Phosphate solubilization potential and stress tolerance of rhizobacteria from rice soil in Northern Thailand |
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Authors: | Mathurot Chaiharn Saisamorn Lumyong |
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Institution: | (1) Department of Biotechnology, Graduated School, Chiang Mai University, Chiang Mai, Thailand;(2) Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand |
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Abstract: | Plant growth-promoting rhizobacteria (PGPR) are known to influence plant growth by various direct or indirect mechanisms.
A total of 216 phosphate-solubilizing bacterial isolates were isolated from different rice rhizospheric soil in Northern Thailand.
These isolate were screened in vitro for their plant growth-promoting activities such as solubilization of inorganic phosphate,
ammonia (NH3), catalase and cell wall-degrading enzyme activity. It was found that 100% solubilized inorganic phosphate, 77.77% produced
NH3 and most of the isolates were positive for catalase. In addition, some strains also produced cell wall-degrading enzymes
such as protease (7%), chitinase (1%), cellulase (3%) and β-glucanase (3%), as evidenced by phenotypic biochemical test and quantitative assay using spectrophotometry. The isolates
could exhibit more than two or three plant growth-promoting (PGP) traits, which may promote plant growth directly or indirectly
or synergistically. Part of this study focused on the effect of NaCl, temperature, and pH on a specific the bacterial isolate
Acinetobacter CR 1.8. Strain CR 1.8 was able to grow on up to 25% NaCl, between 25 and 55°C, and at pH 5–9. Maximum solubilization of tricalcium
phosphate and aluminium phosphate was obtained at neutral pH, and 37°C. Strain CR 1.8 had protease activity but no cellulase,
β-glucanase and cellulase activities. |
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Keywords: | Plant growth-promoting rhizobacteria Phosphate-solubilizing bacteria Rice (Oryza sativa) Cell wall-degrading enzyme |
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