The Microbiota of Freshwater Fish and Freshwater Niches Contain Omega-3 Fatty Acid-Producing Shewanella Species
The Microbiota of Freshwater Fish and Freshwater Niches Contain Omega-3 Fatty Acid-Producing Shewanella Species
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DOI：
10.1128/aem.02266-15
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发表时间：
2016-01-01
影响因子：
4.4
通讯作者：
Munro, James B.
中科院分区：
文献类型：
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作者：
Dailey, Frank E.;McGraw, Joseph E.;Munro, James B.
大约30年前，从寒冷的海洋深处分离的自由生活细菌被发现可以产生多不饱和脂肪酸(PUFA)，如二十碳五烯酸(EPA)(20：5N-3)或二十二碳六烯酸(DHA)(22：6N-3)，这两种多不饱和脂肪酸对人类健康至关重要。许多实验室还发现，可以从富含omega-3脂肪酸的海鱼的肠道中分离出产生EPA和/或DHA的细菌，其中许多是希瓦氏菌属的成员。如果细菌总体上为宿主鱼贡献了omega-3脂肪酸，或者如果它们帮助某些细菌物种适应寒冷，那么寒冷的淡水鱼或栖息地也应该容纳这些生产者。因此，我们进行了一项研究，看看这些利基市场是否也含有omega-3脂肪酸生产商。我们成功地从三种严格的淡水本地鱼种，即湖泊白鱼(Coregonus Clupeaformis)、瘦湖鲑鱼(Salvelinus Namaycush)和大眼鱼(Sander Vitreus)，以及从另外两种淡水非本地鱼类，即Coho鲑鱼(Oncorhynchus Kisutch)和西弗伦褐鲑鱼(Salmo Trutta)中分离和鉴定了独特的产生EPA的希瓦纳氏菌。我们还从淡水栖息地分离出四种独特的自由生活的产生EPA的希瓦氏菌。系统发育和表型分析表明，一个生产者显然是Morhuae希瓦氏菌的成员，另一个生产者是海洋生产多不饱和脂肪酸的波罗的海希瓦纳氏菌的姐妹。然而，其余的分离株有更模糊的亲缘关系，与不产生多不饱和脂肪酸的腐败希瓦氏杆菌分离株有共同的祖先，而不是海洋分离的波罗的海链球菌，尽管其表型与波罗的海链球菌更一致。
Approximately 30 years ago, it was discovered that free-living bacteria isolated from cold ocean depths could produce polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) (20:5n-3) or docosahexaenoic acid (DHA) (22:6n-3), two PUFA essential for human health. Numerous laboratories have also discovered that EPA- and/or DHA-producing bacteria, many of them members of the Shewanella genus, could be isolated from the intestinal tracts of omega-3 fatty acid-rich marine fish. If bacteria contribute omega-3 fatty acids to the host fish in general or if they assist some bacterial species in adaptation to cold, then cold freshwater fish or habitats should also harbor these producers. Thus, we undertook a study to see if these niches also contained omega-3 fatty acid producers. We were successful in isolating and characterizing unique EPA-producing strains of Shewanella from three strictly freshwater native fish species, i.e., lake whitefish (Coregonus clupeaformis), lean lake trout (Salvelinus namaycush), and walleye (Sander vitreus), and from two other freshwater nonnative fish, i.e., coho salmon (Oncorhynchus kisutch) and seeforellen brown trout (Salmo trutta). We were also able to isolate four unique free-living strains of EPA-producing Shewanella from freshwater habitats. Phylogenetic and phenotypic analyses suggest that one producer is clearly a member of the Shewanella morhuae species and another is sister to members of the marine PUFA-producing Shewanella baltica species. However, the remaining isolates have more ambiguous relationships, sharing a common ancestor with non-PUFA-producing Shewanella putrefaciens isolates rather than marine S. baltica isolates despite having a phenotype more consistent with S. baltica strains.