Algal carbohydrates affect polyketide synthesis of the lichen-forming fungus Cladonia rangiferina.
Lichen secondary metabolites (polyketides) are produced by the fungal partner, but the role of algal carbohydrates in polyketide biosynthesis is not clear. This study examined whether the type and concentration of algal carbohydrate explained differences in polyketide production and gene transcription by a lichen fungus (Cladonia rangiferina). The carbohydrates identified from a free-living cyanobacterium (Spirulina platensis; glucose), a lichen-forming alga (Diplosphaera chodatii; sorbitol) and the lichen alga that associates with C. rangiferina (Asterochloris sp.; ribitol) were used in each of 1%, 5% and 10% concentrations to enrich malt yeast extract media for culturing the mycobiont. Polyketides were determined by high performance liquid chromatography (HPLC), and polyketide synthase (PKS) gene transcription was measured by quantitative PCR of the ketosynthase domain of four PKS genes. The lower concentrations of carbohydrates induced the PKS gene expression where ribitol up-regulated CrPKS1 and CrPKS16 gene transcription and sorbitol up-regulated CrPKS3 and CrPKS7 gene transcription. The HPLC results revealed that lower concentrations of carbon sources increased polyketide production for three carbohydrates. One polyketide from the natural lichen thallus (fumarprotocetraric acid) also was produced by the fungal culture in ribitol supplemented media only. This study provides a better understanding of the role of the type and concentration of the carbon source in fungal polyketide biosynthesis in the lichen Cladonia rangiferina.
Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2; and Department of Botany, University of Tanta, Egypt mostafa_elshobary@science.tanta.edu.eg.
Mostafa E
ME
Elshobary
Department of Botany, Faculty of Science, University of Tanta, Egypt.
Mohamed E
ME
Osman
Department of Botany, Faculty of Science, University of Tanta, Egypt.
Atef M
AM
Abo-Shady
Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2.
Emy
E
Komatsu
Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2.
Hélène
H
Perreault
Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2.
John
J
Sorensen
Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2.
Michele D
MD
Piercey-Normore
D001203:Ascomycota / Q000254:growth & development / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000032:analysis*; D002244:Carbon / Q000378:metabolism; D000460:Chlorophyta / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media / Q000737:chemistry; D020869:Gene Expression Profiling; D008011:Lichens / Q000382:microbiology; D048630:Polyketide Synthases / Q000096:biosynthesis; D061065:Polyketides / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D053545:Spirulina / Q000737:chemistry
D002241:Carbohydrates; D003470:Culture Media; D061065:Polyketides; D002244:Carbon; D048630:Polyketide Synthases
HPLC; axenic culture; lichen algae; polyols; qPCR; secondary metabolite