| Project/Area Number |
14360042
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plant nutrition/Soil science
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| Research Institution | National Agricultural Research Organization |
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Principal Investigator |
HASHIMOTO Tomoyoshi National Agricultural Research Organization, National Agricultural Research Center for Kyushu Okinawa Region, Department of Agro-Environmental Research, Head of Laboratory, 九州沖縄農業研究センター環境資源研究部, 室長 (90343946)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANE Tsuyosi National Agricultural Research Organization, Researcher, 研究員 (80414853)
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| Project Period (FY) |
2002 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥12,600,000 (Direct Cost: ¥12,600,000)
Fiscal Year 2005: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2004: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2003: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2002: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Keywords | Denitrification / Oligotrophic denitrifying bacteria / Slurry / Nitrogen dynamics / Subsurface soil / N_2O / International research cooperation / South Korea |
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| Research Abstract |
This is the first investigation to show that oligotrophic denitrifying bacteria are dominant denitrifying bacteria in subsurface upland soil. We examined the vertical distribution of denitrifying bacterial populations in upland soil using two kinds of enumeration media. The number of denitrifying bacteria, enumerated in subsurface soil layers by a 100-fold diluted nutrient broth (DNB) medium with NO_<3^->, was two to three orders of magnitude greater than those enumerated by a conventional nutrient broth medium with NO_<3^-> suggesting the dominance of oligotrophic denitrifying bacteria. Seventy-four percent of the total denitrifying bacterial isolates were DNB organisms of the oligotrophic type, which did not show appreciable growth on conventional nutrient broth medium. The isolates were heterogeneous and were categorized as alpha (35 strains) and beta (19 strains) subdivisions of proteobacteria and high G+C gram-positive bacteria (7 strains) by 16S rRNA gene sequence analysis (AB118811-AB118817,AB162052-AB162105). The 35 alpha-subdivision of proteobacterial isolates were of oligotrophic type and widely distributed from the surface to subsurface soil layers. Phylogenetic analysis indicated that some isolates belonged to groups with few or no cultivated representatives and that one isolate may be a member of a new genus. This isolation procedure using a diluted media is valuable in detecting diverse and novel denitrifying bacteria in the subsurface soil.
We held International symposium on identification and use of microbial resources for sustainable agriculture on July 28 2004 at Kumamoto, Japan (See the URL http://konarc.naro.affrc.go.jp/photo/symp2004/repo/index-e.htm).
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