Melon aroma-producing yeast isolated from coastal marine sediment in Maizuru Bay, Japan

Researches on marine fungi and fungi isolated from marine environments are not active compared with those on terrestrial fungi. The aim of this study was isolation of novel and industrially applicable fungi derived from marine environments. In this study, 16 fungus-like strains, MS1–MS16, were isolated from coastal marine sediment in Maizuru Bay, Japan, under aerobic culture conditions. Phylogenetic analysis of 18S rRNA gene sequences indicated that 10 isolates belonged to Ascomycota, five isolates belonged to Sordariomycetes, two were Dothideomycetes, and three were Saccharomycetes. Liquid and agar potato dextrose cultures of strains MS1 and MS2 isolated from the coastal sediment released a melon-like aroma. Gas chromatography analysis suggested that strains MS1 and MS2 produce four major chemicals associated with a melon aroma, cis-3-hexen-1-ol, cis-6-nonenal, 3,6-nonadien-1-ol, and trans,cis-2,6-nonadienal. The sequence analyses of the 26S rRNA domains 1/2 (D1/D2) and internal transcribed spacer regions indicated that strains MS1 and MS2 were phylogenetically identified as Geotrichum candidum, a well-known yeast used as a cheese starter. These results suggest the future isolations of novel and functional fungi from marine environments.