Reducing Antibiotic Resistance Genes Of Agricultural Waste During Composting Of Aerobic Combined With Anaerobic

With the development of large-scale and industrialization agriculture,the agricultural wastes are dominated by livestock manure and crop straw with an increasing number.If the agricultural wastes are disposed improperly,not only cannot mitigate the burden on the environment,but also cause secondary pollution to the environment.In light of this,livestock manure and crop straw were chosen to be the subjects of this study.A number of studies have demonstrated antibiotic and antibiotic resistance gene（ARGs）residual were generally high in livestock manure.The application of the livestock manure to farm soil as fertilizer,which causes serious threat to farmland environmental health and crop safety.Especially,the spreads antibiotic resistance genes among bacteria by horizontal gene transfer,which was a new class of gene pollutants.There was not only polluting farmland soil,but also posing a huge threat to human health by entering the human body via food-chain enrichment.Thus,ARGs abatement in livestock manure is an essential prerequisite for safe the valorization of the agricultural waste.However,numerous studies have demonstrated that the capacity of aerobic composting or anaerobic composting process reduce the abundance of ARGs generally suffer from low efficiency,and at a certain risk of ARGs proliferation.There is,therefore,an urgent need to optimize the composting process,which could reduce the abundance of ARGs.While for the composting process of aerobic combined with anaerobic,there are no specific research about it so far.Thus,in this paper,the composting process of aerobic combined with anaerobic was optimized as a subject of study.Firstly,the aim of the present study was to screen out the optimal parameter combinations of the quality of compost products based on guaranting nutrition and safety.In the following experiment,the optimal parameter combinations was used as control group（CK）.And study the dynamic change of ARGs and relationshio among ARG,microbial community and environmengtal factors in single-factor experiments which had five parameters,included material ratio,combined anaerobic composting time,stirring frequency and microbial agent.The aim of this study was to identify the impact of crucial factors on change of ARGs abundance and optimize composting process there by improving the reduction effect of ARGs.The main results were as follows:（1）The consideration of ARGs abatement simultaneously with ensuring the quality of compost products.First,the aim of the present study was to screen out the optimal parameter combinations of the quality of compost products based on guaranting nutrition and safety.The composting process of aerobic combined with anaerobic was optimized using orthogonal Latin squares experiment design.Experimental results showed that the optimal processing parameters combination of the quality of compost products was A₂B₃C₂D₂,which was obtained by analysis of variance and picture of index-factor.The A₂B₃C₂D₂ was able to fulfill reduce the content of TOC losses while ensuring composting germination index greater than 80%.That is,when the composting process of aerobic combined with anaerobic parameters combination was 3:1 the material ratio of manure to straw,6 d combined anaerobic composting time,1 time/d stirring frequency and Jin Baobei microbial agent,the quality of compost products was better.（2）The composting process of aerobic combined with anaerobic under different treatment condition,the optimal processing parameters combination of reduction effect of ARGs abundance was CK group,which was in line with the optimal processing parameters combination of the quality of compost products.When the composting process of aerobic combined with anaerobic parameters combination was 3:1 the material ratio of manure to straw,6 d combined anaerobic composting time,1time/d stirring frequency and Jin Baobei microbial agent,the average reduction efficiency of ARGs abundance was achieved with 97.56%after composting.Among these,ermF had the highest reduction efficiency which can reach 99.78%.This result achieved the goal for this study that ensure optimize the reduction effect of composting on ARGs based on the quality of compost products.（3）The composting process of aerobic combined with anaerobic under different treatment condition,the optimal processing parameters combination of reduction effect of ARGs host bacteria abundance and inhibited it proliferation ability was CK.After composting,the average reduction efficiency of ARGs host bacteria abundance was achieved with 72.69%.Results of Principal Component Analysis（PCA）and Procrustes analysis demonstrated that the changes in ARGs were remarkable affected by the succession of microorganisms.Redundancy analysis（RDA）showed that the microbial community structure accounted for 90.3%of the total factors in the change of ARGs quantified in this research.Among the dominant microbial taxa,Ureibacillus,Petrimonas,Truepera,Pseudomonas were main genus influencing ARGs abundance change.（4）The composting process of aerobic combined with anaerobic under different treatment condition,the optimal processing parameters combination of the quality of compost products was CK as well,and this result further verified conclusion one.The Redundancy analysis（RDA）results indicated that environmental factors explained 57.20%of the total variation in change of ARGs abundance.And TOC,pH,C/N,NH₃-N and temperature were crucial environmental factor influencing ARGs abundance change.