Identification and Characterization of Eurotium rubrum Isolated from Meju in Korea

Abstract

We isolated and identified a strain of Eurotium rubrum from Meju that has not been reported in Korea. This fungus is yellowish brown; reverse dark brown on CYA and PDA while yellow on 2% MEA at 25°C. Cleistothecia are first bright yellow and gradually turned brown. Mycerial growth on CYA attained a diameter of 30 mm at 20°C, 37 mm at 25°C and 32 mm at 30°C after 15 days. The isolate grew slower on 2% MEA (< 20 mm 15 days at 25°C) compared to CYA and PDA (< 40 mm 15 days at 25°C). Cleistothecia are superficial, yellow to light brown, globose to subglobose, 40~75 μm in diameter. Asci are 8-spored and globose to subglobose 8~11 μm. Ascospores are disciform, 4.0~5.0 μm in length and 4.2~4.5 μm in width. Conidia are ovate or bacillar, finely roughened to densely spinulose, 4.6~6.0 μm in length and 3.0~4.3 μm in width. Compared to known Eurotium rubrum, the Korean isolate showed 99% sequence similarity in ITS rDNA (554 bp) and calmodulin (750 bp) gene and 100% in β-tubulin (1016 bp) gene. The E. rubrum isolate also had weak β-glucosidase and protease activities.

Keywords::

• β-tubulin gene
• Calmodulin gene
• Eurotium rubrum
• ITS rDNA
• Meju