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Application of Cross-Flow Filtration for High Density Cultivation and Regulation of trp Promoter

  • Takeshi Kobayashi
Conference paper

Abstract

A new fermentation system with continuous separation by cross-flow filtration using a ceramic filter was developed. By applying this system, high concentration cultivation of lactic acid bacteria and regulation of trp promoter for induction of a foreign gene by adjusting tryptophan concentration in a medium were carried out.

Streptococcus cremoris, Lactobacillus casei and Bifidobacterium longum were grown in the new fermentor up to high concentrations of 81, 49 and 54 g dry cell weight per liter, respectively. The cell productivities achieved by the fermentation system were 5 to 15 times as high as that of each corresponding conventional batch cultivation.

Escherichia coli harboring the recombinant plasmid containing β-galactosidase gene fused to trp promoter was cultivated in the fermentor with cross-flow filtration. In the initial stage of the cultivation, tryptophan concentration in a medium was kept at 170 µg ml−1. The cross-flow filtration was started when optical density of cells at 570 nm became 10. Trytophan concentration dropped to low level within 30 min and an efficient expression of β-galactosidase gene was started. By this two stage cultivation, very high cell mass was achieved (60 g dry cell weight per liter) and amount of produced β-galactosidase was about 10% of total cellular protein.

Keywords

Lactic Acid Bacterium Recombinant Plasmid Foreign Gene Total Cellular Protein Fermentation System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • Takeshi Kobayashi
    • 1
  1. 1.Nagoya UniversityNagoyaJapan

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