Soil Microorganisms

[title in Japanese]

[in Japanese]

Article type: Article
1995 Volume 45 Pages 1-2
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_1

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Estimation of the number of Gram-negative bacteria based on the number of crystal violet-tolerant bacteria in the environment

Koki Toyota, Makoto Kimura

Article type: Article
1995 Volume 45 Pages 3-7
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_3

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The numbers of crystal violet (CV)-tolerant bacteria were compared with those of gram-negative bacteria based on gram-staining of isolates from soil environments. Although the numbers were very different, a significant positive correlation (r=0.989) was observed between the two groups, suggesting that it was possible to estimate the number of gram-negative bacteria in a sample based on the number of CV-tolerant bacteria. However, such an estimation could not be applied to samples like earthworm guts or earthworm casts, where specific bacteria exclusively predominate.

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Compatibility between host and arbuscular mycorrhizal fungi, and influence of host plant species on the competition among the fungi

Tatsuhiro Ezawa, Shinya Kuwahara, Tomio Yoshida

Article type: Article
1995 Volume 45 Pages 9-19
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_9

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The compatibility between host and arbuscular mycorrhizal fungi and the influence of host species on the competition among the fungi were investigated in a pot experiment. Marigold, soybean and asparagus were inoculated with one (noncompetitive conditions) or three (competitive conditions) species of arbuscular mycorrhizal fungi, Glomus etunicatum (Ge), G. mosseae (Gm) and Gigaspora sp. Cl (Cl), and cultivated in a greenhouse for 77-134 days. The dry weight of the plants, the percentage of infected root length and the number of spores of each fungus were determined, The compatibility was evaluated based on the mycorrhizal growth promotion in host plant and fungal proliferation under non-competitive conditions. The growth of all the plant species was promoted by the inoculation of Ge and Gm, whereas no growth promotion was observed in the plants inoculated with Cl. The most suitable plant species for the proliferation (spread of infection and sporulation) of individual fungus was different among these three fungi. The influence of host plant species on the competition among the three fungi (Ge, Gm and Cl) was evaluated by comparing the spore number of each fungus under competitive conditions and that under non-competitive conditions. In the rhizosphere of marigold, the competitive ability of the three fungi was almost even, while the rhizosphere of soybean and asparagus, only Ge was competitive and became dominant.

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Screening of suppressive soils to Fusarium wilt from Kanto, Tozan and Tokai areas in Japan, and analysis of their suppressiveness

Norihiko Kobayashi, Hajimu Komada

Article type: Article
1995 Volume 45 Pages 21-32
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_21

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Five out of 55 soil samples collected in the Kanto, Tozan and Tokai areas in Japan were suppressive to Fusarium wilt of cucumber caused by Fusarium oxysporum f. sp. cucumerinum, and 8 soils were suppressive to Fusarium wilt of kidney bean caused by F. solani f. sp. phaseoli. There was a close relationship between the disease severity and the soil pH values. Most of the suppressive soils to cucumber Fusarium wilt showed a higher soil pH than the non-suppressive soils. On the other hand, the suppressive soils to kidney bean Fusarium wilt showed lower pHs, and in these acid soils spore germination was inhibited. In the soils in which the pH had been adjusted to various values, the suppressiveness of cucumber Fusarium wilt and kidney bean Fusarium root rot was examined. Cucumber Fusarium wilt was almost completely suppressed at pH 8.0, while kidney bean root rot at pH 4.0.

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Relationship between root length density and decrease in population of Phialophora gregata f. sp. adzukicola

Jun Souma, K. Kobayashi, A. Ogoshi

Article type: Article
1995 Volume 45 Pages 33-39
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_33

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It has been reported that the population of Phialophora gregata f. sp. adzukicola, the pathogen of brown stem rot of adzuki bean, remarkably decreased in soil cultivated with corn. The mechanisms controlling the decrease in the population of the pathogen have not been clarified. We examined the relationship between the root length density and populations of P. gregata f. sp. adzukicola in the soils cultivated with corn, adzuki bean, soybean, and wheat, respectively. The population of the pathogen decreased in the rhizosphere of all the four crops tested. It is suggested that a non-specific rhizosphere effect was involved in the decrease of the population of the pathogen. In furrow soils the populations of the pathogen did not decrease in the adzuki bean plot, unlike in the other three plots. In corn, soybean, and wheat plots, the root length density in the furrow soil was higher than that in the adzuki bean plot. On the basis of these results, it is suggested that the population of P. gregata f. sp. adzukicola in soil decreased when a crop with a large rooting zone and high root length density was cultivated.

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Dynamics of indigenous and inoculated bacterium in soil : A case study of γ-BHC-decomposing Sphingomonas paucimobilis

Keishi Senoo, Masaya Nishiyama

Article type: Article
1995 Volume 45 Pages 41-50
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_41

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Effect of UV-irradiation on plate counts of bacteria from paddy field soil

Pavel A. Shigalevich, Tsutomu Hattori

Article type: Article
1995 Volume 45 Pages 51-54
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_51

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This study was designed to detect the effect of prolonged exposure to solar UV-radiation on the plate counts of heterotrophic bacteria in water-covered paddy field soil. Soil samples were taken from a field exposed to solar radiation when rice plants were young (ca. 3cm high) and a shadowed field when the plants were fully grown. Petri dishes for the respective samples were divided into two parts; before incubation one part was exposed to UV-irradiation (44.5J/m^2) and the other was not exposed (control). Although bacterial counts on control dishes were remarkably lower for the soil exposed to solar radiation than for the shadowed one, the counts on UV-irradiated dishes were similar for both samples. The results suggest that prolonged exposure to solar UV-radiation exerts a selective effect on bacteria in the field.

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Vesicular-arbuscular mycorrhizas in apple orchards in Aomori prefecture, Japan

Tomoyuki Kon

Article type: Article
1995 Volume 45 Pages 55-59
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_55

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Pure isolation and characterization of a new chemoautotrophic nitrite-oxidizing bacterium, Nitrobacter sp. TH21

Tatsuaki Tokuyama, Reiji Takahashi, Yuko Henmi, Miyako Kohga, Kazuhito ...

Article type: Article
1995 Volume 45 Pages 61-65
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_61

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A new nitrite-oxidizing bacterium, strain TH21 was isolated on a 10^4-fold diluted BE-medium agar plate by screening a total of 150 soil samples. The cells of strain TH21 were gram-negative, rod-shaped, 0.5-1.0×1.0-2.0μm in size, chemoautotrophic, obligately aerobic, and motile with a single subpolar flagellum. Cells reproduced by budding which is characteristic of the genus Nitrobacter. The G+C content of the DNA was 61.0 mol%. The optimum concentration of sodium nitrite for the growth of Nitrobacter agilis ATCC 14123 was 3 mM but not 7 mM. Strain TH21 was assigned as belonging to the genus Nitrobacter.

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[title in Japanese]

[in Japanese]

Article type: Article
1995 Volume 45 Pages 67-
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_67

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[title in Japanese]

[in Japanese]

Article type: Article
1995 Volume 45 Pages 68-
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_68_1

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[title in Japanese]

[in Japanese]

Article type: Article
1995 Volume 45 Pages 68-69
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_68_2

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[title in Japanese]

[in Japanese]

Article type: Article
1995 Volume 45 Pages 69-70
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_69

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[title in Japanese]

[in Japanese]

Article type: Article
1995 Volume 45 Pages 70-71
Published: March 01, 1995
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.45.0_70

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