Multilateral budding

Saccharomyces yeasts are rapid fermentors. S. cerevisiae and S. bayanus produce up to 18—20% ethanol. The cells are ovoid to spherical, eUiptical, or elongated (especially under conditions of nitrogen starvation). Vegetative propagation is by multilateral budding. S. uvarum and S. rosei occur earher in the fermentation, when S. rosei may produce up to 6—8% ethanol before being overgrown by the other Saccharomyces yeasts. S. cerevisiae may produce up to 18-20% ethanol (28). 

Fig. 16.1 1. Drawings of (a) S. cerevisiae (multilateral budding) (b) Schizosaccharomyces pombe (binary fission) (c) Nadsonia Sp. (bipolar budding) (d) pseudomycelium of Pichia membranaefaciens. 2. Asci and ascopores of (a) Saccharomyces Sp. (b) Pichia Sp. (hatshaped spores) (c) Hansemla saturnus (saturn-shaped spores).

Cells of brewing strains are usually spherical or ellipsoidal in shape and their size varies between species, strains and even within a culture of a pure strain. Some values for mean diameter (assuming spherical cells) and dry cell mass are given in Table 16.4. All members of the genus Saccharomyces reproduce by multilateral budding. 

Figure 9.9 A schematic representation of the cell cycle of a budding wine yeast cell. Haploid and diploid cells reproduce asexually by multilateral budding during which each cell gives rise to a daughter cell made of entirely new cell surface material. Buds may arise at any point on the mother cell surface, but never again at the same site. Under optimal nutritional and cultural conditions Saccharomyces cerevisiae doubles its mass every 90 min. The cell division cycle consists of four phases Gl, S, G2 and M.

Colony and cell morphology varies with isolation media. Barnett et al. (1983) describe Z bailii as ovoidal to cylindrical in shape (depending on growth medium), in the size range 4.5-11.5 pm x S.5-6.5 pm. The yeast exhibits multilateral budding leading to formation of a simple pseudomycelium. 

Multilateral Budding. Characteristic of Saccharomyces sp., multilateral budding occurs on the shoulder area of the yeast. Each bud arises at a location separate from others. As seen in the electron micrograph (Fig. 3-4), (not visible using a standard compound microscope), upon separa-... 

Microscopic —Oval-shaped vegetative cells on YM agar — Multilateral budding —(1-4) Smooth, round-shaped ascospores on YM agar — Mature club-shaped asci persistent —Rudimentary (simple) pseudomycelium on com meal agar... 

Identification of unknown yeast (obtained by either using the key or the flow chart) Ic Vegetative reproduction by multilateral budding. Go to 5. 

Budding patterns vary depending on culture age, physiological status, and the physical/chemical conditions of culture. For example, Dekkera/ Brettanomyces are described as reproducing asexually through multilateral budding. However, older cells may exhibit a cell shape suggestive of... 

In general, reproduction in the case of Candida is accomplished through multilateral budding. Various sugars may be fermented and nitrate may be assimilated depending on species. Of the sugars tested, Candida stellata... 

As described by Vaughan-Martini and Martini (1998a), Saccharomyces appear microscopically as globose or ovoidal cells with multilateral budding and possibly pseudohyphae (Fig. 1.4). The yeast forms one to four ascospores, which are smooth and ellipsoidal. Colonies appear smooth, usually flat, and occasionally raised and opaque. The two primary species found in wines, S. bay anus and S. cerevisiae (anamorph Candida robusta), ferment glucose, sucrose, and raffinose and assimilate glucose, sucrose, maltose, raffinose, and ethanol but not nitrate. Saccharomyces can not utilize five-carbon sugars (e.g., pentoses). 

Saccharomyces Ascosporogenous yeast, multiply by multilateral budding Prevalent in many food S. cerevisiae Z3... 

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