Wine Microorganisms

However, in the same grape must, interactions also depend on the strains. LAB growth can be much easier in the wines which are made when certain yeast strains are dominant (Fomachon 1968). Yeasts differences can be attributed to many factors such as the production of varying levels of SO and fatty acids as well as specific proteinaceous molecules and mannoproteins. The last two compounds should act as inhibitors (Comitini et al. 2005) or activators, respectively (Diez et al. 2010). 

In addition yeast cell walls, obtained by separating the soluble yeast extract from the insoluble cell wall after autolysis, detoxify the medium by absorbing the toxic fatty acids. They are added to wine for the promotion of MLF (Lafon-Lafourcade et al. 1983). 

LAB also interact among themselves. Some Pediococcus and Lactobacillus strains were shown to be inhibitors of other lactobacilli and more often of Leuc. mesenteroides and O. oeni also Lact. plantarum seems to be capable of inhibiting O. oeni. Bacteriocin production as well as the presence of sequences of the bacteriocin pin locus were established in inhibitory strains (Navarro et al. 2000 Knoll et al. 2008). In contrast, mutualism was demonstrated between a strain of Pediococcus pentosaceus and one of O. oeni. The high proteolytic activity of the O. oeni released essential amino acids for the P. pentosaceus strain (Fernandez and de Nadra 2006). All these phenomena are very complex involving a huge variety of strains that represent each of the species simultaneously present in the wine. 

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Romano, P, Suzzi, G. (1993) Sulfur dioxide and wine microorganisms. In G.H. Fleet (Ed.), Wine Microbiology and Biotechnology (pp. 373-393). Reading Harwood Academic. 

Granchi, L., Romano, R, Mangani, S., Guerrini, S. Vincenzini, M. (2005). Production of biogenic amines by wine microorganisms. Bull OlV, 78, 595-609. 

Smit, A.Y. (2007). Evaluating the influence of winemaking practices on biogenic amine production by wine microorganisms. Master Thesis. Stellenbosch University. Stellenbosch, South Africa. 

Grapes contain several hydroxycinnamic acids, p-coumaric, caffeic, ferulic and sinapic acids, which exist as free acids and esterified with tartaric acid. Saccha-romyces species can take up free acids to produce the corresponding vinyl phenol catalysed by hydroxycinnamate decarboxylase (phenylacrylic acid decarboxylase Padlp) (Fig 8D.11) (Chatonnet et al. 1992b Chatonnet et al. 1993 Edlin et al. 1995). Vinyl phenols are unstable and highly reactive. Dekkera bruxellensis is one of few wine microorganisms that can further reduce vinyl phenols to highly stable ethyl phenols in wine. Vinyl phenols can also react with anthocyanins to form vinyl derivatives, a reaction that is favoured by fermentation yeast having hydroxycinnamate decarboxylase activity (Morata et al. 2006). 

Wine is a complex mixture consisting of indigenous components and those obtained by chemical and biochemical transformations by wine microorganisms and/or during wine aging. Wine composition varies widely and is influenced by the grape (variety, quality) and by the winemaking conditions. 

VIII. Interactions between Bacteria and Other Wine Microorganisms... 

VIII. INTERACTIONS BETWEEN BACTERIA AND OTHER WINE MICROORGANISMS... 

Romano, P. and Suzzi, G. 1993. Sulphur dioxide and wine microorganisms. In Wine Microbiology and Biotechnology (G.H. Fleet, ed.), pp. 373-393. Harwood Academic Publishers, Switzerland. Ruiz, A., Poblet, M., Mas, A., and Guillamon, J.M. 2000. Identification of acetic acid bacteria by RFLP of PCR-amplified 16s rDNA and 16S-23S rDNA intergenic spacer. Ini. J. Syst. Microbiol. 50, 1981-1987. 

MUlet, V., Lonvaud-Funel, A. (2000). The viable but non-cuturable state of wine microorganisms dnring storage. Letters in Applied Microbiology, 30,136-141. 

Hot water (>82 C/180 F) and steam are ideal sterilants. Both have excellent penetrative properties, are generally noncorrosive, and effective against aU juice and wine microorganisms. For instance, WUker and Dharmadhikari (1997) compared various treatments for sanitizing barrels infected with acetic acid bacteria and noted that the hot water treatment used (85°G/185 F to 88 C/190 F for 20 min) was most effective (Section 11.2.1). However, both hot water/steam may more rapidly degrade gaskets compared with other techniques. 

When a winery considers investment in laboratory equipment, a compound microscope should be a priority. Microscopic capabilities allow winemakers to quickly monitor the progress of alcoholic and malolactic fermentations and to tentatively determine the source of microbiological problems. This chapter oudines basic microscopy as well as techniques to view wine microorganisms. 

Whenever possible, samples for microbiological analysis (50 to 100 mL) should be removed asepticaUy and placed into sterile containers to reduce the potential for secondary contamination due to non-wine microorganisms. Samples can be removed through sampling ports on tanks or by wine thiefs/pipettes. Sampling devices should be sterilized either by flame or 70% v/v ethanol prior to use. If a steriliant is used, the thief or pipette should be rinsed with sterile water before obtaining the sample. 

As with other molecular methods, separation and identification of satellite protein requires a suitably equipped and staffed molecular biology laboratory. However, methods may eventually be reduced to kit form, where most labs will have the capability for rapid identification of wine microorganisms using their satellite information. 

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