两种土著食细菌线虫对五种细菌的取食偏好及相关机制

Feeding Preference of Bacterial-feeding Nematodes to Five Different Bacteria and Its Mechanisms

食细菌线虫通过取食细菌改变土壤微生物的活性和群落结构从而影响土壤生态系统功能,而食细菌线虫取食细菌存在选择偏好。本试验通过设置"自助餐"式平板培养试验,研究了2种土著食细菌线虫(拟丽突属线虫和中杆属线虫)对5种细菌的活菌体、灭活菌体及菌体分泌物的取食偏好,以为进一步揭示土壤生态系统中食细菌线虫与细菌相互作用关系奠定基础。研究结果显示:拟丽突属和中杆属线虫对活菌体的取食偏好基本一致,均对G-菌具有偏好,其偏好顺序为:荧光假单胞菌>大肠杆菌>贪噬菌>解淀粉芽孢杆菌>巨大芽孢杆菌。拟丽突属线虫对5种细菌分泌物的辨识和取食不存在选择性偏好,从而使其对活菌体及灭活菌体的取食偏好顺序基本一致;而中杆属线虫对活菌体及灭活菌体的取食偏好存在显著差异,这可能与中杆属线虫对5种细菌分泌物的辨识和取食具有选择性偏好有关。细菌分泌物对中杆属线虫的取食偏好机制还有待进一步研究。

Bacterial-feeding nematodes can influence the function of soil ecosystems by altering bacterial activity and community structure. There is a feeding preference when bacterial-feeding nematodes confront towards different bacteria. A ＂cafeteria＂ diet experiment was set up to study the feeding behavior of Acrobeloides sp. and Mesorhabditis sp. to the living bacteria, killed bacteria and bacterial secretions of five bacteria in order to help us understand better the interactions between bacterial-feeding nematodes and bacterial community structure in soil ecosystems. The results demonstrated that the feeding preferences of Acrobeloides sp. and Mesorhabditis sp. to five living bacteria were similar. The two nematodes both preferred G-bacteria and the feeding preference order was P. fluorescens〉E. coli 〉Variovorax sp. 〉B. amyloliquefaciens 〉B. megaterium. Acrobeloides sp. did not show preference to the five bacterial secretions which led to the feeding preference of Acrobeloides sp. to living bacteria and killed bacteria were similar. In contrast, there were big differences in feeding preference of Mesorhabditis sp. to living bacteria and killed bacteria, this may be related to the feeding preference of Mesorhabditis sp. to different bacterial secretions. However, the mechanism of bacterial secretions on feeding preference of Mesorhabditis sp. needs further study.