By altering their habitats, engineering species can improve their own fitness. However, the effect of this strategy on the fitness of coexisting species or on the structure of the respective food web is poorly understood. In this study, bacteria and bacterivorous nematodes with short (Caenorhabditis elegans) and long (Plectus acuminatus) life cycles were exposed to the mucus secreted by the freshwater flatworm Polycelis tenuis. The growth, reproduction, and feeding preferences of the nematodes in the presence/absence of the mucus were then determined. In addition, confocal laser scanning microscopy (CLSM) was used to examine the structural footprint of the mucus and the mucus colonization dynamics of bacteria and protozoans. Mucus exposure resulted in a greater reproductive output in P. acuminatus than in C. elegans. In a cafeteria experiment, both nematode species were attracted by bacteria-rich patches and were not deterred by mucus. CLSM showed that the flatworms spread a layer of polysaccharide-rich mucus ca. 15 µm thick from their tails. Subsequent colonization of the mucus by bacteria and protozoans resulted in an architecture that progressively resembled a complex biofilm. The presence of protozoans reduced nematode reproduction, presumably due to competition for their bacterial food supply. Animal secretions such as mucus may have broader, community-level consequences and contribute to fueling microbial food webs.

中文翻译：

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扁虫粘液是食物网的基础

通过改变栖息地，工程物种可以改善自身的适应能力。但是，这种策略对共存物种的适应性或对各个食物网的结构的影响知之甚少。在这项研究中，细菌和细菌线虫的生命周期短（秀丽隐杆线虫）和生命周期长（尖突线虫）都暴露在淡水扁虫Polycelis tenuis分泌的粘液中。然后确定在有/没有粘液的情况下线虫的生长，繁殖和摄食偏好。此外，共聚焦激光扫描显微镜（CLSM）用于检查粘液的结构足迹以及细菌和原生动物的粘液定植动力学。与粘液线虫相比，暴露于粘液中导致了P. acuminatus更大的生殖产量。在自助餐厅实验中，两种线虫都被富含细菌的斑块所吸引，并不受粘液的阻遏。CLSM显示扁虫传播了一层富含多糖的粘液ca。尾巴的厚度为15 µm。随后细菌和原生动物对粘液的定殖导致了一种逐渐类似于复杂生物膜的结构。原生动物的存在降低了线虫的繁殖，可能是由于竞争其细菌性食物的供应。诸如粘液之类的动物分泌物可能会产生更广泛的社区影响，并助长微生物食物网的生长。随后细菌和原生动物对粘液的定殖导致了一种逐渐类似于复杂生物膜的结构。原生动物的存在降低了线虫的繁殖，可能是由于竞争其细菌性食物的供应。诸如粘液之类的动物分泌物可能会产生更广泛的社区影响，并助长微生物食物网的生长。随后细菌和原生动物对粘液的定殖导致了一种逐渐类似于复杂生物膜的结构。原生动物的存在降低了线虫的繁殖，可能是由于竞争其细菌性食物的供应。诸如粘液之类的动物分泌物可能会产生更广泛的社区影响，并助长微生物食物网的生长。