This study investigates the optimization of various environmental and nutritional factors for the best indole acetic acid (IAA) producing isolate using Box-Behnken Design (BBD) with Response Surface Method (RSM) and examines its effects on early plant growth parameters of Cicer arietinum (chickpea). Firstly, the screening of putative Bacillus isolates based on IAA producing capability and analysis of other plant growth promoting attributes was carried out. The highest IAA producing isolate MRN16 was selected to optimize IAA production based on the BBD and a total of 86 sets of experiments were finalized. The incubation temperature of 35 °C, pH of 7.0, incubation time of 8 days, 1.0 g/L tryptophan, 20 g/L starch, 0.5 g/L KNO₃, were found the optimal conditions for the maximum IAA production. The extracted or purified IAA was examined by thin layer chromatography (TLC), showed a red colored spot with an 0.75 Rf value. IAA was determined using high-performance liquid chromatography (HPLC) and peak was observed at 6.66 min retention time, comparable with the standard IAA. The greenhouse assay confirmed that MRN16 was a significant isolate for enhancing chickpea vegetative growth parameters such as root/shoot length and weight (fresh/dry). Finally, isolate MRN16 was identified as Bacillus altitudinis using 16S rRNA sequencing. The present research establishes successful use of RSM, as an easy and useful tool to determine the optimized parameters for maximum IAA production in bacteria and further the utilization of bacteria to upsurge the plant growth.

本研究使用响应表面方法（RSM）进行Box-Behnken设计（BBD），研究了产生最佳吲哚乙酸（IAA）的最佳分离菌株的各种环境和营养因素的优化，并研究了其对Acerinum（Cicer arietinum）早期植物生长参数的影响鹰嘴豆）。首先，基于IAA生产能力筛选了推定的芽孢杆菌，并分析了其他促进植物生长的特性。选择了产生IAA最高的分离株MRN16，以基于BBD优化IAA的生产，并最终完成了86组实验。孵育温度为35°C，pH值为7.0，孵育时间为8天，色氨酸1.0 g / L，淀粉20 g / L，KNO ₃ 0.5 g / L发现了最大IAA产量的最佳条件。通过薄层色谱法（TLC）检查提取的IAA或纯化的IAA，显示出红色斑点，Rf值为0.75 。使用高效液相色谱（HPLC）测定IAA，在与标准IAA相当的保留时间6.66分钟处观察到峰。温室试验证实，MRN16是增强鹰嘴豆营养生长参数（例如根/茎长和体重（新鲜/干））的重要分离物。最终，分离株MRN16被鉴定为枯草芽孢杆菌使用16S rRNA测序。本研究建立了RSM的成功使用，它是一种简单而有用的工具，可以确定细菌中最大IAA产生的优化参数，并进一步利用细菌来促进植物生长。