Isolation and Characterization of Four Unreported Penicillium Species Isolated from the Freshwater Environments in Korea.

The fungal species of the genus Penicillium can be found across a diverse array of environments. The infrageneric classification of the genus Penicillium has been studied with comparison of morphological and phylogenetical features, derived into two subgenus, 32 sections, and 89 series. In this study, 11 fungal strains were isolated from freshwater environments, plant litter, and nearby substrates in Korea and were identified as previously unreported species. The internal transcribed spacer (ITS) regions, β-tubulin (BenA), calmodulin (CaM), and RNA polymerase II subunit (RPB2) genes were analyzed for phylogenetic analyses. A neighbor-joining tree was then constructed using the concatenated DNA sequences, and the strains were compared with closely related species of the genus Penicillium. The strain clustered into distinct phylogenetic lineages, confirming their classification as P. contaminatum, P. jinfoshanicum, P. xuanhanense, and P. soppii. NNIBRFG40229 exhibits monoverticillate conidiophores with flask-shaped phialides, characteristic of P. contaminatum; NNIBRFG1595 presents divaricate conidiophores, consistent with P. jinfoshanicum; NNIBRFG5602 shows a velutinous texture with orange pigmentation, resembling P. xuanhanense; and NNIBRFG4602 shows biverticillate conidiophores with cylindrical metulae, corresponding to P. soppii. This study provides the first report of these species in Korea, enhancing taxonomic understanding.