Presentation Information
[P03-302]Effect of phosphate solubilizing bacterium strain NKPB72 on soybean growth in phosphate absorption soils
○Kazuya Yokoo1, Akane Mizusawa1, Satoshi Murata1, Akiko Hanada2, Tomoaki Kasuga2, Tsuyoshi Aketo2, Yohei Nishikawa3,4, Haruko Takeyama4,5,6, Atsushi Arakaki1, Tsuyoshi Tanaka1 (1. Graduate School of Engineering, Tokyo University of Agriculture and Technology (Japan), 2. Central Research Laboratory, Taiheiyo Cement Corporation (Japan), 3. Biomanufacturing and Process Research Center, National Institute of Advanced Industrial Science and Technology (AIST) (Japan), 4. Research Organization for Nano and Life Innovation, Waseda University (Japan), 5. Department of Life Science and Medical Bioscience, Waseda University (Japan), 6. Institute for Advanced Research of Biosystem Dynamics, Waseda University (Japan))
Keywords:
Biofertilizer,Phosphate-solubilizing bacteria,Soybean
[Purpose]
Phosphorus is an essential nutrient for plant growth; however, global phosphate rock reserves are being rapidly depleted. In Japan, approximately 30% of agricultural land consists of Andisols—highly phosphorus-adsorptive soils—making phosphorus availability a critical challenge. To address this, we investigated the phosphate solubilizing bacterium, Bacillus sp. NKPB72, isolated from high-yield soybean fields. This study characterizes the functions of NKPB72 based on genome analysis and evaluates its potential to improve phosphorus availability and promote soybean growth in Andisol.
[Method]
Bacillus sp. NKPB72, a phosphate-solubilizing bacterium isolated from a soybean cultivation field, was used in this study. Genome completeness was evaluated using BUSCO, and plant growth-promoting genes were searched using PLaBAse. A comparative analysis of NKPB72 genes with those of 6 Bacillus strains reported to have plant growth-promoting effects was conducted to extract genes specific to NKPB72. Soils with different phosphate absorption coefficients were prepared by mixing vermiculite and Andisol, and a soybean pot cultivation experiment was conducted. After five weeks, the dry weight of the soybean plants was measured.
[Results]
Analysis using PLaBAse detected 486 genes involved in plant growth promotion. Comparative gene analysis with 6 Bacillus strains reported to have plant growth-promoting effects revealed 19 genes common to NKPB72 and the 6 strains. Furthermore, 14 genes were considered specific to NKPB72. A pot cultivation experiment with soybeans was then conducted in soil supplemented with strain NKPB72. In soil with a phosphate absorption coefficient of 1400, the dry weight of cultivated soybean plants increased by approximately 60% compared to soybeans without NKPB72 supplementation. No significant changes in dry weight were observed in soils with phosphate absorption coefficients below 1000 or above 1800.
[Consideration]
Nineteen plant growth-promoting genes common to 6 Bacillus strains and NKPB72 were identified, along with 14 genes specific to NKPB72. Further analysis of these strain-specific genes may provide clues to the phenotype and environmental adaptations of NKPB72, supporting its application as a biofertilizer.In pot experiments supplemented with NKPB72, soybean dry weight increased significantly only under conditions with 50% Andisol content, while no significant changes were observed under other conditions. The lack of a growth-promoting effect under other conditions was likely due to inhibition of NKPB72 activity caused by bacterial adsorption onto soil particles and phosphorus adsorption in the soil.
[Conclusion]
NKPB72 is a potentially effective biofertilizer for promoting soybean growth in phosphate-adsorbing soils.
[Acknowledgement]
This work was supported by Cabinet Office, Government of Japan, Moonshot R&D Program for Agriculture, Forestry and Fisheries.
Phosphorus is an essential nutrient for plant growth; however, global phosphate rock reserves are being rapidly depleted. In Japan, approximately 30% of agricultural land consists of Andisols—highly phosphorus-adsorptive soils—making phosphorus availability a critical challenge. To address this, we investigated the phosphate solubilizing bacterium, Bacillus sp. NKPB72, isolated from high-yield soybean fields. This study characterizes the functions of NKPB72 based on genome analysis and evaluates its potential to improve phosphorus availability and promote soybean growth in Andisol.
[Method]
Bacillus sp. NKPB72, a phosphate-solubilizing bacterium isolated from a soybean cultivation field, was used in this study. Genome completeness was evaluated using BUSCO, and plant growth-promoting genes were searched using PLaBAse. A comparative analysis of NKPB72 genes with those of 6 Bacillus strains reported to have plant growth-promoting effects was conducted to extract genes specific to NKPB72. Soils with different phosphate absorption coefficients were prepared by mixing vermiculite and Andisol, and a soybean pot cultivation experiment was conducted. After five weeks, the dry weight of the soybean plants was measured.
[Results]
Analysis using PLaBAse detected 486 genes involved in plant growth promotion. Comparative gene analysis with 6 Bacillus strains reported to have plant growth-promoting effects revealed 19 genes common to NKPB72 and the 6 strains. Furthermore, 14 genes were considered specific to NKPB72. A pot cultivation experiment with soybeans was then conducted in soil supplemented with strain NKPB72. In soil with a phosphate absorption coefficient of 1400, the dry weight of cultivated soybean plants increased by approximately 60% compared to soybeans without NKPB72 supplementation. No significant changes in dry weight were observed in soils with phosphate absorption coefficients below 1000 or above 1800.
[Consideration]
Nineteen plant growth-promoting genes common to 6 Bacillus strains and NKPB72 were identified, along with 14 genes specific to NKPB72. Further analysis of these strain-specific genes may provide clues to the phenotype and environmental adaptations of NKPB72, supporting its application as a biofertilizer.In pot experiments supplemented with NKPB72, soybean dry weight increased significantly only under conditions with 50% Andisol content, while no significant changes were observed under other conditions. The lack of a growth-promoting effect under other conditions was likely due to inhibition of NKPB72 activity caused by bacterial adsorption onto soil particles and phosphorus adsorption in the soil.
[Conclusion]
NKPB72 is a potentially effective biofertilizer for promoting soybean growth in phosphate-adsorbing soils.
[Acknowledgement]
This work was supported by Cabinet Office, Government of Japan, Moonshot R&D Program for Agriculture, Forestry and Fisheries.
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