New Records of the Psychrophilic Tetracladium Species Isolated from Freshwater Environments in Korea

Abstract

We investigated the diversity of aquatic fungi from freshwater environments in Korea. From the survey of aquatic fungi, three Tetracladium (Leotiomycetes, Helotiales) strains, NNIBRFG814, NNIBRFG1997, and NNIBRFG3891, were isolated from decaying leaves of Fraxinus rhynchophylla located in Taebaek-si, Gangwon-do; freshwater foam in the freshwater of the Gam stream in Gimcheon-si; and from filtered freshwater of the Yangsan stream in Mungyeong-si, Gyeongsangbuk-do, respectively. The isolated fungal strains were identified using ITS sequence analysis and morphological characters. A sequence analysis indicated that the fungal isolates were closely related to Tetracladium breve MK371730 (100%, NNIBRFG814), Tetracladium setigerum KU519120 (98.96%, NNIBRFG1997), and T. marchalianum MK353126 (98.14%, NNIBRFG3891). In terms of growth conditions, it was confirmed that NNIBRFG814 grew best at 20 °C, did not grow above 30 °C, and grew at 5 °C as a psychrophilic fungus. NNIBRFG814 was included in the T. breve clade but its morphology was not similar to that of T. breve. Thus, NNIBRFG814 is a new species, and T. fraxineum sp. nov. NNIBRFG1997 and NNIBRFG3891 are the first records in Korea of T. setigerum and T. marchalianum, respectively.