State Key Laboratory of Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
Biotechnology Research Department, Department of Research and Innovation, Ministry of Education, Kyaukse, Myanmar.
BMC Microbiol. 2019 Jul 8;19(1):155. doi: 10.1186/s12866-019-1528-1.
Indole-3-acetic acid (IAA) is produced by microorganisms and plants via either tryptophan-dependent or tryptophan-independent pathways. Herein, we investigated the optimisation of IAA production by Streptomyces fradiae NKZ-259 and its formulation as a plant growth promoter to improve economic and agricultural development.
The maximum IAA yield achieved using optimal conditions was 82.363 μg/mL in the presence of 2 g/L tryptophan after 6 days of incubation. Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) analysis of putative IAA revealed an RF value of 0.69 and a retention time of 11.842 min, comparable with the IAA standard. Regarding product formulation, kaolin-based powder achieved a suspension rate of 73.74% and a wetting time of 80 s. This carrier exhibited good shelf life stability for NKZ-259, and the cell population did not decrease obviously over 4 months of storage at 4 °C. In vivo analysis of plant growth promotion showed that tomato seedlings treated with kaolin powder containing NKZ-259 cells displayed a significant increase in root and shoot length of 7.97 cm and 32.77 cm, respectively, and an increase in fresh weight and dry weight of 6.72 g and 1.34 g. Compared to controls, plant growth parameters were increased almost it two-fold.
Optimising the culture conditions resulted in an almost four-fold increase in IAA secretion by NKZ-259 cells. The results clearly demonstrate that S. fradiae NKZ-259 holds great potential for plant growth promotion and IAA production. Furthermore, kaolin-based powder is an effective carrier for NKZ-259 cells and may be useful for commercial applications.
吲哚-3-乙酸（IAA）是微生物和植物通过色氨酸依赖或非依赖途径产生的。在此，我们研究了优化链霉菌 NKZ-259 生产 IAA 的条件，并将其配制成植物生长促进剂，以促进经济和农业发展。
在 6 天的培养过程中，在 2g/L 色氨酸存在的情况下，最佳条件下 NKZ-259 的 IAA 产量最高可达 82.363μg/mL。薄板层析（TLC）和高效液相色谱（HPLC）分析推测的 IAA 显示出 0.69 的 RF 值和 11.842min 的保留时间，与 IAA 标准相当。关于产品配方，基于高岭土的粉末达到 73.74%的悬浮率和 80s 的润湿时间。该载体对 NKZ-259 具有良好的货架期稳定性，在 4°C 下储存 4 个月，细胞数量没有明显减少。体内促进植物生长分析表明，用含有 NKZ-259 细胞的高岭土粉末处理的番茄幼苗的根和茎长度分别显著增加了 7.97cm 和 32.77cm，鲜重和干重分别增加了 6.72g 和 1.34g。与对照组相比，植物生长参数增加了近两倍。
优化培养条件使 NKZ-259 细胞分泌的 IAA 增加了近四倍。结果清楚地表明，链霉菌 NKZ-259 具有促进植物生长和 IAA 产生的巨大潜力。此外，基于高岭土的粉末是 NKZ-259 细胞的有效载体，可能对商业应用有用。
