Ecossa, Giselastrasse 6, 82319 Starnberg, Germany.
Environ Sci Technol. 2011 Dec 1;45(23):10219-25. doi: 10.1021/es2027136. Epub 2011 Nov 4.
Benthic organisms ingest dissolved and particle-bound contaminants together with their food, whereas it is not clear which fraction of the ingested suspension causes the toxic effects. In the standard toxicity test using the nematode Caenorhabditis elegans, the organisms are fed with bacteria that bind contaminants, thus influencing the bioavailability of the contaminants for the organisms. To unravel the role of food bacteria in the toxicity of contaminants in C. elegans, suspensions with varying densities of bacteria were spiked with the toxic metal cadmium (Cd), either via the water or via the bacteria. The toxicity of Cd to C. elegans was clearly related to the uptake of bacteria in the nematode's gut. An increase in the bacterial density resulted in a significant decrease in the toxicity of Cd such that toxic effects better correlated with the aqueous than with the bacterial-bound or total Cd concentrations. The results suggested that the aqueous Cd that was ingested together with the food was the best available fraction and thereby mainly caused the observed toxicity on the reproduction of C. elegans.
底栖生物在摄取食物的同时也会摄入溶解态和颗粒态的污染物，然而，尚不清楚摄入的悬浮液的哪一部分会产生毒性作用。在使用秀丽隐杆线虫进行的标准毒性测试中，生物体以结合污染物的细菌为食，从而影响污染物对生物体的生物利用度。为了揭示食物细菌在秀丽隐杆线虫中污染物毒性的作用，通过水或细菌向含有不同细菌密度的悬浮液中添加有毒金属镉 (Cd)。Cd 对秀丽隐杆线虫的毒性与线虫肠道中细菌的摄取明显相关。细菌密度的增加会显著降低 Cd 的毒性，使得毒性效应与水相 Cd 浓度而非细菌结合态或总 Cd 浓度更好地相关。结果表明，与食物一起摄入的水相 Cd 是最易获得的部分，因此主要导致了观察到的对秀丽隐杆线虫生殖能力的毒性。
