Molecular-genetic diversity of the ascomycetous yeast genus Arthroascus: Arthroascus babjevae sp. nov., Arthroascus fermentans var. arxii var. nov. and geographical populations of Arthroascus schoenii.

Using molecular and genetic analyses, 28 Arthroascus strains were analysed, isolated from widely different geographical localities in Europe, North America, Far-East Asia and Hawaii. Most of the strains have been assigned to the species Arthroascus schoenii. PCR-RAPD revealed two Japanese Arthroascus strains (UCD 67-278 and IFO 10138) to have peculiar patterns. Comparative rDNA (D1/D2 26S, ITS1 and ITS2) sequence analysis showed that the two strains respectively represent a novel species and a novel variety. Based on the results of sequence analysis, genetic hybridization and DNA-DNA reassociation, two new members of the genus Arthroascus are formally described, Arthroascus babjevae sp. nov. (type strain UCD 67-278(T)=CBS 9167(T)) and Arthroascus fermentans var. arxii var. nov. (type strain IFO 10138(T)=CBS 9168(T)). These results show that A. schoenii has a worldwide distribution, while the species Arthroascus javanensis is represented only by the type culture CBS 2555(T), isolated in Indonesia. Cluster analysis revealed a correlation between PCR-RAPD fingerprints and geographical origin of the A. schoenii strains. Despite this molecular differentiation, A. schoenii strains collected in different regions of the world formed predominantly fertile hybrids, with normal recombination of control markers.