Soil Microorganisms

Nitrite Production from Hydroxylamine by Hydroxylamine-cytochrome c reductase in Nitrosomonas europaea

Tatsuaki TOKUYAMA, Shuji SUMIDA

Article type: Article
1988 Volume 31 Pages 1-11
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_1

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An active fraction of hydroxylamine-cytochrome c reductase (NH_2OH-cyt. c reductase) was isolated from N. europaea. The production of nitrite from hydroxylamine by this fraction was subsequently evaluated. The fraction with NH_2OH-cyt. c reductase and nitrite synthetase activities was obtained using DEAE-sepharose column chromatography. The fraction, f13, contains cytochrome and related compounds with a NH_2OH-cyt. c reductase activity. The activity from this fraction was higher than that of fraction F. 6 obtained by DEAE-cellulose column chromatography. The purity of fraction f13 was higher than that of F. 6, and the same enzyme protein was detected in both fractions. The cytochrome in fraction f13 was identified haem c. using the absorption spectrum of pyridine ferrohaemochrome and extracted haem. The f13 fraction was subsequenty divided into three protein fractions by gel filtration over a sephadex G-100 column, affording apl fraction exhibiting activities of both enzymes. Thispl fraction was further divided into five protein fractions using polyacrylamide gel electrophoresis. Activity representative of both enzymes was found in the a3 fraction. SDS-polyacrylamide gel electrophoresis revealed that a3 fraction consists of two subunits with a molecular weight of 175,000. Several studies were carried out on this a3 fraction. The oxidation reaction of hydroxlamine revealed the additive effect of cytochrome c and cytochrome c oxidase. A correlation was noted between the quantity of oxidized hydroxylamine and the quantity of nitrite produced. Even in the presence of excess cytochrome c, the absence of cytochrome c oxidase was related to a 50% reduction in the amount of nitrite formed from hydroxylamine. The reaction ratio of reduced cytochrome c to hydroxylamine was 1:3.

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Factors affecting the germination of spores of Gigaspora margarita

Norihiko KOBAYASHI

Article type: Article
1988 Volume 31 Pages 13-28
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_13

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Effects of factors such as temperature, soil pH and phosphorus concentration, sterilization of spore surface and autoclaving of cultivated soils, the presence or absence of host plants on the germination of spores of Gigaspora margarita were investigated. Moreover, the seasonal variations in spore germination and maturation were monitored. Temperature was found to be the most important factor. Maximum germination of spores of Gigaspora margarita occurred between 25℃ and 35℃. However even at 40℃, 35% of the spores had germinated, but below 15℃ they were unable to germinate. Other factors, including soil pH(4.0-8.0), potassium phosphate concentration (0-250 ppm), sterilization of spore surface and autoclaving of cultivated soils, and the presence or absence of host plants did not affect significantly the germination of spores of Gigaspora margarita. Among agricultural chemicals tested in these experiments, the fungicides, Benlate and Daconil inhibited spore germnation at low concentrtions (0.05ppm, 3.75ppm, respectively). Inhibition of spore germination by insecticides and herbicides was observed at higher concentration than that for the fungicides. Seasonal variations in the percentage of germination of Gigaspora margarita spores collected from same bamboo grass soil at different times during the period 1986-1987 were monitored. In May the spores germinated and penetrated into the host plant when the plant stared to grow. From June to August, the spores remained as germinated spores and they contained a few lipid droplet or were empty. New white spores were found late in September, but they did not germinate due to dormancy. After November, the percentage of spore germination increased month after month.

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Ecology of Bacillus thuringiensis in natural environment

Yoshio AKIBA

Article type: Article
1988 Volume 31 Pages 29-38
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_29

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To analyse the life cycle of the insect pathogen Bacillus thuringiensis in a natural environment, the population dynamics of B. thuringiensis was studied in soils, insect larval body and earth worm body. B. thuringiensis did not grow in natural soils presumably due to the lack of germination factors in soils, competition with the soil microorganisms, acid soil pH. In contrast, B. thuringiensis grew and sporulated in the cadavers of the silkworm larvae and the fall webworm larvae at a low density of competitive microorganisms. B. thuringiensis occurs generally in the spore state in the natural environment and grows in the cadavers of insect larvae.

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Competitive Nodulation Ability of Root-Nodule Bacteria in Soil

Takashi OZAWA

Article type: Article
1988 Volume 31 Pages 39-52
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_39

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Competitive nodulation ability of rhizobia, the ability to compete with other rhizobia for nodulation of host legumes, was analysed on the assumption that the capacity of a rhizobial strain to establish itself in soil and to initiate nodule formation determines the competitive nodulation ability of the strain. The abiotic and biotic environments that may be important in regulating rhizobial populations in soil were briefly described. Attachment of rhizobia to the host plant root surface was considered as a major factor in competition. Some of the nodulation genes of rhizobia were characterized. It was emphasized that the expression of the genes is affected by the soil environment of the rhizobia.

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Ecology and Control of Rhizomania Disease of Sugar Beet

Hideo ABE

Article type: Article
1988 Volume 31 Pages 53-65
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_53

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Rhizomania disease of sugar beet is caused by the beet necrotic yellow vein virus (BNYVV) which is transmitted by the fungus Polymyxa betae. Since the first report of the disease in Italy in the 1950s, the disease has become widely distributed in Hokkaido and several European countries causing important damage to the plants with resultant decrease in sugar yield. A thorough review of past and present research on the causal agent BNYVV, variants of P. betae and virus-vector relationships was presented. Several factors affecting disease development associated with P. betae infection in fields were analysed. For the control of the disease, the importance of forecasting, diagnosis and prevention of dissemination was emphasized. The possibility of cultural and chemical control in nursery beds and main fields and use of tolerant varieties was also discussed.

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Comparison of methods for the detection of Verticillium dahliae in Soil

Toshimasa SHIRAISHI

Article type: Article
1988 Volume 31 Pages 67-69
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_67

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 71-
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_71_1

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 71-72
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_71_2

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 72-73
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_72

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 73-
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_73_1

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 73-74
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_73_2

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 74-75
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_74

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 75-76
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_75

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[title in Japanese]

[in Japanese]

Article type: Article
1988 Volume 31 Pages 76-77
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_76

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[title in Japanese]

Article type: Appendix
1988 Volume 31 Pages 78-
Published: March 01, 1988
Released on J-STAGE: May 31, 2017

DOIhttps://doi.org/10.18946/jssm.31.0_78

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