بررسی غلظت‌های مختلف تریپتوفان بر تولید ایندول استیک اسید توسط باکتری‌های حل‌کننده فسفات جداسازی شده از مزارع برنج استان مازندران

The objective of the present study was to evaluate of different concentrations (including, Zero, 0.5, 1, 2, 4, 6 mg/ml) of L-tryptophan on IAA production by phospate-solubilizing rhizobacteria isolated from rice paddy fields of Mazandaran province, Iran. Also, a part of this study focused on modeling the effect of L-tryptophan on the IAA production of these isolates. Generally, two of the most effective isolates from a total of 53 colonies were isolated for this experiment. A Gompertz model was used to quantify the response of PSB to different concentrations of L-tryptophan on IAA production (R2 > 0.98). Based on this model, the maximum production of IAA was 15.53 and 12.12 µg/ml after three days for M100 and M183 isolates, respectively. Also, these isolates showed maximum rate of IAA production at 2.5 mg/ml of L-tryptophan concentration. However, there were no significant differences between isolates based on their confidence limits and regression analysis. In conclusion, results of this study revealed that two mentioned isolates could not only solubilize the phosphorus but also were the efficient in terms of IAA production. Therefore, these isolates may be considered to be good candidates for biofertilizers production.