Protein Production in Yeasts

cerevisiae laboratory strains have been selected for unicellular growth and multiple genetic markers, mainly auxotrophies, to enable easy selection. It has become evident recently that auxotrophic markers impair specific growth rate, chronological hfespan [28], and tolerance to high ethanol concentrations [29]. Therefore, it appears advisable to use wild-type strains for industrial production rather than (auxotrophic) laboratory strains. For many other yeast species, this is less of a concern as most of their laboratory strains are nearly wild type. 

The use of yeasts as expression hosts for protein production and their benefits and pitfalls have been discussed in reviews [39-42]. Along with S. cerevisiae, alternative yeasts were developed as protein production hosts, many of them showing higher secretory capacity. These include the methylotrophic species 

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The practical potential of yeast-based production systems has been confirmed by the successful expression of a whole range of proteins of therapeutic interest in such systems. However, a number of disadvantages relating to heterologous protein production in yeast have been recognized. These include ... 

L., Gasser, B. et al (2012) Recombinant protein production in yeasts. Methods Mol Biol, 824, 329-358. 

Porro, D., Sauer, M., Branduardi, P, and Mattanovich, D. 2005. Recombinant protein production in yeasts. Mol Biotechnol, 31 245-59. 

Steinborn, G., Boer, E., Scholz, A. et al. (2006) Application of a wide-range yeast vector (CoMed) system to recombinant protein production in dimorphic Arxula adeninivorans, methylotrophic Hansenula polymorpha and other yeasts. Microbial Cell Factories, 5, 33. 

Morlino, G.B., Tizzani, L., Fleer, R. et al. (1999) Inducible amplification of gene copy number and heterologous protein production in the yeast Kluyveromyces lactis. Applied and Environmental Microbiology, 65 (11), 4808 1813. 

A relatively small number of biotechnology companies operate in the field of recombinant proteins production in plants (Table 6.4). This small number represents roughly one-third of approximately 60 dedicated plant biotechnology companies - an unfavorable comparison to the several hundred small and medium-sized businesses that use bacterial, yeast or animal-based expression platforms and operate in the sector of red biotechnology. The number of plant-made recombinant proteins that have reached the market is also very limited, but has a healthy tendency to grow. 

Gellissen G (2000). Heterologous protein production in methylotrophic yeasts. Appl. Microbiol. Biotechnol. 54 741-750. 

G. (2009) Xplor 2—an optimized transformation/expression system for recombinant protein production in the yeast Arxula adeninivorans. Appl. Microbiol. Biotechnol, 84, 583-594. 

Idiris, A., Tohda, H., Kumagai, H, and Takegawa, K. (2010) Engineering of protein secretion in yeast strategies and impact on protein production. Apjd. Microbiol Biotechnol, 86, 403-417. 

The mmen is not functional at birth and milk is shunted to the abomasum. One to two weeks after birth, the neonate consumes soHd food if offered. A calf or lamb that is nursing tends to nibble the mother s feed. An alternative method of raising the neonate is to remove it from its mother at a very young age, <1 week. A common example of an early weaning situation is the dairy calf that is removed from the cow soon after birth so that the cow s milk supply might be devoted entirely to production. In this instance, the neonate requires complete dietary supplementation with milk replacer. Sources of milk replacer protein have traditionally included milk protein but may also include soybean proteins, fish protein concentrates, field bean proteins, pea protein concentrates, and yeast protein (4). Information on the digestibiUty of some of these protein sources is available (4). 

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). 

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