Genomic sequencing of the native cellobiose-fermenting yeast, Pichia stipitis, revealed seven potential beta-glucosidase genes.  Five of the these have a putative sugar transporter in close proximity; additionally, three of the five with transporters have potential endo-1,4-beta-glucanase genes "clustered" with the transporter and beta-glucosidase. Experimental analysis of transcript levels, through the use of NimbleGen Expression arrays using cells grown aerobically on cellobiose, revealed the induction profiles of transcripts for all seven genes, the putative transporters, and the endo-1,4-beta-glucanases.  One of the clusters that exhibited a high level of induction included the beta-glucosidase BGL5, the putative transporter HXT2.4 and the endo-1,4-beta-glucanase EGC2.  This gene cluster was overexpressed in P. stipitis using the native promoter of each gene.  The resulting strain has an increased capacity for cellobiose fermentation and ethanol production.  To facilitate the overexpression of BGL5 and HXT2.4 in Saccharomyces cerevisiae; the native P. stipitis promoters and terminators were each replaced with the S. cerevisiae TDH3 promoter and terminator.  These recombinant genes were cloned into S. cerevisiae expression vectors, which allowed for their expression in auxotrophic strains.  Experiments were conducted to examine the fermentative capability of the resulting S. cerevisae strain, expressing the P. stipitis BGL5 and HXT2.4 proteins. expression of either gene resulted in the ability of S. cerevisiae to grow on and ferment cellobiose.