| Project/Area Number |
60550683
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
発酵工学
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
NAGAI SHIRO HIROSHIMA UNIV., FAC. OF ENGINEERING, PROFESSOR, 工学部, 教授 (70013307)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIO NAOMICHI HIROSHIMA UNIV., FAC. OF ENGINEERING, ASSOCIATE PROFESSOR, 工学部, 助教授 (30034383)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Vitamin B-12 Production / Propionibacterium sp / Photosynthetic bacterium / Dialysis Culture / Removal of Lower Fatty Acids / 低級脂肪酸除去 / 相利共生透析培養 / B-12高濃度化 |
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| Research Abstract |
Industrial scale production of vitamin B-12 is usually carried out by extracting it from the cells of Propionibacterium spp. anaerobicaaly grown on sugar-complex medium. During growth, bacteria ferment glucose discharoing acetic and propionic acids which severely inhibit the microbial growth. Therefore, it is necessary to avoid the inhibitory effects on the growth by constructing a novel bioreactor for B-12 production.
In this work, a symbiosis culture system was developed by using a dialysis membrane in which the acids produced by P. shermanii can be used by a photosynthetic bacterium, Rhodopseudomonas sphaeroides S. The results obtained were summarized as follows:
1. A mode of inhibition kinetics by the acids on the growth of P. shermanii demonstrated that low cell productivity was depended on lowering both of the specific growth rate and growth yield by propionic acid.
2. Photopigments and vitamin B-12 formation of Rhodopseudomonas gelatinosa were enhanced by a sudden change of the culture condition from aerobic(redox potential, ORP>+110 mV) to microaerobic condition(ORP= 0 to -200 mV).
3. A symbiosis culture of P. shermanii and R. sphaeroides was carried out in a dialysis membrane reactor(cellulose nitrate, permeability coefficient: 0.48 for glucose, 0.55 for propionate and 0.82 cm/h for acetate) where the acids were preferentially consumed by R. sphaeroides. In this system, P. shermanii was growing anaerobically in a gluccse-limited chemostat culture while R. sphaeroides was growing aerobically(DO=2-3 ppm) utilizing the produced acids permeated through the membrane. As the results, the productivities of cell mass and vitamin B-12 by P. shermanii could increase 3 and 2 times, respectively, compared with those of a monoculture of P. shermanii suggesting that a proposed dialysis culture associated with symbiosis might be a useful means to increase B-12 productivity.
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