Affiliation:
1. Department of Food and Microbial Technology1 and
2. Department of Applied Plant Sciences,2 KULeuven, B-3001 Heverlee, Belgium
Abstract
ABSTRACT
Pediococcus damnosus
can coflocculate with
Saccharomyces cerevisiae
and cause beer acidification that may or may not be desired. Similar coflocculations occur with other yeasts except for
Schizosaccharomyces pombe
which has galactose-rich cell walls. We compared coflocculation rates of
S. pombe
wild-type species TP4-1D, having a mannose-to-galactose ratio (Man:Gal) of 5 to 6 in the cell wall, with its glycosylation mutants
gms1-1
(Man:Gal = 5:1) and
gms1
Δ (Man:Gal = 1:0). These mutants coflocculated at a much higher level (30 to 45%) than that of the wild type (5%). Coflocculation of the mutants was inhibited by exogenous mannose but not by galactose
.
The
S. cerevisiae mnn2
mutant, with a mannan content similar to that of
gms1
Δ, also showed high coflocculation (35%) and was sensitive to mannose inhibition. Coflocculation of
P. damnosus
and
gms1
Δ (or
mnn2
) also could be inhibited by
gms1
Δ mannan (with unbranched α-1,6-linked mannose residues), concanavalin A (mannose and glucose specific), or NPA lectin (specific for α-1,6-linked mannosyl units). Protease treatment of the bacterial cells completely abolished coflocculation. From these results we conclude that mannose residues on the cell surface of
S. pombe
serve as receptors for a
P. damnosus
lectin but that these receptors are shielded by galactose residues in wild-type strains. Such interactions are important in the production of Belgian acid types of beers in which mixed cultures are used to improve flavor.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
14 articles.
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