Interactions between milk proteins and exopolysaccharides produced by Lactococcus lactis observed by scanning electron microscopy

J Dairy Sci. 2008 Jul;91(7):2583-90. doi: 10.3168/jds.2007-0876.

Abstract

The interactions between exopolysaccharides produced by Lactococcus lactis ssp. cremoris JFR1 and dairy proteins (caseins and whey proteins) in fermented media (milk permeate and buttermilk) were observed using scanning electron microscopy. An immobilization technique by crosslinking was employed to bind the protein to the observation surface, so that a washing step could be performed to remove noninteracting material. The use of this novel technique allowed us, for the first time, to confirm that the exopolysaccharide molecules interact with dairy proteins. Exopolysaccharides appear as filament strands attached to the protein aggregates and to the bacterial cells. This new sample preparation technique proved to be very valuable for observing molecular interactions in fermented media.

MeSH terms

  • Animals
  • Caseins / chemistry*
  • Caseins / ultrastructure
  • Cultured Milk Products / chemistry
  • Cultured Milk Products / microbiology
  • Fermentation
  • Lactococcus lactis / metabolism*
  • Microscopy, Electron, Scanning / methods*
  • Milk / chemistry
  • Milk / microbiology
  • Milk Proteins / chemistry*
  • Milk Proteins / ultrastructure
  • Polysaccharides, Bacterial / biosynthesis
  • Polysaccharides, Bacterial / chemistry*
  • Polysaccharides, Bacterial / ultrastructure
  • Whey Proteins

Substances

  • Caseins
  • Milk Proteins
  • Polysaccharides, Bacterial
  • Whey Proteins