Corporación Colombiana de Investigación Agropecuaria AGROSAVIA, Sede Central, Mosquera, Colombia.
Universidad Nacional de Colombia., Sede Bogotá, Bogotá, Colombia.
Vet Res Commun. 2023 Sep;47(3):1405-1412. doi: 10.1007/s11259-023-10089-y. Epub 2023 Apr 3.
Duddingtonia flagrans is a nematophagous fungus employed as a biocontrol agent of gastrointestinal nematodes in ruminants. After oral ingestion and passage through the digestive tract of animals, this microorganism captures the nematodes in the feces. The drastic conditions of ruminant digestive tract could affect fungi chlamydospores and therefore biocontrol activity. The aim of this study was to evaluate in vitro the effect of four ruminant digestive segments on the concentration and nematode predatory ability of a Colombian native strain of D. flagrans. The sequential four-step methodology proposed evaluated conditions of the oral cavity, rumen, abomasum, and small intestine such as pH (2, 6, 8), enzymes (pepsin, pancreatin), temperature (39 °C), and anaerobiosis comparing short (7 h) and long (51 h) exposure times. The results showed that the nematode predatory ability of the fungi is affected by sequential exposure to gastrointestinal segments and this effect depends on the exposure time to those conditions. After short exposure (7 h) through the four ruminant digestive segments, the fungi had a nematode predatory ability of 62%, in contrast, after long exposure (51 h) the nematode predatory ability was lost (0%). Moreover, the number of broken chlamydospores was higher in the long-exposure assay.
多粘类芽孢杆菌是一种寄生性真菌，被用作反刍动物胃肠道线虫的生物防治剂。这种微生物经口服摄入并通过动物的消化道后，会在粪便中捕获线虫。反刍动物消化道的恶劣条件可能会影响真菌厚垣孢子，从而影响生物防治活性。本研究的目的是评估四个反刍动物消化段对哥伦比亚本土多粘类芽孢杆菌菌株浓度和线虫捕食能力的体外影响。所提出的四步连续方法评估了口腔、瘤胃、皱胃和小肠的条件，如 pH 值（2、6、8）、酶（胃蛋白酶、胰酶）、温度（39°C）和厌氧条件，并比较了短时间（7 小时）和长时间（51 小时）暴露的情况。结果表明，真菌的线虫捕食能力受到连续暴露于胃肠道段的影响，这种影响取决于暴露于这些条件的时间。经过四个反刍动物消化段的短时间（7 小时）暴露后，真菌对线虫的捕食能力为 62%，而长时间（51 小时）暴露后，捕食能力丧失（0%）。此外，长时暴露试验中厚垣孢子的破裂数量更高。
