Indole-3-acetic acid production by Streptomyces fradiae NKZ-259 and its formulation to enhance plant growth.

ABSTRACT: BACKGROUND: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. RESULTS:The maximum IAA yield achieved using optimal conditions was 82.363??g/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. CONCLUSION: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.

SUBMITTER: Myo EM 

PROVIDER: S-EPMC6615096 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature