Penicillium koreense sp. nov., Isolated from Various Soils in Korea

Abstract

During an investigation of the fungal diversity of Korean soils, four Penicillium strains could not be assigned to any described species. The strains formed monoverticillate conidiophores with occasionally a divaricate branch. The conidia were smooth or finely rough-walled, globose to broadly ellipsoidal and $2.5-3.5{\times}2.0-3.0{\mu}m$ size. Their taxonomic novelty was determined using partial ${\beta}$-tubulin gene sequences and the ribosomal internal transcribed spacer region. The phylogenetic analysis showed that the isolates belonged to section Lanata-Divaricata and were most closely related to Penicillium raperi. Phenotypically, the strains differed from P. raperi in having longer and thicker stipes and thicker phialides. Strain KACC $47721^T$ from bamboo field soil was designated as the type strain of the new species, and the species was named Penicillium koreense sp. nov., as it was isolated from various regions in Korea.

Taxonomy

Penicillium koreense S.B. Hong, D.H. Kim & Y.H. You, sp. nov. Fig. 2. In section Lanata-Divaricata in subgenus Aspergilloides. Mycobank (MB808759).

Etymology: N.L. neut adj. koreense, pertaining to Korea, from where the novel fungal species was isolated.

Colony diameters after 7 days at 25℃ (in mm): CYA 32-34; MEA 42-48; CREA 32-35; OA 33-38; CYA at 4℃ no growth; CYA at 30℃ 39-43; CYA at 37℃ 15-19.

Colonies on CYA, mostly velvety with a distinct margin and often floccose, radially sulcate, sporulation moderate to strong, conidia en masse grey-green, exudate present as clear droplets; colony reverse beige. Colonies on MEA, velvety to slightly floccose, conidia en masse grey-green, reverse orange-brown, sporulation moderate to strong. On CREA, no exudate, poor growth (KACC 47721T), but some strains grow well (KACC 46682 and 47720), weak to moderate sporulation and no acid production. Colony on OA, velvety to slightly floccose and good sporulation, reverse light orange-brown. No production of ascomata after 2 weeks on incubation.

Conidiophores, predominantly monoverticillate with occasionally a divaricate branch; stipes smooth-walled, slender and long (200-800 × 2.0-3.0 µm), with vesicular apices up to 3.0-5.0 µm, vesicle bearing 6-10 phialides. Phialides ampulliform with a distinct neck (8.0-11.5 × 3.0-4.0 µm). Conidia smooth or finely rough-walled, globose to broadly ellipsoidal 2.5-3.5 (2.9 ± 0.2) × 2.0-3.0 (2.5 ± 0.1).

Type strain: KACC 47721, isolated from a bamboo field soil in Goryeong, Korea. The culture is preserved in a metabolically inactive state (lyophilization and liquid nitrogen storage) in Korean Agricultural Culture Collection in Suwon, Korea. Molecular markers for the species are KM000846 for β-tubulin, and KJ801939 for rDNA-ITS.

Additional strains studied: KACC 46682 (hot pepper field soil), KACC 47720 (maize field soil), and KACC 47722 (coniferous forest soil).