The Composition of Modified BHI Medium for Optimal Growth of Malassezia spp.

Yang, Nam Woong

Abstract

BACKGROUND
There are several media for culture of Malassezia spp., such as Leeming & Notman (LN) medium, modified Leeming & Notman (mLN) medium, Dixon's medium and modified Dixon's medium etc. It is known that Malassezia spp. grow well in these media in general, but the kind and amounts of their ingredients are various and un-uniform according to researchers. Author propose the new and transparent BHI based medium for the optimal growth of Malassezia spp.
OBJECTIVES
The purpose of this study was to design the simple and transparent BHI based medium and find essential ingredients for the growth of M. globosa and M. obtusa.
METHODS
The colony size of eight standard strains (M. dermatis, M. furfur, M. globosa, M. japonica, M. obtusa, M. sloofiae, M. sympodialis, M. yamatoensis) on the modified BHI (mBHI) agar media with different ingredients was observed by naked eye after seven day culture. The compositions of mBHI medium were as follows; mBHI-1 was supplemented with 0.7% dextrose, 1.5% Tween 80, 1% glycerol to BHI medium, mBHI-2 was supplemented with 1.5% Tween 40 to mBHI-1 instead of Tween 80, mBHI-3 was supplemented with 1.5% Tween 60 to mBHI-1 instead of Tween 80, mBHI-4 was added with 0.8% bile salts to mBHI-1. mBHI-5 was supplemented with 1.5% Tween 60 to mBHI-4 instead of Tween 80, and mBHI-6 was supplemented with 1.5% Tween 40 to mBHI-4 instead of Tween 80. pH of six mBHI media was all adjusted to 6.5.
RESULTS
M. furfur & M. japonica were grown well on mBHI-1 agar, but M. globosa & M. obtusa were not grown and others grown poorly. M. globosa & M. obtusa were not grown on mBHI-1 & mBHI-4 containing Tween 80 as lipid source, but others grown on all mBHI media. The media that all eight Malassezia strains grew well were slightly turbid mBHI-5 & transparent mBHI-6 medium.
CONCLUSIONS
M. globosa & M. obtusa need glycerol and bile salts as well as Tween 60 or 40 instead of Tween 80 for growth. M. furfur & M. japonica need not bile salts for growth. Author proposes the transparent modified BHI medium supplemented with 0.7% dextrose, 1.5% Tween 40, 1% glycerol and 0.8% bile salts (mBHI-6) as new standard medium for culture of eight Malassezia species.