| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1992: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1991: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Sulfur-oxidizing bacteria,collected from a neutralization plant of the abandoned Matuo mine,has been cultured in an enrichment with elemental sulfur.In the culture,we have confirmed protozoa which belongs to Bodo edax without sulfur-oxidizing bacteria and fungus.This study describes interaction between bacteria and protozoa in an enrichment culture.To investigate the interaction,sulfur oxidation experiments are performed under the various conditions.The results obtained are summarized as follows:
(1)The elemantal sulfur oxidaition by the bacteria in pure culture is faster than in enrichment.In the case,the yield factor of sulfur-oxidizing bacteria growth in pure culture is about 3 times as large as that in enrichment culture.
(2)The ratio of protozoa to sulfur-oxidizing bacteria is nearly constant.At pH value above 0.6,protozoa can increase,but decrease at pH value than 0.6.
(3)In pure culture,sulfur-oxidizing bacteria is inhibited at the concentration of Cu^<2+> above lmgdm^<-3> .In enrichiment cultre,the bactreia is in the same as the case of pure culture.Protozoa increases at the concentration of Cu^<2+> ,1,10mgdm^<-3>,but the amount of growth decreases.At 100mgdm^<-3>,protozoa can not increase,and at 1000mgdm^<-3>it can not be confirmed at all after about 200 hours.
(4)In the case of subculture with Cu^<2+>, sulfur-oxidizing bacteria is accompanied with Cu^<2+>-resistant ,but protozoa can not do.
(5)The yield factor of sulfur-oxidizing bacteria growth in enrichment culture depends on protozoa existence.The value in the protozoa-free case is about 7 times as large as when there exists protozoa.
(6)The oxidation rate by the bacteria rises at pH value less than 0.6.This phenomenon may be due to a cycle of nutritive salts through the decomposition of protozoa death cells.
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