M. Nabrdalik
University of Opole, Independent Chair of Biotechnology and Molecular Biology Opole, PL

PRODUCTION OF INDOLE ACETIC ACID BY ENDOPHYTIC BACILLUS STRAINS


The objectives of this study were to isolate and characterize endophytic bacteria from sugar beet roots focusing on their ability to produce indole acetic acid (IAA). In order to isolate endophytic bacteria the sugar beet roots were used. To determine the amounts of IAA produced by endophytic Bacillus strains (B. amyloliquefaciens BC-220, B. megaterium BC-26, B. subtilis BC-4, B. subtilis BC-234), a colorimetric technique was applied with Salkowski reagent. The isolates were grown in Laurin Broth medium supplemented with L-tryptophan over the concentration range of 100-10000 µg/cm3 and incubated at 30°C for 7 days. The highest concentration of IAA was recorded after 4 days of culturing in the supernatant obtained from the media containing 10000 µg/cm3 of tryptophan. For the strain B. subtilis BC-4 the concentration of IAA marked in the post –culturing liquid amounted 12.93 µg/cm3, and for the B. amyloliquefaciens BC-220 strain it amounted over 8.39 µg/cm3. The strains Bacillus under study produced IAA in a different amount in the presence of L-tryptophan and in its absence.

Keywords: Bacillus, endophytes, tryptophan, auxins