Physiological function of exopolysaccharides produced by Lactococcus lactis

The physiological function of EPS produced by Lactococcus lactis was studie d by comparing the tolerance of the non-EPS producing strain L. lactis ssp. cremoris MG1614 and an EPS producing isogenic variant of this strain to se veral anti-microbial factors. There was no difference in the sensitivity of the strains to increased temperatures, freezing or freeze-drying and the a ntibiotics, penicillin and vancomycin. A model system showed that EPS produ ction did not affect the survival of L. lactis during passage through the g astrointestinal tract although the EPS itself was: not degraded during this passage. The presence of cell associated EPS and EPS in suspension resulte d in an increased tolerance to copper and nisin. Furthermore. cell associat ed EPS also protected the bacteria against bacteriophages and the cell wall degrading enzyme lysozyme. However, it has not been possible, so far, to i ncrease EPS production using the presence of copper, nisin, lysozyme or bac teriophages as inducing factors. (C) 2001 Elsevier Science B.V. All rights reserved.