Penicillium Arizonense as a Novel Producer Strain for Mycophenolic Acid and Expression Analysis of Biosynthesizing Gene Clusters

Abstract A novel potent mycophenolic acid (MPA) producer strain of the genus Penicillium was isolated from refrigerated Mozzarella cheese and identified as P. arizonenseHEWt1. The molecular mechanism of MPA production by this new isolate was our main target. To achieve this objective, we first isolated three MPA overproducer mutants by exposing the wild type to different doses of gamma-rays, and the fermentation conditions for the highest production of MPA by both the wild type and mutants were optimized. Then, orthologs of MPA gene clusters in P. brevicompactum were cloned and predicted from the genome of P. arizonense. Sequencing and bioinformatic analysis proved the presence of a cluster containing five putative genes in the P. arizonense HEWt1 genome ortholog to the MPA cluster, mpaA, mpaC, mpaF, mpaG, and mpaH. All predicted genes displayed 96-97% similarity with the related hypothetical protein of P. arizonense. The genes, mpaG, mpaC, and mpaF. represented 69%, 82%, 84%, respectively, similarity with their orthologous genes in P. brevicompactum, whereas mpaG and mpaA represented 75% and 79%, respectively, similarity to their orthologous genes in P. roqueforti. Gene expression analysis through quantitative rPCR indicated an increase in the transcription value of all annotated genes in the three mutants over the wild type. A highly significant increase in the gene expression of mpaC, mpaF, and mpaH was observed, with 8.4561±1.02, 5.6569±0.87, and 4.6268±0.18-fold increases, respectively, in P. arizonense-MT1 compared with wild-type. These results confirmed the potential participation of these genes in MPA biosynthesis and are the first report regarding the molecular mechanism of MPA production by P. arizonense.