草蝦(Penaeus monodon)、大正蝦(Penaeus chinensis)養殖池水及蝦肝胰臟內細菌之數值分類研究

Abstract

1990年3月至7月間，由放養蝦苗至成蝦收成的完整蝦期，以每兩星期的間隔，於宜蘭縣五結鄉的兩個草蝦池及一個大正蝦池，採集池水及蝦肝胰臟做細菌相的分析。旨在以數值分類的方波描述蝦池環境（半淡鹹水）及蝦肝胰臟內細菌的組成及變動情形，以建立上述環境中細菌相的基本資料 以Marine Agar 2216 (Difco)及TCBS (Difco)為培養基，在九次採樣中從池水中分離出473株菌株，從蝦體（腸道或肝胰臟）分離出211株菌株，共計683株，於實驗中死亡12株。測定剩餘671株細菌與45株參考菌株之79項形質，然後進行聚類分析（clustering analysis)，將相關係數Sj定為75%以上，可將此671株菌中之495株分成71個共表型族群(phenon)，佔全部分離菌株的74%。這些菌株分別屬於Genera Vibrio, Aeromonas, Pseudomonas, Photobacterium, Alteromonas, Acinetobacter, Alcalixenes, Moraxella, Flavobacterium, Neisseria, Kingella。其餘176株分離菌，包括Vibrio, Pseudomonas Moraxella, Flayobacterium, Alteromonas, Alcaligenes, Aermonas, Neisseria, Acinetobater, kingella, Gram variable rods, Gram positive rods, Gram positive rods及Enterobacteriaceae，則無法聚類在共表型族群中。 本文將分離的細菌分為代謝活潑菌(metabolic-active bacteria)與代謝不活潑菌(metabolic-inactive bacteria)，兩者在人為培養的環境下，生理生化形質有很大的差異，後者在23°C培養時7天始能見到菌落形成；且在自然環境中，代謝不活潑菌常為池水中的優勢菌群，卻不存在於蝦肝胰臟中。 比較養蝦池水及蝦肝胰臟內的細菌相，結果顯示兩者中細菌的組成不同，細菌數量的變動亦無顯著的相關性。草蝦與大正蝦肝胰臟中的細菌組成，則無顯著差異。

671 strains of aerobic and facultative anaerobic, heterotrophic bacteria were isolated from hepatopancreas of giant tiger prawn (Penaeus ponodon) and fleshy prawn (P. chinensis) and their culture water, in I-Lan district during the period of March to July, 1990. Numerical analysis study of the 671 isolates and 45 reference strains were carried out using 79 morphological, biochemical and physiological characters. At similarity values of 75% or above as defined with Sj (Jaccard) coefficient, 495 strains (i.e. 74% of the total isolates) can be clustered to 71 phena; 13 major and 58 minor phena. These clusterable bacteria were tentatively identified as Vibrio, Aeromonas, Pseudomonas, Photobacterium., Alteromonas, Alcaligenes, Acinetobacter, Moraxella, Neisseria, Flavobacterium, and Kingella. While the other 186 strains were unable to cluster, these bacteria include Vibrio, Pseudomonas, Moraxella, Flavobacterium, Alteromonas, Alcalixenes, Aeromonas, Neisseria, Acinetobacter, Kine1la, Enterobacteriaceae, unidentified Gram positive rods and Gram variable rods. Two kinds of bacteria among the isolates were noticed, based on the metabolic activity and growth rate: the metabolic-active group also is fast grower develop a colony larger than 2 ii in a 72h incubation at 23°C, while the metabolic-inactive group also is slow grower can develop a visible colony only after 7 days incubation. The latter are all exclusively water species and far surpass the former in number, but they never present in the prawn’s hepatopancreas except in one case. No significant correlation between the bacterial number and flora of hepatopancreas of both .P. monodon,. chinensis and their inhabited water. Also, no significant difference between the bacterial number and flora of hepatopancreas of P. monodon and P. chinensis were found.