New insights into the gut microbiome in loggerhead sea turtles Caretta caretta stranded on the Mediterranean coast

Caretta caretta is the most common sea turtle species in the Mediterranean Sea. The species is threatened by anthropomorphic activity that causes thousands of deaths and hundreds of strandings along the Mediterranean coast. Stranded turtles are often cared for in rehabilitation centres until they recover or die. The objective of this study was to characterize the gut microbiome of nine sea turtles stranded along the Sicilian coast of the Mediterranean Sea using high-throughput sequencing analysis targeting V3–V4 regions of the bacterial 16S rRNA gene. Stool samples were collected from eight specimens hosted in the recovery centre after a few days of hospitalization (under 7) and from one hosted for many weeks (78 days). To better explore the role of bacterial communities in loggerhead sea turtles, we compared our data with published fecal microbiomes from specimens stranded along the Tuscan and Ligurian coast. Our results highlight that, despite the different origin, size and health conditions of the animals, Firmicutes, Bacteroidetes and Proteobacteria constitute the main components of the microbiota. This study widens our knowledge on the gut microbiome of sea turtles and could be helpful for the set up of rehabilitation therapies of stranded animals after recovery in specialized centres.

蠵龟（Caretta caretta）是地中海海域最常见的海龟物种。该物种受到人为活动的威胁，此类活动在地中海岸沿线造成数千只个体死亡、数百只海龟搁浅。搁浅海龟通常会被送往康复中心接受救护，直至其康复或死亡。本研究旨在针对细菌16S rRNA基因的V3-V4可变区开展高通量测序分析，以此解析地中海西西里岛沿岸搁浅的9只海龟的肠道菌群特征。研究人员从康复中心内8只入院时长不足7天的个体，以及1只入院长达78天的个体身上采集了粪便样本。为深入探究细菌群落对蠵龟的作用，我们将本次研究的数据与已发表的、来自托斯卡纳与利古里亚海岸搁浅海龟个体的粪便菌群数据进行了比对。结果显示，尽管受试海龟的来源、体型及健康状况存在差异，但厚壁菌门（Firmicutes）、拟杆菌门（Bacteroidetes）与变形菌门（Proteobacteria）仍是其肠道菌群的核心组成部分。本研究拓展了我们对海龟肠道菌群的认知，可为专业康复中心针对搁浅海龟的康复治疗方案制定提供参考。