Penicillium chrysogenum is used as industrial producer of penicillin. We investigated the catabolism of lactose, an abundant component of whey that has been used extensively in pencillin fermentation, comparing NRRL 1951 as a wild8208;type reference with the industrial penicillin8208;producer ASP8208;78. Both strains grew similarly on lactose under batch conditions. The time8208;profile of sugar depletion concurred with the presence of intra8208;Â and extracellular beta8208;1,48208;D8208;galactosidase (bGal) activities. Upon growth on D8208;glucose, D8208; fructose, D8208;xylose, D8208;galactose and glycerol, neither extra8208;Â nor intracellular bGal could be detected. However, L8208; arabinose induced activity to about half the values measured on lactose. The measured bGal activities were similar for the two investigated strains. In silico analysis revealed that P. chrysogenum features at least five putative bGal8208;encoding genes at the annotated loci Pc22g14540, Pc12g11750, Pc16g12750, Pc14g01510 and Pc06g00600. The first two proteins appear to be orthologs of the Aspergillus nidulans intracellular family 2 glycosyl hydrolases AN3201 and AN3200. The latter three P. chrysogenum proteins feature an N8208;terminal secretion signal and appear distinct paralogs to the extracellular bGal from Aspergillus niger, LacA. Transcript analysis of Pc22g14540 and Pc12g11750 showed that they were expressed exclusively in response to lactose but completely repressed on the mixed growth substrate glucose/lactose. Pc16g12750 was seemingly co8208; expressed with the two putative intracellular bGal genes, while its two paralog genes were apparently not transcribed under any condition tested. This expression profile is distinct from those in other ascomycetes, like Trichoderma reesei or A. nidulans, where bGal genes are induced by the monosaccharides D8208;galactose and/or L8208; arabinose.
Full conference title:
11 th European Conference on Fungal Genetics
- ECFG 11th (2012)