Application Of Pig Manure Compost With Different Biochar Modifies The Antibiotic Resistome In Soil As Shown In Chinese Cabbage Agriculture

Residual antibiotics in fecal sources and the induced antibiotic resistance genes(ARGs)spread in the soil-vegetable system,which can threaten human health through the food chain.Whether the antibiotics/ARGs in pig manurethe can be reduced by current composting additives,or the environmental behavior of manure-derived antibiotics/ARGs in the soilvegetable system is still unclear.In this thesis,through different biochar-pig manure composite composting and indoor pot experiment(Suzhou,Brassica chinensis L),the migration and diffusion mechanism of manure-derived antibiotics / ARGs at different interfaces of the soil-vegetable system were studied,which were introduced through pig manure composting.The main research conclusions of the thesis are as follows:(1)Through three different biomass sources of biochar(herbaceous,woody,animal biomass)-pig manure composite composting experiment,the concentration of antibiotics in the pile at different stages(1,7,15,45,60 d)and the abundance of ARGs as an indicator,the impact of different biochar on the degradation of antibiotics / ARGs in compost were characterized,and the adsorption mechanism of biochar from multiple aspects(element composition,specific surface area and pore structure)were revealed.The results showed that woody biochar had the best specific surface area and pore structure,and was the most effective for the removal of antibiotics / ARGs.Herbaceous biochar and animal biomass biochar were selective for the removal of antibiotics / ARGs.(2)The compost was applied to the soil and planted in the vegetable(Suzhou,Brassica chinensis L).Taking the abundance of ARGs in different interfaces(bulk soil,rhizosphere soil,root endophytes,phyllospheres)as an indicator,the differences of distribution and transfer of ARGs in the soil-vegetable system with different biochar pig manure composts were discussed.The results showed that the detection values of enzyme inactivation genes(tet X),sul1 and sul2 were the highest in the phyllospheres of vegetables among the treatments,and they were the dominant genes in the soil-vegetable system.The detection amount of sul1 in the root endophytes of vegetables in the woody biochar treatment was the highest,and the detection amount of qnr S in the phyllospheres of vegetables in the herbaceous biochar treatment was the highest.The pump efflux gene(tet G)was abundant in the woody biochar treatment.The degree is significantly lower than herbaceous biochar treatment and animal biomass biochar treatment.(3)Through 16 S r RNA high-throughput sequencing,the influence of bacterial community succession on ARGs in the soil were further explored,and the potential host bacteria of ARGs were clarified.Through redundant analysis,it is found that Cyanobacteria,Proteobacteria,and Bacteroidetes are the main factors affecting the changes of ARGs in the soil.The main driving bacteria were inhibited effectively in herbaceous biochar treatment and woody biochar treatment.Network analysis showed that some key functional microorganisms(Proteobacteria,Bacteroidetes,Actinomycetes)may be the main potential host bacteria for ARGs in rhizosphere soil,including 6 potential pathogenic bacteria.Among them,the detection amount of pathogenic bacteria was the lowest in the woody biochar treatment.In summary: Among the three biochars from different biomass sources,antibiotics/ARGs and potential human pathogens can be reduced effectively by woody biochar,which is a better composting additive.