Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, United States of America.
PLoS One. 2009 Nov 23;4(11):e7961. doi: 10.1371/journal.pone.0007961.
The nematode Caenorhabditis elegans may be killed by certain pathogenic bacteria and thus is a model organism for studying interactions between bacteria and animal hosts. However, growing nematodes on prey bacteria may influence their susceptibility to potential pathogens. A method of axenic nematode culture was developed to isolate and quantify interactions between C. elegans and potentially pathogenic strains of the Burkholderia cepacia complex. Studying these dynamics in liquid solution rather than on agar surfaces minimized nematode avoidance behavior and resolved more differences among isolates. Most isolates of B. cenocepacia, B. ambifaria and B. cepacia caused 60-80% mortality of nematodes after 7 days, whereas isolates of B. multivorans caused less mortality (<25%) and supported nematode reproduction. However, some B. cenocepacia isolates recovered from chronic infections were much less virulent (5-28% mortality). As predicted, prior diet altered the outcome of interactions between nematodes and bacteria. When given the choice between Burkholderia and E. coli as prey on agar, axenically raised nematodes initially preferred most lethal Burkholderia isolates to E. coli as a food source, but this was not the case for nematodes fed E. coli, which avoided toxic Burkholderia. This food preference was associated with the cell-free supernatant and thus secreted compounds likely mediated bacterial-nematode interactions. This model, which isolates interactions between bacteria and nematodes from the effects of prior feeding, demonstrates that bacteria can influence nematode behavior and their susceptibility to pathogens.
秀丽隐杆线虫可能会被某些致病细菌杀死，因此它是研究细菌与动物宿主相互作用的模式生物。然而，在猎物细菌上培养线虫可能会影响它们对潜在病原体的敏感性。本研究开发了一种无菌线虫培养方法，以分离和量化秀丽隐杆线虫与伯克霍尔德氏菌复合潜在致病菌株之间的相互作用。在液体溶液中研究这些动态，而不是在琼脂表面上，最大限度地减少了线虫的回避行为，并解决了不同分离株之间的更多差异。大多数洋葱伯克霍尔德氏菌、ambifaria 和 cepacia 分离株在 7 天后导致线虫 60-80%的死亡率，而 multivorans 分离株导致的死亡率较低(<25%)，并支持线虫繁殖。然而，一些从慢性感染中回收的洋葱伯克霍尔德氏菌分离株的毒力要低得多（5-28%的死亡率）。正如预测的那样，先前的饮食改变了线虫和细菌之间相互作用的结果。当在琼脂上选择伯克霍尔德氏菌和大肠杆菌作为食物来源时，无菌培养的线虫最初更喜欢大多数致命的伯克霍尔德氏菌分离株作为食物来源，而不是以大肠杆菌为食的线虫，但以大肠杆菌为食的线虫却避免了有毒的伯克霍尔德氏菌。这种食物偏好与无细胞上清液有关，因此分泌的化合物可能介导了细菌-线虫相互作用。这种从先前喂养的影响中分离出细菌和线虫相互作用的模型表明，细菌可以影响线虫的行为及其对病原体的敏感性。
