Corporación Colombiana de Investigación Agropecuaria, AGROSAVIA, Sede Central, Mosquera, Colombia.
Universidad Nacional de Colombia, Sede Bogotá, Colombia.
Exp Parasitol. 2021 Dec;231:108172. doi: 10.1016/j.exppara.2021.108172. Epub 2021 Nov 10.
The nematophagous fungus Duddingtonia flagrans is used in integrated management of gastrointestinal nematodes in ruminants. The chlamydospores of the fungus, orally administered, pass through the segments of the ruminant digestive tract and, in the feces, capture the nematodes preventing their migration to grasslands. The drastic conditions of the gastrointestinal segments can negatively affect the fungus' biocontrol activity. The aim of this study was to assess the effect of in vitro conditions of the sheep's main gastrointestinal segments on the concentration, viability and nematode predatory ability of D. flagrans chlamydospores. The segments evaluated separately in vitro were the oral cavity, rumen, abomasum, and small intestine. The results showed that chlamydospores concentration was not affected by exposure to the different segments. The viability of the chlamydospores after exposure to the oral cavity (2.53 × 10 CFU/mL) and small intestine (1.24 × 10 CFU/mL) was significantly lower than its control treatment, with values of 6.67 × 10 CFU/mL and 2.31 × 10 CFU/mL respectively. Nematode predatory ability after rumen exposure was reduced by 7% compared to the control treatment, by 25% after abomasum exposure and by 17% after small intestine. This study revealed the individual in vitro effect of each segment of ovine gastrointestinal tract on the integrity of this strain of the fungus D. flagrans affecting its viability and nematode predatory ability under the evaluated conditions. Delivery systems could be designed to protect chlamydospores considering the impact of each gastrointestinal segment.
食线虫真菌杜氏藻被用于反刍动物胃肠道线虫的综合管理。真菌的厚垣孢子经口给药后通过反刍动物消化道的节段，在粪便中捕获线虫，防止其迁移到草原。胃肠道节段的恶劣条件会对真菌的生物防治活性产生负面影响。本研究旨在评估绵羊主要胃肠道节段的体外条件对 D. flagrans 厚垣孢子浓度、活力和线虫捕食能力的影响。分别在体外评估的节段是口腔、瘤胃、皱胃和小肠。结果表明，厚垣孢子浓度不受暴露于不同节段的影响。暴露于口腔（2.53×10 CFU/mL）和小肠（1.24×10 CFU/mL）后的厚垣孢子活力明显低于对照处理，分别为 6.67×10 CFU/mL 和 2.31×10 CFU/mL。与对照处理相比，暴露于瘤胃后的线虫捕食能力降低了 7%，暴露于皱胃后的线虫捕食能力降低了 25%，暴露于小肠后的线虫捕食能力降低了 17%。本研究揭示了绵羊胃肠道每个节段对该菌株真菌完整性的个体体外影响，这些条件影响其活力和线虫捕食能力。可以设计输送系统来保护厚垣孢子，考虑到每个胃肠道节段的影响。
