Applied Microbiology and Biotechnology

, Volume 57, Issue 5–6, pp 626–630

Continuous lactic acid fermentation using a plastic composite support biofilm reactor

  •  J. Cotton
  •  A. Pometto
  •  J. Gvozdenovic-Jeremic
Original Paper
  • 234 Downloads

Abstract.

An immobilized-cell biofilm reactor was used for the continuous production of lactic acid by Lactobacillus casei subsp. rhamnosus (ATCC 11443). At Iowa State University, a unique plastic composite support (PCS) that stimulates biofilm formation has been developed. The optimized PCS blend for Lactobacillus contains 50% (wt/wt) agricultural products [35% (wt/wt) ground soy hulls, 5% (wt/wt) soy flour, 5% (wt/wt) yeast extract, 5% (wt/wt) dried bovine albumin, and mineral salts] and 50% (wt/wt) polypropylene (PP) produced by high-temperature extrusion. The PCS tubes have a wall thickness of 3.5 mm, outer diameter of 10.5 mm, and were cut into 10-cm lengths. Six PCS tubes, three rows of two parallel tubes, were bound in a grid fashion to the agitator shaft of a 1.2-l vessel for a New Brunswick Bioflo 3000 fermentor. PCS stimulates biofilm formation, supplies nutrients to attached and suspended cells, and increases lactic acid production. Biofilm thickness on the PCS tubes was controlled by the agitation speed. The PCS biofilm reactor and PP control reactor achieved optimal average production rates of 9.0 and 5.8 g l–1 h–1, respectively, at 0.4 h–1 dilution rate and 125-rpm agitation with yields of approximately 70%.

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  •  J. Cotton
    • 1
  •  A. Pometto
    • 1
  •  J. Gvozdenovic-Jeremic
    • 1
  1. 1.Department of Food Science and Human Nutrition, Center for Crops Utilization Research, 2312 Food Sciences Building, Iowa State University, Ames, IA 50011, USA

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