Laboratory of Environment Biomonitoring, University of Carthage, Faculty of Sciences of Bizerta (FSB), 7021 Zarzouna, Bizerta, Tunisia.
Laboratory of Environment Biomonitoring, University of Carthage, Faculty of Sciences of Bizerta (FSB), 7021 Zarzouna, Bizerta, Tunisia.
Aquat Toxicol. 2020 Nov;228:105632. doi: 10.1016/j.aquatox.2020.105632. Epub 2020 Sep 19.
An experiment was carried out using microcosms to evaluate the impact of the fluoroquinolone antibiotic on nematode trophic groups structure and bacterial abundance. Sediment samples were experimentally enriched with four increasing doses of ciprofloxacin [D1 (50 ppm), D2 (100 ppm), D3 (200 ppm) and D4 (500 ppm)] and compared to non-enriched sediments (used as control). Ciprofloxacin changed the trophic composition of nematodes taxa where the relative abundance of microvores (M), epigrowth feeders (EF) and ciliate consumers (CF), raised in a control microcosm, was highly affected and significantly decreased in response to the increasing doses. Nevertheless, the abundance of deposit feeders (DF), optional predators (FP) and exclusive predators (Pr) showed a significant increase. Results from the multivariate analysis showed a clear impact of this antibiotic on nematode trophic assemblages. Microcosms treated with the three highest doses [D2, D3 and D4] were different from the control. The exceptions were those treated with the lowest dose, D1, and which were grouped with the control. The SIMPER analysis results showed that the average dissimilarity continuously increased in the treated microcosms compared to the control. Furthermore, our results have shown that ciprofloxacin also leads to a significant decrease in bacterial density with the highest dose, which could explain the results obtained for nematode trophic groups distribution. Thus, the bacteriophages nematodes only use bacteria as a nutrition source and the lack or presence in small quantity of this food could induce a decrease in their abundance as well as changing of nematodes groups repartition. Our work demonstrates that the nematode responses were dependent on sediment enrichment with ciprofloxacin and opens new perspectives on the potential impact of antibiotics on functional nematode diversity.
采用微宇宙实验方法评估了氟喹诺酮类抗生素对线虫营养类群结构和细菌丰度的影响。实验中用四种不同浓度的环丙沙星（D1（50ppm）、D2（100ppm）、D3（200ppm）和 D4（500ppm））对沉积物样品进行了人工富化，并与未富化沉积物（对照）进行了比较。环丙沙星改变了线虫分类群的营养组成，对照微宇宙中微食者（M）、表生食性者（EF）和纤毛虫消费者（CF）的相对丰度较高，而随着剂量的增加，这些线虫分类群的相对丰度显著降低。然而，沉积食者（DF）、兼性捕食者（FP）和专性捕食者（Pr）的丰度显著增加。多变量分析结果表明，这种抗生素对线虫营养组合有明显的影响。用三种最高剂量（D2、D3 和 D4）处理的微宇宙与对照不同。例外的是用最低剂量（D1）处理的微宇宙，它们与对照一起被分组。SIMPER 分析结果表明，与对照相比，处理后的微宇宙中平均不相似性连续增加。此外，我们的结果还表明，环丙沙星也会导致细菌密度在最高剂量下显著下降，这可以解释线虫营养类群分布的结果。因此，噬菌线虫仅将细菌作为营养源，而这种食物的缺乏或少量存在可能会导致其丰度下降以及线虫类群重新分布的改变。我们的工作表明，线虫的反应取决于沉积物中环丙沙星的富化，这为抗生素对功能线虫多样性的潜在影响开辟了新的前景。
