農業部-水產試驗所全球資訊網農業部-水產試驗所全球資訊網

1998年12月，鹿港地區半淡鹹水養殖之2 ~ 3年生之成年母烏魚 (Mugil cephalus, Linnaaeus)，發生嚴重病害而導致連續性大量死亡，罹病魚外觀瘦弱，活力低下，出現異常行為，食慾減退，體側及腹面出現局部出血及潰瘍區。解剖觀察發現病魚各臟器出現無數的白色結節，脾臟及腎臟最為嚴重。從病魚分離純化出10株細菌，屬於革蘭氏陽性分枝桿菌，以 Ziehl-Neelsen acid-fast 染色呈弱陽性反應。菌株不產生氣生菌絲，不產生可溶性色素或黑色素，最適生長溫度為20 ~ 30 ℃。分析細菌細胞壁組成及全細胞醣類成份，菌株A212及菌株B222細胞壁氨基酸及全細胞醣類成份分別為meso-DAP及galactose、arabinose，屬於chemotype IV A型，菌體含枝菌酸類 (mycolic acid)，menaquinone的種類為MK-8(H4)，主要的脂肪酸結構為直鏈狀，其成份組成為1b type tuberculostearic acid (TBSA)，細菌分類位置屬於nocardioform菌屬。綜合細菌形態學、細菌生化特性試驗、細菌細胞壁及體成份組成分析等，試驗結果將菌株A212及菌株B222鑑定為奴卡氏菌 (Nocardia seriolae)。

This paper describes an investigation on an epizootic of nocardiosis in female broodstock of striped mullet, Mugil cephalus (Linnaeus), cultured in central Taiwan during 1998. The nocardiosis present in the study was a chronic systematic infection in striped mullet. Several diseased fish showed sluggish swimming behavior and skin ulcers. Typical lesions were marked with white nodules and were scattered throughout the gills, liver, spleen, kidney, stomach, intestines, mesentery, and gonads. The most-severe lesions were found in the spleen and kidney.Ten bacterial strains were isolated from the moribund diseased fish and were demonstrated to be gram-positive, branching mycelia, whose fragmentation occurred in a zigzag pattern. The chemotype of the bacterial strains A212 and B222 was type IVA containing meso-DAP, arabinose, and galactose. The predominant menaquinone was MK-8(H4), and mycolic acids were present in the cellular composition. The results suggested that bacterial strains A212 and B222 were Nocardia seriolae.