Lin Chenshuo, Li Li-Juan, Yang Kai, Xu Jia-Yang, Fan Xiao-Ting, Chen Qing-Lin, Zhu Yong-Guan
State Key Laboratory for Ecological Security of Regions and Cities, Ningbo Urban Environment Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China.
Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China.
ISME J. 2025 Jan 2;19(1). doi: 10.1093/ismejo/wraf009.
Protozoa, as primary predators of soil bacteria, represent an overlooked natural driver in the dissemination of antibiotic resistance genes (ARGs). However, the effects of protozoan predation on ARGs dissemination at the community level, along with the underlying mechanisms, remain unclear. Here we used fluorescence-activated cell sorting, qPCR, combined with metagenomics and reverse transcription quantitative PCR, to unveil how protozoa (Colpoda steinii and Acanthamoeba castellanii) influence the plasmid-mediated transfer of ARGs to soil microbial communities. Protozoan predation reduced the absolute abundance of plasmids but promoted the expression of conjugation-associated genes, leading to a 5-fold and 4.5-fold increase in conjugation frequency in the presence of C. steinii and A. castellanii, respectively. Excessive oxidative stress, increased membrane permeability, and the provoked SOS response closely associated with the increased conjugative transfer. Protozoan predation also altered the plasmid host range and selected for specific transconjugant taxa along with ARGs and virulence factors carried by transconjugant communities. This study underscores the role of protozoa in the plasmid-mediated conjugative transfer of ARGs, providing new insights into microbial mechanisms that drive the dissemination of environmental antibiotic resistance.
原生动物作为土壤细菌的主要捕食者，是抗生素抗性基因（ARGs）传播中一个被忽视的自然驱动因素。然而，原生动物捕食对群落水平上ARGs传播的影响及其潜在机制仍不清楚。在此，我们使用荧光激活细胞分选、定量PCR，并结合宏基因组学和逆转录定量PCR，来揭示原生动物（斯坦氏肾形虫和卡氏棘阿米巴）如何影响ARGs向土壤微生物群落的质粒介导转移。原生动物捕食降低了质粒的绝对丰度，但促进了接合相关基因的表达，导致在存在斯坦氏肾形虫和卡氏棘阿米巴的情况下，接合频率分别增加了5倍和4.5倍。过度的氧化应激、增加的膜通透性以及引发的SOS反应与接合转移增加密切相关。原生动物捕食还改变了质粒宿主范围，并选择了特定的接合子分类群以及接合子群落携带的ARGs和毒力因子。本研究强调了原生动物在ARGs质粒介导的接合转移中的作用，为驱动环境抗生素抗性传播的微生物机制提供了新的见解。
