Affordable Access

Publisher Website

Porosity ofLactococcus lactissubsp.lactisLD61 colonies immobilised in model cheese

Authors
Journal
International Journal of Food Microbiology
0168-1605
Publisher
Elsevier
Publication Date
Volume
163
Identifiers
DOI: 10.1016/j.ijfoodmicro.2013.02.014
Keywords
  • Bacterial Colonies
  • Lactoccocus Lactis
  • Cheese
  • Confocal Microscopy
  • Diffusion
Disciplines
  • Biology

Abstract

Abstract During cheese ripening, micro-organisms grow as immobilised colonies, metabolising substrates present in the matrix which generate products triggered by enzymatic reactions. Local limitation rates of diffusion, either in the matrix or within the bacterial colonies, can be responsible for modulation in the metabolic and enzymatic activities of micro-organisms during ripening. How bacterial colonies immobilised in cheese are porous to these diffusing solutes has never been explored. The objective of this study was to determine if fluorescent dextrans of different sizes (4.4, 70 and 155kDa) are able to penetrate through colonies of Lactococcus lactis LD61 immobilised in solid media, either agar or model cheese. Confocal microscopic observations showed that lactococcus colonies immobilised in these two media were porous to dextrans from 4kDa to 155kDa. However, the rate of diffusion of the solutes was faster inside the colonies immobilised in ultrafiltered-cheese than in agar when large dextrans were considered (≥70kDa). The colonial shape of the lactococcus strain was also shown to be lenticular in agar and spherical in the model cheese, indicating that the physical pressure exerted on the colony by the surrounding casein network was probably isotropous in the UF-cheese but not in agar. In both cases, the fact that lactococcus colonies immobilised in solid media are porous to large dextran solutes suggests that substrates or enzymes are likely also to be able to migrate inside the colonies during cheese ripening.

There are no comments yet on this publication. Be the first to share your thoughts.

Statistics

Seen <100 times
0 Comments

More articles like this

An ecological study of lytic bacteriophages ofLact...

on International Dairy Journal Jan 01, 1994

Involvement of a Prophage in the Lysis ofLactococc...

on International Dairy Journal Jan 01, 1998

The influence of phage-assisted lysis ofLactococcu...

on International Dairy Journal Jan 01, 1995

Impact of ropy and capsular exopolysaccharide-prod...

on International Dairy Journal Jan 01, 2005
More articles like this..