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Background   Yarrowia lipolytica  is an oleaginous yeast capable of metabolizing glucose to lipids, which then accumulate intracellularly. However, it lacks the suite of cellulolytic enzymes required to break down biomass cellulose and cannot therefore utilize biomass directly as a carbon source. Toward the development of a direct microbial conversion platform for the production of hydrocarbon fuels from cellulosic biomass, the potential for  Y. lipolytica  to function as a consolidated bioprocessing strain was investigated by first conducting a genomic search and functional testing of its endogenous glycoside hydrolases. Once the range of endogenous enzymes was determined, the critical cellulases from  Trichoderma reesei  were cloned into  Yarrowia.Results  Initially, work to express  T. reesei  endoglucanase II (EGII) and cellobiohydrolase (CBH) II in  Y. lipolytica  resulted in the successful secretion of active enzymes. However, a critical cellulase,  T. reesei  CBHI, while successfully expressed in and secreted from  Yarrowia , showed less than expected enzymatic activity, suggesting an incompatibility (probably at the post-translational level) for its expression in  Yarrowia . This result prompted us to evaluate alternative or modified CBHI enzymes. Our subsequent expression of a  T. reesei-Talaromyces emersonii  (Tr-Te) chimeric CBHI,  Chaetomium thermophilum  CBHI, and  Humicola grisea  CBHI demonstrated remarkably improved enzymatic activities. Specifically, the purified chimeric Tr-Te CBHI showed a specific activity on Avicel that is comparable to that of the native  T. reesei  CBHI. Furthermore, the chimeric Tr-Te CBHI also showed significant synergism with EGII and CBHII in degrading cellulosic substrates, using either mixed supernatants or co-cultures of the corresponding  Y. lipolytica  transformants. The consortia system approach also allows rational volume mixing of the transformant cultures in accordance with the optimal ratio of cellulases required for efficient degradation of cellulosic substrates.    Conclusions  Taken together, this work demonstrates the first case of successful expression of a chimeric CBHI with essentially full native activity in  Y. lipolytica , and supports the notion that  Y. lipolytica  strains can be genetically engineered, ultimately by heterologous expression of fungal cellulases and other enzymes, to directly convert lignocellulosic substrates to biofuels.    Electronic supplementary material  The online version of this article (doi:10.1186/s13068-014-0148-0) contains supplementary material, which is available to authorized users.

Engineering towards a complete heterologous cellulase secretome in Yarrowia lipolytica reveals its potential for consolidated bioprocessing