Abstract

Crangonyx islandicusSvavarsson & Kristjánsson, 2006 is a groundwater amphipod endemic to Iceland and restricted to spring sources at edges of lava fields in the volcanically active zone. Genetic analysis indicate that the amphipod has survived in subglacial refugia in the groundwater in Iceland during past Ice Ages. We investigated the gut bacteria of C. islandicus and compared them with the bacterial diversity identified in biofilms from its groundwater habitat. The diversity of both uncultivated and cultivated bacteria was analyzed using partial 16S rRNA gene sequences. The results show that iron-oxidizing bacteria such as Sideroxydans and Gallionella and the methanotroph Methylobacter are common in the biofilm but absent from the gut samples. Thiomonas was common in both the biofilm and the gut samples. The cultivation of gut bacteria revealed that most of the taxa could be linked with terrestrial soil and/or freshwater habitat based on available database entries. This indicates that the food source for the amphipods is partly of terrestrial origin. The presence of primary producers in the subsurface habitat of C. islandicus indicate that microbial chemolithotrophic activity might fuel the system at least partly and thus explain the amphipod survival in the subsurface of Iceland during repeated glaciation for the past 5 mya.

中文翻译：

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地下水两栖动物肠道菌群Crangonyx islandicus Svavarsson和Kristjánsson，2006年（两栖动物：Crangonyctidae）与其春季源生境中的生物膜的比较

摘要

Crangonyx islandicus Svavarsson＆Kristjánsson，2006年是冰岛特有的地下水两栖动物，在火山活动区的熔岩田边缘仅限于泉源。遗传分析表明，在过去的冰河时期，两栖动物在冰岛地下水的冰川下避难所中幸存下来。我们调查了C. islandicus的肠道细菌，并将其与从其地下水生境的生物膜中鉴定出的细菌多样性进行了比较。使用部分16S rRNA基因序列分析了未培养细菌和已培养细菌的多样性。结果表明，铁氧化细菌如Sideroxydans和Gallionella以及甲烷氧化菌甲基杆菌在生物膜中很常见，但肠道样品中却没有。在生物膜和肠道样品中，硫脲类都很常见。肠道细菌的培养表明，根据可用的数据库条目，大多数分类单元都可以与陆地土壤和/或淡水栖息地联系起来。这表明两栖动物的食物来源部分是陆地来源。C. islandicus地下生境中主要生产者的存在表明，微生物的化学营养性活动可能至少部分为系统提供了燃料，从而解释了过去5 maya反复冰川形成期间两栖动物在冰岛地下的存活。