| Project/Area Number |
10650784
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生物・生体工学
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| Research Institution | Osaka University |
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Principal Investigator |
SHIMIZU Hiroshi Department of Biotechnology, Graduate School of Engineering, Osaka University, Associate Professor, 大学院・工学研究科, 助教授 (00226250)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIYAMA Keiji Department of Biotechnology, Graduate School of Engineering, Osaka University, Research Associate, 大学院・工学研究科, 助手 (60294039)
SHIOYA Suteaki Department of Biotechnology, Graduate School of Engineering, Osaka University, Professor, 大学院・工学研究科, 教授 (50026259)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | lactic acid bacteria / yeasts / mixed culture / nisin / cascade controller / bacteriocin / dissolved oxygen concentration / maltose / ラクトース |
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| Research Abstract |
In order to control pH in an antimicrobial peptide (nisin) production process by a lactic acid bacterium (LAB), Lactococcus lactis subsp. lactis (ATCC11454), a novel method was developed, in which neither addition of alkali nor a separation system such as ceramic membrane filter and electrodialyzer was adopted. A mixed culture of L. lactis with Kluyveromyces marxianus, which was isolated from kefir grains, was utilized in the developed system. Interaction between lactate production by L. lactis and its assimilation by K. marxianus was used to control the pH. In order to utilize microbial interaction to maintain high production of nisin, the kinetics of growth and production of lactate, acetate and nisin by L. lactis were investigated. Kinetics of growth and lactic acid consumption of K. marxianus were also investigated. Because pH level in the medium could be controlled by the lactate consumption of K. marxianus and the specific lactate consumption rate of K. marxianus could be controlled by changing the dissolved oxygen (DO) concentration, a cascade pH controller coupled with DO control was newly developed. As a result, pH and lactate were kept at low levels and nisin accumulated in the medium to a high level, compare with other pH control strategies such as processes without pH control and with pH control by addition of alkali.
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