FIG 2.

Absence of intracellular β-glucosidases compromises cellulase induction by lactose. (A) Exoglucanase activity analysis of the culture supernatants of WT and mutant strains deleted for β-glucosidase genes grown on 1% (wt/vol) lactose. The differences between the WT and Δcel1b strains were found to be statistically relevant, by Student's t test, at the later stages of induction (P = 0.025 for 60 h and P = 0.029 for 72 h). (B) Western blot analysis of CBH1 secreted into the culture supernatants of WT and mutant strains grown on 1% (wt/vol) lactose. Equal amounts of culture supernatant relative to biomass were loaded for all strains. (C) Quantitative RT-PCR analysis of gene expression of cbh1 in WT and mutant strains after induction by 1% (wt/vol) lactose for different periods, as indicated. Values in this figure are the means for three biological replicates. Error bars show the SD for these replicates.