FIG. 4.

Effect of additional copies of the A. tubingensis xlnA gene integrated into the genome of A. niger N902::pIM230-3 (10 copies of xlnR) (lane 1) on the transcription of xylan- and cellulose-degrading genes. Strain N902::pIM230::pIM101-6 contains 20 xlnA copies (lane 2), strain N902::pIM230::pIM101-10 contains 6 xlnA copies (lane 3), and strain N902::pIM230::pIM101-12 contains 2 xlnA copies (lane 4). The strains were cultured for 18 h on 3% (wt/vol) d-fructose, and mycelia were subsequently transferred to 1% (wt/vol) d-xylose and grown for 8 h. Blots were hybridized with gene-specific probes as indicated and with an 18S rRNA probe as the loading control.