The detection and quantification of Indole -3 Acetic Acid (IAA) produced by Plant growth promoting rhizobacteria (PGPR) rely on a standard well-documented assay, which remains time-consuming, laborious, and costly. These drawbacks led to sway interest to economic and reliable assays. The aim of this work is to validate and standardize a fast, reliable, and cost-effective microassay to quantify IAA produced by bacteria with an easy microplate method. In order to validate the accuracy of the IAA microplate assay, bacterial samples from different genera were assayed using two methods: the conventional IAA estimation assay and the IAA micro- assay. The microassay shows a prominent reduction in used bacterial supernatant volume as well as Salkowski reagent volume of about 92.5%. It is considerably cheaper than the conventional one of around 56%. The newly performed microplate assay is 23 times faster. The result of IAA quantitative analysis for 13 bacterial strains showed that Bacillus muralis and Bacillus toyonensis produced the highest IAA concentration (23.64±0.003μg/ml and 23.35±0.006μg/ml, respectively). The obtained data from both methods were highly correlated with an R-value of 0.979. The microassay offers the ability to read the optical density of all samples simultaneously since used volumes of bacterial supernatants and Salkowski reagent were minimized to place the mixture in 96-well microplates, which reduces greatly required labor. Furthermore, the application of the IAA micro-plate assay reduces drastically the reagent waste and toxicity hazard of Salkowski reagent in the environment, thus, we can classify it as eco-friendly respecting the Green Chemistry concept according to Environmental Protection Agency (EPA). The IAA microassay is a, reliable, rapid and cost-effective and eco-friendly method to screen plant growth promoting potential of more than 23 bacterial strains by microplate. It could be an alternative for the conventional IAA assay as a routine research tool.

中文翻译：

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作为一种新的微调 PGPR 筛选试验的细菌 IAA 估计的微量测定验证

植物生长促进根际细菌 (PGPR) 产生的吲哚 -3 乙酸 (IAA) 的检测和定量依赖于标准的、有据可查的测定法，该测定法仍然耗时、费力且成本高。这些缺点导致人们对经济可靠的检测方法产生了兴趣。这项工作的目的是验证和标准化一种快速、可靠且具有成本效益的微量测定，以使用简单的微孔板方法量化细菌产生的 IAA。为了验证 IAA 微孔板测定的准确性，使用两种方法对来自不同属的细菌样品进行了测定：常规 IAA 估计测定和 IAA 微量测定。微量测定显示使用的细菌上清液体积和 Salkowski 试剂体积显着减少约 92.5%。它比传统的大约 56% 便宜得多。新进行的微孔板检测速度提高了 23 倍。13株菌株的IAA定量分析结果表明，壁芽孢杆菌和丰盛芽孢杆菌产生的IAA浓度最高（分别为23.64±0.003μg/ml和23.35±0.006μg/ml）。从这两种方法获得的数据与 0.979 的 R 值高度相关。由于细菌上清液和 Salkowski 试剂的使用量被最小化以将混合物置于 96 孔微孔板中，因此微量测定能够同时读取所有样品的光密度，从而大大减少了所需的劳动力。此外，IAA微孔板检测的应用大大减少了Salkowski试剂在环境中的试剂浪费和毒性危害，因此，根据环境保护署 (EPA)，我们可以将其归类为符合绿色化学概念的环保型产品。IAA 微量测定是一种可靠、快速、经济且环保的方法，可通过微孔板筛选超过 23 种细菌菌株的植物生长促进潜力。它可以替代传统的 IAA 检测作为常规研究工具。