[Auxin production by Klebsiella planticola strain TSKhA-91 and Its Effect of development of cucumber (Cucumis sativus L.) Seeds].

Capacity of Klebsiella planticola strain TSJhA-91 for synthesis of indolyl-3-acetic acid (IAA) and other auxins was studied. The qualitative and quantitative composition of these compounds depends on the presence of exogeneous tryptophan and on the nitrogen source. The highest IAA yield was obtained at the stationary phase of growth. Addition of L-tryptophan to the medium resulted in a significant increase (up to 85.5 microg/mL) of auxin biosynthesis, especially in the presence of nitrates. Thin-layer chromatography revealed that the indole-3-acetamide pathway was not active in this strain. The biological activity of auxins was confirmed by plant assay with the kidney bean cuttings; the height of root formation and rdot number increased 16- and 6-fold, respectively. Under conditions of low-temperature stress, protective effect of K. planticola TSKhA-91 on development of cucumbers (Cucumissativus L.) seeds, including stimulation of germi- nation and root formation by its seeds were shown.