La Guerche Stéphane, Chamont Sophie, Blancard Dominique, Dubourdieu Denis, Darriet Philippe
Faculté d'cenologie, UMR Oenologie-Ampélologie, Université Victor Segalen Bordeaux 2, 351 cours de la libération, 33405, Talence, Cedex, France.
Antonie Van Leeuwenhoek. 2005 Aug;88(2):131-9. doi: 10.1007/s10482-005-3872-4.
One of the consequences of rot on grapes is the development of volatile compounds giving fungal, mouldy or earthy odours. Among these compounds, (-)-geosmin (trans-1,10-dimethyl-trans-9-decalol), a powerful aromatic compound with an earthy smell is a persistent defect in grape juice and wines made with at least partially rotten grapes. A microbiota analysis of rotten grapes containing (-)-geosmin was carried out on sites from four French regions from 1999 to 2002, to clarify the involvement in geosmin appearance of Streptomyces spp. and Penicillium spp., two types of microorganisms present on grape, that are known for their ability to produce geosmin. In earthy grapes, Botrytis cinerea was largely present. Different species of Streptomyces were also isolated, but their pH sensitivity was an extremely limiting parameter for their development on grape juice, grapes or stem, and consequently for their potentiality to generate geosmin in the vineyard. Penicillium expansum, producing geosmin on a model medium, was omnipresent. Penicillium carneum, which is also a geosmin producer, was represented by a single colony during the 4 years of this study. P. expansum alone was able to produce geosmin on a model medium but not on grapes. However, after 7 days' pre-culture of some B. cinerea strains on grape juice, this juice became favourable to geosmin production by P. expansum. We demonstrated the necessary and complementary action of B. cinerea and P. expansum in geosmin production in grape juice and in crushed grape berries.
葡萄腐烂的后果之一是会产生具有真菌、霉味或土腥味的挥发性化合物。在这些化合物中，（-）-土臭素（反式-1,10-二甲基-反式-9-十氢萘醇）是一种具有强烈土腥味的芳香化合物，是用至少部分腐烂葡萄制成的葡萄汁和葡萄酒中持续存在的缺陷。1999年至2002年，对来自法国四个地区的含有（-）-土臭素的腐烂葡萄进行了微生物群落分析，以阐明葡萄上存在的两种已知能产生土臭素的微生物——链霉菌属和青霉属在土臭素产生过程中的作用。在有土腥味的葡萄中，灰葡萄孢大量存在。还分离出了不同种类的链霉菌，但它们对pH的敏感性是其在葡萄汁、葡萄或葡萄茎上生长的一个极其限制的参数，因此也是其在葡萄园产生土臭素潜力的限制参数。在模拟培养基上能产生土臭素的扩展青霉无处不在。在本研究的4年中，同样能产生土臭素的肉色青霉仅由一个菌落代表。单独的扩展青霉能够在模拟培养基上产生土臭素，但不能在葡萄上产生。然而，一些灰葡萄孢菌株在葡萄汁中预培养7天后，这种葡萄汁变得有利于扩展青霉产生土臭素。我们证明了灰葡萄孢和扩展青霉在葡萄汁和破碎葡萄浆果中土臭素产生过程中的必要且互补作用。
