Centre for Limnology, Estonian University of Life Sciences, Tartu, Estonia.
Institute of Technology, University of Tartu, Tartu, Estonia.
Mol Ecol. 2023 Dec;32(23):6631-6643. doi: 10.1111/mec.16628. Epub 2022 Aug 21.
The gut microbiome is one of the most important sites of host-microbe interactions, however, mechanisms governing the responses of host-associated microbes to changing environmental conditions are poorly understood. To address this, we investigated individual and combined effects of dietary changes and increase in salinity (from freshwater to salinity 3) or antibiotic concentration on the gastrointestinal bacterial community of the aquatic snail Ampullaceana balthica. In parallel, the energy reserves of the host were quantified. A change of natural food source to biofilm forming green algae Scenedesmus obliquus as well as the combined treatment of salinity and S. obliquus decreased the richness and changed the composition of the A. balthica gastrointestinal bacterial community. In these treatments Pseudomonas became the dominant bacterium. However, energy reserves of the host were higher in these treatments compared to the reference aquaria specimens and the combined treatment of antibiotics with S. obliquus. The presence of antibiotics inhibited the dominance of Pseudomonas and resulted in lower energy reserves despite S. obliquus feeding. Therefore the host seems to be able to adapt and replace its bacterial community composition to respond to mild changes in salinity and food source. Antibiotics in the water can disturb this self-regulating mechanism. Our study underlines the ability of aquatic macroinvertebrates to respond to sudden changes in food source and mild shifts in salinity. Moreover, it emphasizes the strong impact of the food source on the gastrointestinal microbiome and the importance of generalists during disturbance.
肠道微生物组是宿主-微生物相互作用最重要的场所之一，然而，宿主相关微生物对环境变化的反应机制仍知之甚少。为了解决这个问题，我们研究了饮食变化以及增加盐度（从淡水到盐度 3）或抗生素浓度对水生蜗牛 Ampullaceana balthica 胃肠道细菌群落的个体和综合影响。同时，还定量了宿主的能量储备。将天然食物来源改为形成生物膜的绿藻 Scenedesmus obliquus，以及盐度和 S. obliquus 的联合处理，减少了 A. balthica 胃肠道细菌群落的丰富度并改变了其组成。在这些处理中，假单胞菌成为优势细菌。然而，与参考水族标本相比，这些处理中宿主的能量储备更高，而抗生素与 S. obliquus 的联合处理也是如此。抗生素的存在抑制了假单胞菌的优势，尽管有 S. obliquus 喂养，但仍导致能量储备降低。因此，宿主似乎能够适应并取代其细菌群落组成，以应对盐度和食物源的轻微变化。水中的抗生素会干扰这种自我调节机制。我们的研究强调了水生大型无脊椎动物对食物源突然变化和盐度轻微变化的适应能力。此外，它还强调了食物源对胃肠道微生物组的强烈影响以及在受到干扰时广食性生物的重要性。
