초록
<P><B>Abstract</B>Background<P>Sustainable utilization of plant biomass as renewable source for fuels and chemical building blocks requires a complex mixture of diverse enzymes, including hydrolases which comprise the largest class of lignocellulolytic enzymes. These enzymes need to be available in large amounts at a low price to allow sustainable and economic biotechnological processes.</P><P>Over the past years <I>Pichia pastoris</I> has become an attractive host for the cost-efficient production and engineering of heterologous (eukaryotic) proteins due to several advantages.</P>Results<P>In this paper codon optimized genes and synthetic alcohol oxidase 1 promoter variants were used to generate <I>Pichia pastoris</I> strains which individually expressed cellobiohydrolase 1, cellobiohydrolase 2 and beta-mannanase from <I>Trichoderma reesei</I> and xylanase A from <I>Thermomyces lanuginosus</I>. For three of these enzymes we could develop strains capable of secreting gram quantities of enzyme per liter in fed-batch cultivations. Additionally, we compared our achieved yields of secreted enzymes and the corresponding activities to literature data.</P>Conclusion<P>In our experiments we could clearly show the importance of gene optimization and strain characterization for successfully improving secretion levels. We also present a basic guideline how to correctly interpret the interplay of promoter strength and gene dosage for a successful improvement of the secretory production of lignocellulolytic enzymes in <I>Pichia pastoris</I>.</P></P>