A newly designed culture medium for Flavobacterium psychrophilum

A strain of Flavobacterium psychrophilum was isolated on KDM-2 agar, the medium for BKD (bacterial kidney disease) agent, from ayu Plecoglossus altivelis infected with bacterial coldwater disease (BCWD) in Kyoto Prefecture, but it could not grow on modified Cytophaga agar, which has been recommended for the isolation of BCWD agent from ayu. Therefore, a new culture medium for this strain (AK-0206) was designed by modifying KDM-2. As a result, tryptone yeast extract fetal bovine serum (TYFBS) medium consisting of 0.05% tryptone, 0.02% yeast extract and 5% FBS was developed. The TYFBS agar (agar 2%) proved to provide a higher detection rate of F. psychrophilum from non-diseased and diseased ayu than modified Cytophaga and another commonly used medium, tryptone yeast extract salts (TYES) medium.