Influence of temperature and carbon sources on auxin biosynthesis by Rhodococcus erythropolis strain and their phytostimulating activity in urbanozem soil

Abstract

The aim of this research was to study the effect of temperature and carbon sources for synthesizing activity of Rhodococcus erythropolis VKM Ac-2017D strain on the mineral medium. Tryptophan at a concentration of 0,5 g/l was added as a precursor for indole-3-acetic acid (IAA) biosynthesis. Phytostimulating effect was shown in condition of soil experiment using lawn grass mixture ( Festuca rubra - 30%, Lolium perenne - 30%, Poa pratensis - 20%, Festuca rubra trichlorophylla - 15%, Festuca ovina - 5%). The strain of selected oil-degrading bacteria was able to produce IAA on both hydrocarbon and carbohydrates as carbon sources. The differences were found in the production of auxin that depended on temperature and types of C-substrate. When sucrose used as a carbon source the maximum in production of IAA was 34,3 µg/ml at the temperature of 15°C. When culturing microorganisms on hexadecane the highest concentration IAA (77,69 µg/ml ) was achieved at 25°C. The culture broth (supernatant) and native bacterial suspension had shown phytostimulating activity on the lawn grass (weight of plant biomass, germination) to compare to water and chemically synthesized IAA in condition of soil experiment.