Saccharomyces cerevisiae

Saccharomyces cerevisiae Good secretion machinery Post-translational modifications Easy scale-up Selection procedure required Tendency to overglycosylation Thick cell wall complicates purification 

Schizosacharomyces pombe Genetics well understood Mammalian promoters applicable Selection procedure required 

Pichia pastoris High GPCR expression levels Selection procedure required 

Baculovirus Improved procedure Infection of insect cells High expression yields Relatively slow virus production Different post-translational processing 

Stable mammalian High authenticity Large-scale set up Slow procedure to generate cell lines Low recombinant protein yields Stability problems 

The best known catabolic pathways of nitrogenous compounds are those of arginine, proline, allantoin and 4-aminobutyrate (GABA) degradation. Each of these is inducible under specific conditions, and all are subject to nitrogen-catabo-lite repression (see [7,9] and section 6.3). 

General characteristics of amino acid transporters in Saccharomyces cerevisiae 

In Saccharomyces cerevisiae, as in most eukaryotic cells, the plasma membrane is not freely permeable to nitrogenous compounds such as amino acids. Therefore, the first step in their utilization is their catalyzed transport across the plasma membrane. Most of the transported amino acids are accumulated inside the yeast cells against a concentration gradient. When amino acids are to be used as a general source of nitrogen, this concentration is crucial because most enzymes which catalyze the first step of catabolic pathways have a low affinity for their substrates. 

In relationship to their living conditions, yeasts like Saccharomyces cerevisiae have developed a large number of transport systems which take up nitrogenous substances present in the external medium, and accumulate them in unmodified form (for 

---

Alcoholic Fermentation. Certain types of starchy biomass such as com and high sugar crops are readily converted to ethanol under anaerobic fermentation conditions ia the presence of specific yeasts Saccharomyces cerevisia and other organisms (Fig. 6). However, alcohoHc fermentation of other types of biomass, such as wood and municipal wastes that contain high concentrations of cellulose, can be performed ia high yield only after the ceUulosics are converted to sugar concentrates by acid- or enzyme-catalyzed hydrolysis ... 

Saccharomyces cerevisiae is well characterized biochemically and genetically and was the organism of choice for most of the eady experiments. However, heterologous expression seems to be better in some of the industrial strains of yeasts such as Pichiapastoris Hansenulapolymorpha Kluyveromyces lactis and Yarrowia lipolytica (25—28). 

Yeast. The advantages of expression in yeast include potentially high level production of proteins, the abiUty to have expressed proteins secreted into the media for ease of purification, and relatively low cost, easy scale-up. A disadvantage is that plasmid instabiUty may be a problem which can lead to low product yield. Whereas post-translational modification occurs in yeast, proteins are quite often hyperglycosylated. This is generally a problem with expression in Saccharomyces cerevisiae but not for the more recently used yeast host Pichiapastoris (25) (see Yeasts). 

Saccharomyces cerevisiae S. cerevisiae var. ellipsoideus S. carlsbergensis S.fragilis S. rouxii S. delbrueckii... 

R Sanchez, A Sail. Large-scale protein structure modeling of the Saccharomyces cerevisiae genome. Proc Natl Acad Sci USA 95 13597-13602, 1998. 

Trehalose is particularly well-suited for this purpose and has been shown to be superior to other polyhydroxy compounds, especially at low concentrations. Support for this novel idea comes from studies by P. A. Attfield, which show that trehalose levels in the yeast Saccharomyces cerevisiae increase significandy during exposure to high salt and high growth temperatures—the same conditions that elicit the production of heat-shock proteins ... 

Wttfield, P. A., 1987. Trehalo.se accnmnlates in Saccharomyces cerevisiae cXiirin exposure to agents that induce heat shock respon.se.s. FEES Letters 225 259. 

If a phylogenetic comparison is made of the 16S-Iike rRNAs from an archae-bacterium Halobacterium volcanii), a eubacterium E. coli), and a eukaryote (the yeast Saccharomyces cerevisiae), a striking similarity in secondary structure emerges (Figure 12.40). Remarkably, these secondary structures are similar despite the fact that the nucleotide sequences of these rRNAs themselves exhibit a low degree of similarity. Apparently, evolution is acting at the level of rRNA secondary structure, not rRNA nucleotide sequence. Similar conserved folding patterns are seen for the 23S-Iike and 5S-Iike rRNAs that reside in the... 

Alternative Step D Reduction with a Reductate — Sucrose (1 kg) is dissolved in water (9 liters) in a 20-liter bottle equipped with a gas trap. Baker s yeast Saccharomyces cerevisiae, 1 kg) is made into a paste with water (1 liter) and added to the sucrose solution with stirring. After lively evolution of gas begins (within 1 to 3 hours), 3-morpholino-4-(3-tert-butylamino-2-oxopropoxy)-1,2,5-thiadiazole hydrogen maleate [1.35 mols, prepared by reaction of the 3-morpholino-4-(3-tert-butylamino-2-oxopropoxy)-1,2,5-thiadiazole with an equimolar quantity of maleic acid in tetrahydrofuran]. The mixture is allowed to stand until fermentation subsides, after which the bottle is kept in a 32°C incubator until all fermentation has ended (in approximately 1 to 3 days). The yeast is filtered off with addition of diatomaceous earth and the filtrate is evaporated to dryness to give S-3-mor-pholino-4/3-tert-butylamino-2-hydroxypropoxy)-1,2,5-thiadiazole, MP 195° to 198°C (as hydrogen maleate), according to U.S. Patent 3,619,370. 

Saccharomyces cerevisiae Steptomyces roseochromogene Rhizopus nigrans Curvularia lunata Corynebacterium sp... 

For preparative purposes fermenting baker s yeast (Saccharomyces cerevisiae) is commonly used instead of a purified enzyme preparation. However, isolated pyruvate decarboxylates can also be used30. In this context, the most important substrate is benzaldehyde31 which is converted by n-glucosc fermenting yeast to (7 )-l-hydroxy-l-phenyl-2-propanone. This conversion has gained considerable industrial importance because ( )-l-hydroxy-1-phenyl-2-propanonc is an important precursor for the synthesis of (-)-cphedrin. 

The yeast pyruvate decarboxylase is rather specific with respect to the acyl moiety that is added to the aldehyde. Only a few 2-oxo acids can be used as acyl donors besides pyruvic-acid39. For example, treatment of benzaldehyde with 2-oxobutanoic acid and 2-oxopentanoic acid, respectively, and prewashed Saccharomyces cerevisiae gave the corresponding (/ )-acyloin derivatives in 15 25% yield with an enantiomeric excess >95%. 

Ethanol (non-beverage) Saccharomyces cerevisiae Fine chemicals... 

Wang et al.2 and Najafpour et al.3A worked with immobilised microbial cells of Nitrobacer agilis, Saccharomyces cerevisiae and Pseudomonas aeruginosa in gel beads, respectively. They found separately that the cells retained more than 90% of their activity after immobilisation by using specific oxygen uptake rate (SOUR) [mg 02g 1 (dry biomass) h 11 as the biomass activity indicator. Such differences in immobilised biomass and activity between free and immobilised biomass activities depend strongly on the particular characteristics of the microbial systems and their interaction with the support matrix. 

CASE STUDY ETHANOL FERMENTATION IN AN IMMOBILISED CELL REACTOR USING SACCHAROMYCES CEREVISIAE... 

Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilised cell reactor (ICR), was successfully carried out to improve the performance of the... 

Keywords immobilised cell reactor (ICR) Saccharomyces cerevisiae ethanol fermentation encapsulated beads calcium alginate... 

Owing to diminishing fossil fuel reserves, alternative energy sources need to be renewable, sustainable, efficient, cost-effective, convenient and safe.1 In recent decades, microbial production of ethanol has been considered as an alternative fuel for the future because fossil fuels are depleting. Several microorganisms, including Clostridium sp. and yeast, the well-known ethanol producers Saccharomyces cerevisiae and Zymomonas mobilis, are suitable candidates to produce ethanol.2,3... 

Dining batch fermentation of Saccharomyces cerevisiae, other influential parameters can adversely influence the specific rate of growth, and inhibition can be caused either by... 

Najafpour, G.D., Younesi, H. and Ku Ismail, K.S., Ethanol Fermentation in Immobilized Cell Reactor (ICR) Using Saccharomyces cerevisiae , Bioresource Technology, vol. 92/3, 2004, pp. 251-260. 

Saccharomyces cerevisiae Hydrocyalkyl methacrylate Killer toxin ... 

Escherichia coli CH177O049N024 Saccharomyces cerevisiae CHL64O0 52Nai6 Candida utilis CH1i83Ooi54Noi1o... 

Saccharomyces cerevisiae is anaerobically grown in a continuous culture at 30°C. Glucose is used as substrate and ammonia as nitrogen source. A mixture of glycerol and ethanol is produced. At steady-state condition mass the flow rate is stated. The following reaction is proposed for the related bioprocess 4,6... 

---