Comparative study on the production of guar alpha-galactosidase by Saccharomyces cerevisiae SU50B and Hansenula polymorpha 8/2 in continuous cultures.
Saccharomyces cerevisiae SU50B and Hansenula polymorpha 8/2, both carrying a multicopy integrated guar alpha-galactosidase, have been cultivated in continuous cultures, using various mixtures of carbon sources and cultivation conditions. Both S. cerevisiae SU50B and H. polymorpha 8/2 are stable and produce high levels of extracellular alpha-galactosidase in continuous cultures for more than 500 h. For these expression systems the strong inducible promoter systems GAL7 and methanol oxidase, respectively, were used. The induction of alpha-galactosidase synthesis by galactose in SU50B is limited by the low galactose uptake. Apart from that, at high dilution rates, the glucose repression is substantial, and a maximal expression level of 28.6 mg of extracellular alpha-galactosidase.g (dry weight) of biomass-1 could be obtained. In H. polymorpha, the induction of alpha-galactosidase synthesis, in addition to methanol oxidase synthesis using formaldehyde, is very effective up to 42 mg of extracellular alpha-galactosidase.g (dry weight) of biomass-1. Productivities in terms of specific production rate enable a good comparison with those of other heterologous expression systems in the literature. The productivities found with S. cerevisiae SU50B and H. polymorpha, 3.25 and 5.5 mg of alpha-galactosidase.g of biomass-1.liter-1.h-1, respectively, rank among the highest reported in the literature. Enzyme production and secretion in H. polymorpha are more complex. A two-peaked optimum is found in enzyme production. No clear explanation of this phenomenon can be given.
Giuseppin
M L
ML
Unilever Research Laboratorium Vlaardingen, The Netherlands.
Almkerk
J W
JW
Heistek
J C
JC
Verrips
C T
CT
D000429:Alcohol Oxidoreductases / Q000096:biosynthesis; D015169:Colony Count, Microbial; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism; D005557:Formaldehyde; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D010843:Pichia / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism; D013045:Species Specificity; D014169:Transformation, Bacterial; D000519:alpha-Galactosidase / Q000096:biosynthesis*
D003470:Culture Media; D005557:Formaldehyde; D000431:Ethanol; D000429:Alcohol Oxidoreductases; C029293:methanol oxidase; D000519:alpha-Galactosidase; D005947:Glucose; D005690:Galactose