The multi-functional cellulase gene, mfc, from Ampullaria crossean was transformed into Volvariella volvacea by PEG-mediated protoplast transformation to improve the biological efficiency and fruiting body yield. PCR and Southern blotting indicated that mfc was integrated into the genomes of four transformants. In laboratory and large scale cultivation experiments, the average biological efficiency of the transformants was 18.39 +/- 1.27% and 27.84 +/- 3.21%, respectively, considerably higher than the corresponding values for untransformed controls of 12.69 +/- 1.31% and 20.63 +/- 2.59%. This is the first report of an improvement in biological efficiency and fruiting body yield of V. volvacea through transgenesis. (C) 2010 Elsevier Ltd. All rights reserved.