Highly efficient transformation of a (hemi-)cellulases-producing fungus Eupenicillium parvum 4-14 by Agrobacterium tumefaciens

The mesophilic fungus Eupenicillium parvum 4-14 is an important producer of thermotolerant hemicellulolytic and cellulolytic enzymes. The aim of this study was to establish a method for genetic manipulation of the fungus by Agrobacterium tumefaciens. The promotor PgpdA of a glyceraldehyde-3-phosphate dehydrogenase gene was isolated from E. parvum 4-14. To transform the fungus, an expression plasmid containing a superfolder green fluorescent protein (sfGFP) gene under the control of PgpdA promotor was constructed using the plasmid pAg1-H3 as a parental plasmid. Using the fungal ascospores as receptor and hygromycin B resistance as a selection marker, the recombinant plasmid was successfully introduced into the fungal cells by A. tumefaciens-mediated transformation (ATMT) method. Acetosyringone (AS) was essential to the successful transformation. The transformation frequency was significantly affected by the co-culture temperature and time, the quantity of fungal spores and the AS concentration. The highest transformation frequency was up to 373 transformants per 105 fungal spores, which was higher than those of other fungal species. The fungal transformants were genetically stable after five subcultures in the absence of antibiotic. GFP protein was strongly expressed in the hypha of fungal transformants. In conclusion, the ATMT is a highly efficient method for genetic manipulation of E. parvum 4-14, and will improve the molecular researches on the fungus.