†Department of Environmental Science and Analytical Chemistry, Stockholm University, SE-114 18 Stockholm, Sweden.
‡Department of Environmental Chemistry, IDÆA-CSIC, Jordi Girona 18, 08034 Barcelona, Spain.
Environ Sci Technol. 2015 May 5;49(9):5779-87. doi: 10.1021/acs.est.5b00833. Epub 2015 Apr 21.
In polluted environments, contaminant effects may be manifested via both direct toxicity to the host and changes in its microbiota, affecting bacteria-host interactions. In this context, particularly relevant is exposure to antibiotics released into environment. We examined effects of the antibiotic trimethoprim on microbiota of Daphnia magna and concomitant changes in the host feeding. In daphnids exposed to 0.25 mg L(-1) trimethoprim for 24 h, the microbiota was strongly affected, with (1) up to 21-fold decrease in 16S rRNA gene abundance and (2) a shift from balanced communities dominated by Curvibacter, Aquabacterium, and Limnohabitans in controls to significantly lower diversity under dominance of Pelomonas in the exposed animals. Moreover, decreased feeding and digestion was observed in the animals exposed to 0.25-2 mg L(-1) trimethoprim for 48 h and then fed 14C-labeled algae. Whereas the proportion of intact algal cells in the guts increased with increased trimethoprim concentration, ingestion and incorporation rates as well as digestion and incorporation efficiencies decreased significantly. Thus, antibiotics may impact nontarget species via changes in their microbiota leading to compromised nutrition and, ultimately, growth. These bacteria-mediated effects in nontarget organisms may not be unique for antibiotics, but also relevant for environmental pollutants of various nature.
在污染环境中，污染物的影响可能通过对宿主的直接毒性和其微生物组的变化来表现，从而影响细菌-宿主的相互作用。在这种情况下，特别相关的是暴露于释放到环境中的抗生素。我们研究了抗生素甲氧苄啶对大型溞微生物组的影响，以及随之而来的宿主摄食变化。在暴露于 0.25mg/L 甲氧苄啶 24 小时的大型溞中，微生物组受到强烈影响，（1）16S rRNA 基因丰度下降多达 21 倍，（2）在对照组中，由弯曲杆菌、水生菌和 Limnohabitans 主导的平衡群落转变为暴露动物中以 Pelomonas 为主导的群落多样性显著降低。此外，在暴露于 0.25-2mg/L 甲氧苄啶 48 小时并随后喂食 14C 标记藻类的动物中，观察到摄食和消化减少。尽管随着甲氧苄啶浓度的增加，肠道中完整藻类细胞的比例增加，但摄取率、掺入率以及消化和掺入效率显著降低。因此，抗生素可能通过改变其微生物组来影响非靶标物种，导致营养受损，最终生长受损。这些非靶标生物中细菌介导的影响可能不仅对抗生素是独特的，而且对各种性质的环境污染物也是相关的。
