1999 Fiscal Year Final Research Report Summary
Significance and Functions of Iron-Reduction in Methanogenic Microbial Ecosystem in Wetland Rice Field Soil.
| Project/Area Number |
09680501
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | YAMAGATA UNIVERSITY |
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Principal Investigator |
UEKI Atsuko Facul. Agri., Yamagata Univ., Professor, 農学部, 教授 (60143088)
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| Co-Investigator(Kenkyū-buntansha) |
KASUBUCHI Tatsuaki Facul. Agri., Yamagata Univ., Professor, 農学部, 教授 (00250960)
UEKI Katsuji Facul. Agri., Yamagata Univ., Professor, 農学部, 教授 (10111337)
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| Project Period (FY) |
1997 – 1999
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| Keywords | greenhouse effect / methanogens / wetland rice field / anaerobic bacteria / iron-reducing bacteria / rice plant / ferrous iron / flooded soil |
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| Research Abstract |
Iron-reduction is a key reaction in the process of reduction in flooded rice field soil. In this study, relationship between potential of methane-producing microbial activity and iron reduction in rice field soil was investigated and several isolates of iron-reducing bacteria were isolated from enrichment cultures which has been inoculated with soil of the flooded rice field.
1. Methane-producing microbial activity in soil of a rice field was determined throughout the year. Methane-producing activity increased after flooding of the field and decreased rapidly after mid-season drainage. Fe(II) content in the soil also increased after flooding, indicating the progress of the reduction in the soil. The Fe(II) content in soil changed in parallel with that of potential of methane-producing activity in soil and a significant and high correlation coefficient was obtained between the methane-producing activity and Fe(II) content in soil.
2. Enrichment cultures of iron-reducing bacteria of paddy soil were established with HィイD22ィエD2, acetate, and fumarate as electron donors. The enrichment culture which had been transferred by using HィイD22ィエD2 and fumarate as electron donors also reduced iron with formate, pyruvate, lactate, succinate, malate, ethanol, glutamate, and serine as electron donors as well as HィイD22ィエD2 and fumarate. Thus, it was shown that various compounds should be used as electron donors for iron-reduction in paddy soil.
3. Several strains of iron-reducing bacteria were isolated from the enrichment culture and utilization of electron donors and some other physiological characteristics were determined. These strains were facultatively anaerobic, Gram-negative and motile short-rods and reduced iron by using HィイD22ィエD2, pyruvate and serine as electron donors. Sequences of 16SrRNA gene of these strains were determined and it was shown that these isolates are classified to Proteobacteria γ subdivision and are closely related to the genus Aeromonas.
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