果蝇共生菌降低有害真菌的毒性

【背景】目前对于如何解决有害真菌对黑腹果蝇的致死性病理研究较少,对共生菌抑制有害真菌的研究引起普遍关注。【目的】检测黑腹果蝇共生菌对病原性真菌的拮抗作用,揭示共生菌提高果蝇的适合度。【方法】利用PDA培养基分离黑腹果蝇食物中真菌;利用形态和rDNAITS基因序列比对进行真菌的鉴定;通过测量菌落直径、孢子数量以及菌丝分枝数量以评定真菌的生长;利用存活率评估病原真菌的毒性;建立无菌和悉生模型,通过发育历期验证其共生菌与病原性真菌的竞争作用;利用双向选择食物装置检测共生菌抑制病原真菌的效果。【结果】从果蝇食物中分离出的真菌经鉴定为拟茎点霉(Phomopsis),可显著地降低成年果蝇的存活率和延缓果蝇发育。东方醋酸杆菌在体外可明显抑制拟茎点霉的生长,有效地减轻拟茎点霉对果蝇的致死作用,挽救了拟茎点霉导致的果蝇发育延滞,改善了果蝇产卵对拟茎点霉的趋避作用。【结论】拟茎点霉是果蝇的一株条件性病原真菌,而东方醋酸杆菌可以有效地减轻拟茎点霉对果蝇生长发育和存活率的损害,从而提高果蝇适合度。

Drosophila symbionts attenuate the pathogenicity of fungi

Background] At present, there are few studies on how to solve the lethal pathogenicity of harmful fungi to Drosophila melanogaster. The intestinal symbiotic bacteria of Drosophila are one of the current research hotspots, and the study on the interaction between symbiotic bacteria and harmful fungi has attracted widespread attention. Objective] To assess the competitive interaction between Drosophila symbionts and pathogenic fungi, consequently mitigating the toxicity of fungi to their hosts. Methods] Fungi were isolated from fly food using PDA medium. The interaction between Drosophila symbionts and pathogenic fungi was examined by means of colony diameter, the number of spores and mycelium branches. The pathogenicity of fungi was examined using Drosophila infection. The germ-free and gnotobiotic flies were established to verify the protection of Drosophila symbionts against fungi. The 2-choice egg-laying apparatus was employed to assay the oviposition selection of D. melanogaster female adults. Results] A fungus was identified as Phomopsis FY that was detrimental to the survival and development of Drosophila upon infection. Acetobacter orientalis hindered the growth of Phomopsis FY in vitro, and decreased the mortality rate of Phomopsis FY-infected flies in vivo, consequently mitigating the toxicity of Phomopsis FY to the hosts. Additionally, the presence of A. orientalis overrode the avoidance of oviposition on Phomopsis FY-associated substrates. Conclusion] Phomopsis FY was identified as a conditionally potential Drosophila pathogen. Commensal A. orientalis mitigated the susceptibility of Drosophila to pathogenic fungi, providing insight into the natural interplay between commensal and pathogenic microbial communities that contribute to animal health and pathogenesis.