EXTRACTION AND EVALUATION OF INDOLE ACETIC ACID FROM INDIGENOUS AUXIN- PRODUCING RHIZOSPHERE BACTERIA

Auxins are the phytohormones which play vital role in the growth and development of plants. Among the plant growth promoting rhizobacteria, some bacterial strains can synthesize auxins and help in plant growth stimulation. The present work deals with auxin production potential of the bacterial strains. Eighteen auxin-producing rhizobacteria were isolated and phylogenetically analyzed through 16S rDNA sequencing for identification. The isolated bacterial strains had shown similarity to various genera including Enterobacter , Bacillus , Halomonas , Cronobacter , Exiguobacterium , Kushneria and Arthrobacter spp. Isolates were also characterized morphologically, biochemically and physiologically. Most of the bacterial strains synthesized higher amounts of auxin during stationary phase of their growth. Bacterial auxin synthesis was monitored by varying concentrations of the precursor i.e., L-Tryptophan ranging from 200 to 1200 µgml -1 . The present study revealed variation in the auxin production potential of bacteria belonging to various genera with different phases of their growth and varying amount of Tryptophan available, thus, improved our insight regarding microbial auxin synthesis with reference to their growth and phylogeny which will be helpful in better exploitation of bacterial indole acetic acid (IAA) for phyto-stimulation.