3 (44.9 µg/ml) strains. The most active auxin's producer is a Jeotgalicoccus halotolerans BAK1 strain, whose total level of IAA production reached 82.4 µg/ml. Such strains as Streptomyces griseorubiginosis KK4, Streptomyces sp. KK5 and Jeotgalicoccus halotolerans BAK1 were found to have a significant stimulating effect which was reflected in the increase of the length of the roots of soybean and barley. As a result, 8 promising strains with fungicidal, growth-stimulating, phosphorus dissolving and enzymatic activities were selected for the further development of highly microbiological preparations for crop research.