Genomic Analysis, Optimal Growth Conditions, Gene Expression, and Bioactivity of the Entomopathogenic Fungus...

The entomopathogenic fungus Polycephalomyces nipponicus isolate MK1201, obtained from cicada nymph cadavers, produces bioactive compounds, but its genomic features remain largely unexplored. This study analyzed the whole genome of P. nipponicus isolate MK1201 using the Illumina platform, revealing a genome size of 29.85 Mb with a GC content of 53.74%. Secondary metabolite biosynthetic gene clusters, including polyketide synthases (PKSs), non-ribosomal peptide synthetases (NRPSs), and terpene synthases, were identified using antiSMASH. Notably, clusters linked to the biosynthesis of clavaric acid (anticancer) and ε-poly-L-lysine (antimicrobial) were detected. Optimal growth conditions were assessed, showing rapid growth on carbon-rich media and denser mycelial growth on nitrogen-supplemented media. Gene expression analysis confirmed the expression of the NRPS-like gene associated with ε-poly-L-lysine biosynthesis, with the highest expression observed in potato dextrose agar (PDA)-grown mycelia. No detectable expression of the terpene synthase gene associated with clavaric acid biosynthesis was found under the tested conditions. Mycelial extracts exhibited antioxidant activity, with the highest of 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity in peptone- and malt extract-supplemented media [2.03 ± 0.03 and 2.00 ± 0.01 mg Trolox equivalents (TE)/g sample, respectively]. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging activity was highest in PDA extracts (43.39 ± 0.38 mg TE/g sample), while the ferric reducing antioxidant power (FRAP) activity peaked in malt extract extracts (33.62 ± 0.49 mM FeSO4/g sample). Antibacterial assays showed that extracts from malt extract-and beef extract-supplemented media inhibited Bacillus cereus ATCC 11778, with MIC and MBC values of 1.56 mg/mL, reducing biofilm formation by 43.66% and 58.02%, respectively. These findings provide genomic and biochemical insights into P. nipponicus isolate MK1201, highlighting its pharmaceutical and antimicrobial potential.