New method for exopolysaccharide determination in culture broth using stirred ultrafiltration cells.
A new method to remove simple carbohydrates from culture broth prior to the quantification of exopolysaccharides (EPS) was developed and validated for the EPS-producing strain, Lactobacillus rhamnosus RW-9595M. This method uses ultrafiltration (UF) in stirred cells followed by polysaccharide detection in the retentate by the phenol-sulfuric acid method. The UF method was compared with a conventional method based on ethanol extraction, dialysis, protein removal by trichloroacetic acid (TCA) and freeze-drying. EPS production during pH-controlled batch fermentations in basal minimum medium, whey permeate (WP). and whey permeate supplemented with yeast extract, minerals and Tween-80 (SWP) was determined by the new UF and conventional methods. EPS recovery by the new method ranged from 83% to 104% for EPS added in the concentration range 40-1,500 mg/l in 0.1 M NaCl solution or culture medium. The UF method was rapid (8 h), accurate and simple, and required only a small sample volume (1-5 ml). A very high maximum EPS production was measured in SWP by both the UF and conventional methods (1,718 and 1,755 mg/l).
Bergmaier
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Dairy Research Centre STELA, Pavilion Paul Comtois, Université Laval, Québec, PQ, Canada.
Lacroix
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Guadalupe Macedo
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Champagne
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D019344:Lactic Acid / Q000378:metabolism; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism*; D007785:Lactose / Q000378:metabolism; D016014:Linear Models; D011135:Polysaccharides, Bacterial / Q000032:analysis / Q000378:metabolism*; D014462:Ultrafiltration / Q000379:methods*
D011135:Polysaccharides, Bacterial; D019344:Lactic Acid; D007785:Lactose