Kivistik Carmen, Käiro Kairi, Tammert Helen, Sokolova Inna M, Kisand Veljo, Herlemann Daniel P R
Estonian University of Life Sciences, Center for Limnology, Tartu, Estonia.
Department of Marine Biology, Institute for Biological Sciences, University of Rostock, Rostock, Germany.
Front Microbiol. 2022 Aug 30;13:767334. doi: 10.3389/fmicb.2022.767334. eCollection 2022.
Environmental disturbances influence bacterial community structure and functioning. To investigate the effect of environmental disturbance caused by changes in salinity on host-protected bacterial communities, we analyzed the microbiome within the gastrointestinal tract of in different salinities. is a benthic gastropod found in fresh- and mesohaline waters. Whereas the total energy reserves of were unaffected by an increase of salinity to 3, a high mortality rate was detected after a shift from freshwater to salinity 6 suggesting a major disruption of energy homeostasis. The shift to salinity 6 also caused a change in the gastrointestinal bacterial community composition. At salinity 3, the bacterial community composition of different host individuals was related either to the freshwater or salinity 6 gastrointestinal bacterial community, indicating an ambivalent nature of salinity 3. Since salinity 3 represents the range where aquatic gastropods are able to regulate their osmolarity, this may be an important tipping point during salinization. The change in the intestinal microbiome was uncoupled from the change in the water bacterial community and unrelated to the food source microbiome. Our study shows that environmental disturbance caused by salinity acts also on the host-protected microbiome. In light of the sea-level rise, our findings indicate that salinization of the near-shore freshwater bodies will cause changes in organisms' intestinal microbiomes if a critical salinity threshold (presumably ∼3) is exceeded.
环境干扰会影响细菌群落结构和功能。为了研究盐度变化引起的环境干扰对宿主保护的细菌群落的影响，我们分析了处于不同盐度下的[某种生物]胃肠道内的微生物群。[某种生物]是一种在淡水和中盐度水域中发现的底栖腹足类动物。虽然盐度增加到3时，[某种生物]的总能量储备未受影响，但从淡水转变到盐度6后检测到高死亡率，这表明能量稳态受到了重大破坏。转变到盐度6也导致了胃肠道细菌群落组成的变化。在盐度3时，不同宿主个体的细菌群落组成要么与淡水胃肠道细菌群落相关，要么与盐度6胃肠道细菌群落相关，这表明盐度3具有矛盾的性质。由于盐度3代表了水生腹足类动物能够调节其渗透压的范围，这可能是盐渍化过程中的一个重要临界点。肠道微生物群的变化与水体细菌群落的变化无关，也与食物源微生物群无关。我们的研究表明，盐度引起的环境干扰也作用于宿主保护的微生物群。鉴于海平面上升，我们的研究结果表明，如果超过临界盐度阈值（可能约为3），近岸淡水水体的盐渍化将导致生物体肠道微生物群的变化。
