Quantitative determination of the spatial distribution of pure- and mixed-strain immobilized cells in gel beads by immunofluorescence.
A new method was developed to detect and quantify two strains, Lactococcus lactis subsp. lactis biovar. diacetylactis MD and Bifidobacterium longum ATCC 15707, immobilized separately and co-immobilized in gel beads, using specific polyclonal antibodies and confocal laser-scanning microscopy. The establishment of biomass concentration profiles for each strain was measured during colonization of beads using successive pH-controlled batch fermentations. Growth occurred preferentially in 200- and 300-microm peripheral layers of the beads for L. diacetylactis and B. longum, respectively. Repeated-batch cultures with immobilized cells permitted the production of a mixed culture containing a non-competitive strain of bifidobacteria, as a result of immobilized-cell growth and high cell-release activity from the beads. During co-immobilized fermentations, there were no apparent interactions between the strains.
Dairy Research Centre STELA, Pavillon Paul Comtois, Université Laval, Québec, PQ, Canada, G1K 7P4.
Y
Y
Doleyres
I
I
Fliss
C
C
Lacroix
D001644:Bifidobacterium / Q000254:growth & development*; D018533:Biomass; D018914:Cells, Immobilized; D004797:Enzyme-Linked Immunosorbent Assay; D005285:Fermentation; D005455:Fluorescent Antibody Technique; D007778:Lactobacillus / Q000254:growth & development*