Microbial interactions

Abstract

Wine fermentation is characterized by complex chemical and microbial interactions. Competition for fermentable sugars and growth factors in the presence of SO2, followed by more anaerobic conditions and increasing levels of ethanol, provides an ideal background for fierce interactions among yeast, malolactic bacteria, and between yeast and malolactic bacteria. Lactic acid, acetic acid, hexanoic, octanoic and decanoic acids produced by yeast, SO2, H2O2, diacetyl, acetoin, antimicrobial peptides (e.g. bacteriocins produced by malolactic bacteria and killer toxins produced by yeast) and other yet unidentified low-molecular-mass signalling molecules, at various ratios, play a role in the regulation of microbial interactions. Little is known about the effect of mycelial fungi on yeast and malolactic bacteria. Mannoprotein and β-glucans produced by Botrytis cinerea inhibit the growth of Saccharomyces cerevisiae. Unidentified antibacterial cationic proteins produced by S. cerevisiae inhibit the growth of malolactic bacteria. Filamentous fungi may stimulate the growth of S. cerevisiae. © 2009 Springer-Verlag Berlin Heidelberg. All rights reserved.