|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1996 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1995 : ¥1,400,000 (Direct Cost : ¥1,400,000)
The present study is concerned with effective production of bioproducts by foam-control bioreactors fitted with a rotating-disk mechanical foam-breaker (MFRD) which utilizes impact action of liquid particles dispersed from the rotating disk by centrifugal force. Firstly, importance of the gas-liquid contact area in aerobic microbial reactions using foamy substrates was pointed out on the basis of the results obtained by shaking cultures with and without the addition of AFs. That is, it was clarified that when the foaming in foamy microbial reactions using bioreactors with gas-sparging was controlled mechanically without the use of AFs a large increase of the gas-liquid contact area could be expected due to foaming. Secondly, for microorganic cell mass production such as S.cerevisiae and E.coli, foaming culture by bubble column bioreactors (BCBs) and aerated agitated-vessel bioreactors (AABs) fitted with MFRDs was carried out. The consumption of substrates and the growth were confirmed
to proceed very smoothly without incurring defects experienced under foam control by the addition of AFs. Comparison of the productivity and the power input efficiency between two cultivation systems when the foaming was controlled by the MFRD and AFs also demonstrated the superiority of mechanically controlled foaming system, i.e., foaming culture. Furthermore, the AAB with the MFRD was applied to the production process of a metabolite, acetic acid, by A.aceti. The MFRD was proved to be useful in controlling foaming in acetic acid fermentation when foamy substrates were used. It was also clarified that in the foaming culture by use of this type of bioreactor the yield of acetic acid was high and the time required for fermentation could be shortened remarkably compared with the cultivation system added the AF.
A collection of the data obtained in the present study is anticipated to contribute as a significant and practical guide-line for operation and designing of foaming culture suited for effective and economic production of bioproducts. Less