Phosphate solubilization, zinc solubilization, nitrogen fixation and indole-3-acetic acid (IAA) production are plant growth-promoting activities that occur in certain kinds of bacteria. In particular, the rod-shaped proteobacteria isolated from root nodules and rhizospheric soil are considered to be plant growth-promoting. This study aimed to screen and identify plant growth-producing bacteria and included a study of the IAA optimization of the selected isolates. A total of twelve Gram-negative, rod-shaped bacteria were isolated from Leguminosae root nodules and Leguminosae rhizospheric soils. The samples were collected in Udon Thani, Nong Bua Lumphu and Nakhon Phanom provinces, Thailand. Based on the phenotypic characteristics and 16S rRNA gene sequence similarities (99.2-100% similarity), the isolates were characterized as relatives of Rhizobium pusense (2 isolates), Ochrobactrum oryzae (1 isolate), Pseudomonas aeruginosa (1 isolate), Acinetobacter pittii (1 isolate), Klebsiella pneumoniae subsp. rhinoscleromatis (1 isolate), and Pseudomonas geniculata (6 isolates). The isolates were screened for their plant-growth-promoting activities. The results revealed that 8 isolates exhibited phosphate solubilization (10.9 ± 0.00 to 17.0 ± 1.40 Solubilization Index, SI), zinc solubilization (21.5 ± 0.70 to 33.0 ± 1.40 SI) and indole-3-acetic acid production (1.0 ± 0.2 to 113.4±3.5 µg/ml), and 2 isolates showed their nitrogen-fixing activities. The isolates SN1, SN3-3, SN5, PN1-1 and LS1 were selected and optimized for IAA production.
Keywords: proteobacteria; phosphate solubilizing; zinc solubilizing; indole-3-acetic acid
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E-mail: Somboon.T@chula.ac.th
Malisorn, K. undefined. ., Chanchampa, S. undefined. ., Kanchanasin, P. undefined. ., & Tanasupawat*, S. undefined. . (2020). Identification and Plant Growth-Promoting Activities of Proteobacteria Isolated from Root Nodules and Rhizospheric Soils. CURRENT APPLIED SCIENCE AND TECHNOLOGY, 479-493.
