title: Extra- and intracellular lactose catabolism in Penicillium chrysogenum: phylogenetic and expression analysis of the putative permease and hydrolase genes.
abstract: Penicillium chrysogenum is used as an industrial producer of penicillin. We investigated its catabolism of lactose, an abundant component of whey used in penicillin fermentation, comparing the type strain NRRL 1951 with the high producing strain AS-P-78. Both strains grew similarly on lactose as the sole carbon source under batch conditions, exhibiting almost identical time profiles of sugar depletion. In silico analysis of the genome sequences revealed that P. chrysogenum features at least five putative β-galactosidase (bGal)-encoding genes at the annotated loci Pc22g14540, Pc12g11750, Pc16g12750, Pc14g01510 and Pc06g00600. The first two proteins appear to be orthologs of two Aspergillus nidulans family 2 intracellular glycosyl hydrolases expressed on lactose. The latter three P. chrysogenum proteins appear to be distinct paralogs of the extracellular bGal from A. niger, LacA, a family 35 glycosyl hydrolase. The P. chrysogenum genome also specifies two putative lactose transporter genes at the annotated loci Pc16g06850 and Pc13g08630. These are orthologs of paralogs of the gene encoding the high-affinity lactose permease (lacpA) in A. nidulans for which P. chrysogenum appears to lack the ortholog. Transcript analysis of Pc22g14540 showed that it was expressed exclusively on lactose, whereas Pc12g11750 was weakly expressed on all carbon sources tested, including D-glucose. Pc16g12750 was co-expressed with the two putative intracellular bGal genes on lactose and also responded on L-arabinose. The Pc13g08630 transcript was formed exclusively on lactose. The data strongly suggest that P. chrysogenum exhibits a dual assimilation strategy for lactose, simultaneously employing extracellular and intracellular hydrolysis, without any correlation to the penicillin-producing potential of the studied strains.
authors.affiliation: Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Ágota
authors.initials: Á
authors.lastname: Jónás
authors.affiliation: Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Fekete
authors.affiliation: 1] Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary [2] Institut de Génétique et Microbiologie, CNRS UMR 8621, Université Paris-Sud, Orsay, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Flipphi
authors.affiliation: Institute of Food Processing, Quality Assurance and Microbiology, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary.
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Sándor
authors.affiliation: Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Szilvia
authors.initials: S
authors.lastname: Jäger
authors.affiliation: Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Ákos P
authors.initials: ÁP
authors.lastname: Molnár
authors.affiliation: Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Szentirmai
authors.affiliation: Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Levente
authors.initials: L
authors.lastname: Karaffa
mesh_terms: D001089:Arabinose / Q000235:genetics / Q000378:metabolism; D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006867:Hydrolases / Q000235:genetics* / Q000378:metabolism; D007785:Lactose / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D008660:Metabolism; D010406:Penicillins / Q000378:metabolism; D010408:Penicillium chrysogenum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D010406:Penicillins; D001089:Arabinose; D006867:Hydrolases; D001616:beta-Galactosidase; D007785:Lactose