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15(2)2025 (IN PRESS)

Optimization of indole-3-acetic acid production by Bacillus subtilis strain IA3


Author - Affiliation:
Tuan Ngoc Nguyen - Ton Duc Thang University, Ho Chi Minh City , Vietnam
Linh Huynh Yen Luu - Ton Duc Thang University, Ho Chi Minh City , Vietnam
Corresponding author: Tuan Ngoc Nguyen - nguyenngoctuan@tdtu.edu.vn
Submitted: 18-03-2025
Accepted: 02-05-2025
Published: 07-05-2025

Abstract
Indole-3-acetic acid (IAA) is a crucial plant growth promoting hormone produced as secondary metabolite by various microorganisms. The present study aims to isolate and screen IAA-producing endospore-forming bacteria from soil samples collected in Vietnam. A total of ten bacteria were isolated and shown the ability to produce IAA with strain IA3 exhibiting the highest production. Strain IA3 was identified as Bacillus subtilis based on the 16S rRNA sequencing and subsequently used to optimize conditions for IAA production. To maximize IAA yield, key factors influencing production were analyzed using Box-Behnken design. The optimized conditions led to a maximum IAA production of 47.67 ± 0.78 g/mL under the following condition: 15.65 g/L molasses, 1.06 g/L (NH4)2SO4 and 0.52 g/L tryptophan. Therefore, Bacillus subtilis IA3 has potential application for stimulating and enhancing plant growth or crop production.

Keywords
Bacillus; Indole-3-acetic acid; optimization

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DOI: https://doi.org/10.46223/HCMCOUJS.tech.en.15.2.4232.2025
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