Indole acetic acid (IAA) is a plant growth-promoting hormone used in agriculture; therefore, its continuous production is of paramount importance. IAA-producing eight bacteria were isolated from the rhizosphere of Verbascum vulcanicum. Among them, Arthrobacter agilis A17 gave maximum IAA production (75 mg/L) and this strain was used to immobilization studies. The A. agilis A17 cells were immobilized in calcium alginate for the production of IAA. Optimization of process parameters for IAA production was carried out to enhance IAA production using immobilized cells. The maximal production of IAA was 520 mg/L under the following optimal conditions: 1% mannitol, 30 °C, pH 8.0, and 24 h incubation. It was determined that the immobilized cells could be reused (13 times) for the production of IAA.
Keywords: Arthrobacter agilis; Fermentation; Immobilized cells; Indole acetic acid.