Kloeckera apiculata Hanseniaspora uvarum

Both the asexual yeast Kloeckera and its perfect counterpart, Hanseniaspora, represent the dominant native species present on grapes at harvest. Historically, their activity was thought to be restricted to prefermentation and early stages of alcoholic fermentation. Depending on temperature, Saccharomyces populations became quickly established and produced sufficient alcohol to inhibit further growth of Kloeckera. However, Heard and Fleet (1988) report that in mixed culture fermentation, at 10°C (50°F), Kloeckera apiculata remained at a high population density (near 10 CFU/ mL) over the course of fermentation (see Chapter 4). 

Radler et al. (1985) identified strains of H. uvarum that produced killer toxins which had activity toward sensitive strains of S. cerevisiae. Development of these strains also led to high levels of ethyl acetate. 

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Metschnikowia pulcherrima (Candida pulcherrima) Hanseniaspora uvarum (Kloeckera apiculata)... 

Hanseniaspora uvarum (anamorph Kloeckera apiculata) is commonly the major yeast present on the grape berry and in musts and juices, but due to low tolerance to ethanol, populations decline quickly in the presence of Saccharomyces cerevisiae. Strains are typically characterised by low fermentative ability and high production of acetic acid, ethyl acetate and acetaldehyde, which render such strains more suitable to vinegar production. Nevertheless, Ciani and Maccarelli (1998) surveyed 37 isolates and found considerable variability, with some strains producing concentrations of these compounds approaching concentrations present in wines made with Saccharomyces cerevisiae (Table 8D.6). Cofermentation fermentation with Saccharomyces cerevisiae can produce wines with an acceptable balance of volatile and non-volatile compounds and sensory scores (Ciani et al. 2006 Jemec and Raspor 2005 Jolly et al. 2003b Zohre and Erten 2002). 

It is generally accepted that in the case of sound fruit, population density and diversity of native (formerly referred to as wild ) yeasts is limited, ranging from less than 10 to 10 CFU/berry. The most frequently isolated native species are the so-called apiculate yeasts, Kloeckera apiculata, and its sexual counterpart, Hanseniaspora uvarum. These lemon-shaped small yeasts get their name from repeated budding at both poles (see Fig. 3-1) and often account for over 50% of the total yeast flora recovered from fruit. 

To distinguish yeasts that can produce ascospores from those that do not, mycologists use a dual taxonomy for classification. Unfortunately, the nomenclature for anamorph/teleomorph combinations is frequently different. Examples of sexual/asexual or teleomorph/anamorph yeasts include Dekkera/Brettanomyces, Metschnikowia pulcherrima/Candida ptdcher-rima, Hanseniaspora uvarum/Kloeckera apiculata, and Torulaspora delbrueckii/ Candida colliculosa. Some yeasts only exist in the anamorphic form because sporulation has yet to be demonstrated (e.g., Candida vini). 

Species other than Saccharomyces, in particular apiculated yeasts (Hanseniaspora uvarum, Kloeckera apiculata), are present on the grape and are sometimes found at the beginning of fermentations. These species have fewer polymorphous karyotypes and fewer bands than in Saccharomyces. Versavaud et al. (1993) differentiated between strains of apiculated yeast species and Candida famata by using restriction endonucleases at rare sites (Not 1 and Sfl I). The endonucleases cut the chromosomes into a limited number of fragments, which were then separated by pulse-field electrophoresis. 

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