Soil Microorganisms
Online ISSN : 2189-6518
Print ISSN : 0912-2184
ISSN-L : 0912-2184
Volume 56, Issue 1
Displaying 1-9 of 9 articles from this issue
  • M. Hyakumachi
    Article type: Article
    2002 Volume 56 Issue 1 Pages 1-
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
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  • Miho Iduhara, Masao Sakai, Shigeki Takaki, Kazuhira Yokoyama, Takuya M ...
    Article type: Article
    2002 Volume 56 Issue 1 Pages 3-10
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
    A biomarker, gfp gene, was introduced into a strain of Ralstonia solanacearum isolated from tomato to investigate the fate of this strain in soil. Tn5-mutants of the strain SL8 were virulent against tomatoes. The behavior of these gfp-fused mutants was similar to that of the wild type strain both in the culture medium and in soil. In the case of the gfp-fused mutants in which the production of extracellular polysaccharides (EPS) was impaired or absent (EPS-), the fluorescence of GFP was useful to discriminate between the inoculated strains from other indigenous bacteria in soil. In conclusion, the biomarker GFP allowed the count of both wild type strains, one which produced large amounts of EPS and the other PC-type mutants in terms of EPS. Subsequently, the gfp-fused mutants of Ralstonia solanacearum enabled to analyze the factors that induce phenotypic conversion from wild type strains under environmental conditions.
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  • Miho Iduhara, Shigeki Takaki, Kazuhira Yokoyama, Takuya Marumoto
    Article type: Article
    2002 Volume 56 Issue 1 Pages 11-22
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
    To suppress bacterial wilt of tomato caused by Ralstonia solanacearum with soil administration, soil conditions that influence the production of extracellular polysaccharides (EPS) in R. solanacearum were surveyed, and the prevention of this disease by strains that do not produce EPS (EPS^- strains) was investigated. The culture conditions, using either liquid medium or sterilized soil were investigated to induce the phenotype conversion (PC) in relation to the reduction or loss of EPS production in R. solanacearum. EPS^- colonies were frequently detected under unfavorable culture conditions, such the use of a rather alkaline medium (pH8 and pH8.5), higher temperature (37℃) or still culture rather than shaking culture. The culture conditions under which the EPS^- colonies were detected with a high frequency varied depending on the strains tested. In the case of culture conditions of the bacterium using either sterilized or non-sterilized soil, EPS^- colonies were also observed with a high frequency in all the cases, including, acidic soil, higher temperature, and soil moisture exceeding the maximum water holding capacity. Disease severity was evaluated after the EPS-producing strains were inoculated either alone or simultaneously with EPS-non-producing strains by mixing into soil where subsequently tomato was planted. When EPS-producing strains and EPS-non-producing strains were simultaneously inoculated, the damage was less serious than in the case of inoculation with EPS-producing strains alone. When the ratio of EPS-non-producing cells to EPS-producing cells increased, the effect on disease suppression was more pronounced. If the phenotype conversion of R. solanacearum living in soil could be induced with a high frequency by soil administration, bacterial wilt disease may be effectively suppressed.
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  • Kazunari Yokoyama, Hirofumi Shinoyama, Takaaki Fujii
    Article type: Article
    2002 Volume 56 Issue 1 Pages 23-29
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
    Structural shifts in soil bacterial communities that occur in response to the addition of catechol to soil were investigated in order to characterize the soils based on response of indigenous bacterial communities to chemical stress. Bacterial numbers in the soils after treatment with catechol (at concentrations of 0.5, 2.0, 5.0, or 10.0 mg/g soil) were determined by the plate count method. Randomly selected isolates were subjected to cluster analysis (UPGMA) on the basis of the utilization pattern of 61 carbon sources (BIOLOG), and the diversity index was calculated using the sum of the distances between each cluster. Bacterial populations and diversity were lower at higher catechol concentrations and increased by the addition of glucose at the concentration of 5.0 mg/g soil. Furthermore, the values of these parameters were lower in the catechol- than in the glucose-treated soils when compared at the same concentration (5.0 mg/g soil), suggesting that catechol exerted a greater selective effect on soil bacterial communities tested than glucose. Principal component analysis of all the bacterial isolates based on the utilization pattern of 31 carbon sources revealed differences among the three test soils in the treatment with catechol and glucose in terms of degree of changes in the isolate composition. These findings suggested that this technique could be useful for the characterization and comparison of the variability of the response of soil bacterial communities to chemical stress. It is recommended that, for the selection of soils used in the test to evaluate the effect of chemicals on the soil microflora, not only physicochemical properties of soils for testing the chemicals but also the variability of the soil microbial communities should be taken into account.
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  • Satoshi Taba, Atsushi Ooshiro, Kazuko Takaesu, Tetsuya Takushi
    Article type: Article
    2002 Volume 56 Issue 1 Pages 31-36
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
    In November 1999, wilt was found on basil in Okinawa prefecture, Japan. The infected plants showed various symptoms including wilt, leaf chlorosis, stem necrosis and partial or total defoliation. Fusarium oxysporum Schlechtendahl: Fries. was consistently isolated from the stem of the diseased plants. Based on the pathogenicity test applied to 17 plant species belonging to 5 families by the root dipping method with a conidial suspension (3×10^5 conidia per milliliter), wilt and defoliation were observed only on basil. F. oxysporum was exclusively recovered from the inoculated plants. Based on these results, the fungus isolated from a dead stem was found to be the pathogen of this disease and was identified as Fusarium oxysporum Schlechtendahl: Fries f. sp. basilicum Dzidzariya. This is the first report of Fusarium Wilt and Crown Rot of basil in Japan.
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  • Kanji Nakamura, Katsutoshi Shibuya, Kazuo Okamura
    Article type: Article
    2002 Volume 56 Issue 1 Pages 37-44
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
  • Shinjiro Kanazawa
    Article type: Article
    2002 Volume 56 Issue 1 Pages 45-54
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
  • [in Japanese]
    Article type: Article
    2002 Volume 56 Issue 1 Pages 55-56
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese]
    Article type: Article
    2002 Volume 56 Issue 1 Pages 57-
    Published: April 01, 2002
    Released on J-STAGE: May 31, 2017
    JOURNAL FREE ACCESS
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