The Influence Of Temperature And Animal Cadaver Pollution On Antibiotic Resistance Genes In The Yellow River Water Based On Metagenomics

Objective: The decomposition of large numbers of corpses in water will cause serious environmental pollution and even threaten public health.However,the influence mechanism of temperature and animal carcass contamination on antibiotic resistance genes(ARGs)in the Yellow River water remains unknown.This study aimed to analyze the abundance and composition of ARGs,the effects of temperature and cadaver pollution on the ARG profiles,the patterns of ARGs with temperature,the key drivers of ARGs in the Yellow River water,and the changing trends of high-risk ARGs and pathogenic related bacteria associated with human diseases after elevated temperature.This provides a scientific theoretical basis for the prediction of pollutants in the Yellow River water.Methods: Using metagenomic sequencing,16S rRNA high-throughput sequencing,and absolute real-time quantitative PCR,this study analyzed the structure,composition,abundance and diversity of ARGs,mobile genetic elements(MGEs)and bacterial communities,the abundance of high-risk ARGs and pathogenic related bacteria associated with human diseases,and their changing trends with temperature between cadaver groups(Yellow River water adding fish cadaver)and control groups(Yellow River water)by indoor temperature gradient experiments at 23,26,29,32,and35℃.Results:(1)Thirty ARG types including 668 subtypes and 28 MGE types including 112 subtypes were detected in 40 collected water samples.(2)Temperature and cadaver decomposition had significant effects on the ARG and MGE profiles as revealed by principal component analysis and permutational multivariate analysis of variance.The ARG abundance was significantly enriched by the corpse decay(P < 0.05).Within the range of 23-35℃,the ARG abundance increased but its diversity decreased with elevated temperature.(3)Null model showed that ARG community assembly was dominated by deterministic process,accounting for 63.32% to 95.08% in the corpse groups.Its deterministic proportion first increased and then decreased with increasing temperature.However,the assembly process of MGEs was dominated by stochasticity under most temperature gradients.(4)In the corpse groups,ARG types resisting carbapenem,dicyclomycin,and diaminopyrimidine antibiotic increased and ARG types resisting aminoglycoside,fusidic acid,and elfamycin antibiotic decreased with temperature significantly,but others(～79%)were temperature insensitive.(5)Based on multiple regression on distance matrices and permutational multivariate analysis of variance,ARG profiles were significantly influenced by temperature,cadaver decomposition,bacterial community,MGEs,and all physicochemical factors except nitrate nitrogen(P < 0.05),with cadaver decomposition having the greatest impact on ARG profiles in the Yellow River water.(6)In the Yellow River water samples contaminated by corpses,21 high-risk ARGs(bacA,mdtA,tetM,etc.)and 22 pathogenic related bacteria(Comamonas,Pseudomonas,Clostridium,etc.)were screened and showed positive network cooccurrence patterns with temperature.Conclusions:(1)ARGs were diverse and abundant in the Yellow River water sample,and the ARG pollution cannot be ignored.(2)The abundance and diversity of ARGs in the Yellow River water vary with water temperature.Within the range of 23-35℃,the ARG abundance increased but its diversity decreased with elevated temperature.(3)The ARG assembly process was mainly deterministic in the Yellow River water contaminated with animal corpses.(4)The abundance of many high-risk ARGs and pathogenic related bacteria associated with human diseases,which may mean greater potential threats to public health.