Continuous production of pediocin by immobilized Pediococcus acidilactici PO2 in a packed-bed bioreactor |
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Authors: | H-Y Cho A E Yousef S-T Yang |
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Institution: | (1) Department of Food Science and Technology, The Ohio State University, 2121 Fyffe Road, Vivian Hall, Columbus, Ohio 43210, USA, US |
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Abstract: | A continuous bioreactor packed with a fibrous matrix was set up. Cells of Pediococcus acidilactici PO2 were inoculated and MRS broth was fed gradually until cell growth and immobilization were achieved. Kinetics of fermentation
and production of bacteriocin were investigated at dilution rates ranging from 0.63 day-1 to 1.58 day-1 and at pH values that varied between 4.0 and 5.5. A maximum bacteriocin activity of 6400 AU/ml was detected when the medium
was fermented at dilution rates of at least 1.19 day-1 and the pH controlled at 4.5. The maximum bacteriocin productivity was 1.0×107 AUl-1 day-1 at a dilution rate of 1.58 day-1 and pH 4.5. At this high dilution rate, 1.21 g cells/l medium was produced, 95.9% of the glucose in MRS broth was utilized,
and 15.1 g lactic acid/l accumulated in the bioreactor effluent. The bioreactor was operated continuously for 3 months without
encountering any clogging, degeneration, or contamination problems, indicating good long-term stability of the bioreactor
for bacteriocin production. About 94% of the cells in the bioreactor were immobilized, and the remainder were suspended in
the medium. According to scanning electron microscopic observations, cell immobilization in the fibrous matrix was attained
by natural attachment to fiber surfaces and entrapment in the void volume within the fibrous matrix. In conclusion, conditions
for the optimum continuous production of pediocin were defined; this may facilitate the development of large-scale industrial
processes for production of this bacteriocin.
Received: 25 September 1995/Received revision: 30 November 1995/Accepted: January 1996 |
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