Abstract: The indole-3-acetic acid（IAA）-producing strains were preliminarily screened by using spread plate and Salkowski colorimetric method，and quantitative analysis of spectrophotometry was used to rescreen the strain with high IAA producing capacity. Three IAA-producing strains were isolated from the compost sample，and strain 29B showed the highest IAA productivity with the yield reached 54.73 μg/mL in 96 h of cultivation. Based on morphological observation，part of physio-biochemical characteristics and analysis of 16S rDNA gene sequences，the strain 29B was identified asCorynebacteriumstationis. The single factor tests were designed to optimize the IAA production of strain 29B. Results showed that the optimum culture conditions were as follows：initial pH value，7.0；inoculum amount（volume fraction），2%；shaking culture at 35 ℃ for 108 h. Under the optimal culture conditions，the yield of IAA reached up to 138.87 μg/mL，which was increased by 153.74% compared with that before optimization. These results would provide an experimental and theoretical basis for the application of strain 29B in agricultural production.

Key words: indole-3-acetic acid（IAA）, screening, optimization, compost