TITLE:
Studies on Two Exoenzymes Which Lyse Wine-Spoiling Bacteria
AUTHORS:
Patrick Sebastian, Harald Claus, Helmut König
KEYWORDS:
Streptomyces albidoflavus, Lactobacillus brevis, Wine Spoilage, Stuck Fermentations, Cell Wall, Muramidase, Protease, S-Layer
JOURNAL NAME:
Advances in Microbiology,
Vol.4 No.9,
July
24,
2014
ABSTRACT: Microorganisms play an
important role in the conversion of grape juice into wine. Different species of
yeast are mainly responsible for the production of ethanol. Lactic acid
bacteria also occur regularly in must or wine. They are mostly undesirable due
to their capacity to produce wine-spoiling compounds. Especially strains of Lactobacillus brevis are able to produce
biogenic amines as well as precursors of ethyl carbamate and different
off-flavours (N-heterocycles, volatile phenols). By excessive formation of
acetic acid some lactobacilli may even induce slow/stuck grape juice
fermentations. In conventional winemaking, additions of sulphite or lysozyme
are used to inhibit the growth of spoilage microorganisms. There is a strong
interest in finding alternatives, because of the reduced activity of lysozyme
in the wine milieu, a limited growth-inhibiting activity against lactic acid
bacteria, and some health risks described regarding the application of
sulphite. We found that a culture supernatant of Streptomyces albidoflavus B 578 lysed all bacteria previously
isolated from must and wine samples (Acetobacter sp., Lactobacillus sp., Leuconostoc sp., Oenococcus oeni, Pediococcus sp., Staphylococcus sp.) including 35 strains of L. brevis. Two bacteriolytic exoenzymes were isolated and
characterized from the streptomycete: a muramidase (24 kDa) and a protease (17
kDa). Both hydrolyzed cell wall components of L. brevis (peptidoglycan, S-layer proteins) and were active under
wine-relevant conditions.