Production of aminopeptidase by marine heterotrophic nanoflagellates
Production of aminopeptidase by marine heterotrophic nanoflagellates
复制标题
海洋异养纳米鞭毛虫生产氨肽酶
DOI：
10.3354/ame034129
复制
发表时间：
2004
影响因子：
1.4
通讯作者：
K. Fukami
中科院分区：
文献类型：
--
作者：
B. Mohapatra;K. Fukami
为了检验异养纳米鞭毛虫（HNF）的酶水平受性质上不同的食用细菌影响的假设，比较了以天然细菌群落和5个不同分类群（气单胞菌属、芽孢杆菌属、棒状杆菌属、黄杆菌属和假单胞菌属）的6种细菌菌株饲养的分离的海洋HNF Jakoba libera-5（2）的氨肽酶产生。J. libera-5（2）的氨肽酶活性（总的和游离的）和丰度随食品细菌的类型而显著不同。J. libera-5（2）的总氨肽酶和游离氨肽酶活性和丰度在假单胞菌属中最大，其次是黄杆菌属和作为猎物的天然细菌群落。在假单胞菌属中，J. libera-5（2）的总氨肽酶活性值，黄杆菌和自然界细菌群落分别为140 ± 6.78 ~ 285 ± 12.36，123 ± 11.17和38 ± 0.56 μmol h-1 l-1，游离氨肽酶活性分别为83 ± 6.15 ~ 137 ± 5.83，分别为82 ± 12.18和8 ± 0.14 μmol h-1 l-1。J. libera-5（2）在摄食气单胞菌、芽孢杆菌和棒状杆菌时，不产生任何可检测量的总氨肽酶和游离氨肽酶。对一株假单胞菌（Pseudomonas sp.）放牧过程中产生的部分纯化的J. libera-5（2）氨肽酶的化学性质进行了研究，结果表明该酶是一种金属螯合剂敏感的碱性丝氨酸氨肽酶，其最适活性为pH8.0和30°C，不受海水中主要阳离子如Na +、Ca 2+和Mg 2+的影响。结果表明，至少有一些海洋HNF可能显着有助于在海洋环境中的酶池，而选择性放牧的细菌。
In order to examine the hypothesis that the enzyme levels of heterotrophic nanoflagel- lates (HNF) are influenced by qualitatively different food bacteria, the production of aminopeptidase by an isolated marine HNF Jakoba libera-5(2) fed on natural communities of bacteria and 6 bacterial strains of 5 different taxonomic groups (Aeromonas, Bacillus, Coryneforms, Flavobacterium and Pseudomonas) were compared. The aminopeptidase activity (total and free) and abundance of J. libera-5(2) significantly differed with the types of food bacteria. The total and free aminopeptidase activities and abundance of J. libera-5(2) were at a maximum with Pseudomonas spp., followed by Flavobacterium sp. and natural communities of bacteria as prey. The values of total aminopeptidase activity of J. libera-5(2) with Pseudomonas spp., Flavobacterium sp. and natural communities of bac- teria were 140 ± 6.78 to 285 ± 12.36, 123 ± 11.17 and 38 ± 0.56 µmol h -1 l -1 , respectively, and those of free aminopeptidase activity were 83 ± 6.15 to 137 ± 5.83, 82 ± 12.18 and 8 ± 0.14 µmol h -1 l -1 , respec- tively. J. libera-5(2) did not produce any detectable amounts of total and free aminopeptidase while grazing on Aeromonas, Bacillus and Coryneforms. The chemical characterization of partially purified aminopeptidase of J. libera-5(2) produced during grazing on a strain of Pseudomonas sp. indicated the enzyme to be metal-chelater-sensitive alkaline serine aminopeptidase with optimal activity at pH 8.0 and 30°C; it was not affected by the major cations of seawater, such as Na + , Ca 2+ and Mg 2+ . The results suggest that at least some marine HNF may significantly contribute to the enzyme pool in marine environments while selectively grazing on bacteria.