Turning pig manure into biochar can effectively mitigate antibiotic resistance genes as organic fertilizer

Antibiotic resistance genes (ARGs) existing in livestock and poultry manure have the risk to spread and proliferate. This might endanger people’s health. The common treatment of livestock and poultry manure is anaerobic digestion. But the change of ARGs during anaerobic digestion require further study, and the effect of digestate fertilization to the antibiotic resistance of cropland soil is still unclear. This study investigated the pig manure, biogas liquid, biogas residue, and cropland soils fertilized with and without digestate. The results showed that, the relative abundance of ARGs in biogas residue was much higher than other samples. The average relative abundance was 1.46×10-1 copy ratio (copy of ARG/copy of 16S rRNA gene), and the total relative abundance was 3.07 copy ratio. There were 21 ARGs detected in the 5 samples. 11 of them were shared by the 5 samples. The main ARGs were aminoglycoside, chloramphenicol, sulfonamide, tetracycline, and multidrug. Aminoglycoside had the highest relative abundance, and the total relative abundance in all samples was 1.18 copy ratio. Anaerobic digestion increased the total relative abundance of ARGs in pig manure from 1.14×10-1 to 1.70×10-1 copy ratio. Fertilization of digestate increased the total relative abundance of AGRs in soil from 3.27×10-1 to 7.29×10-1 copy ratio.

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Antibiotic Resistance Genes in Different Animal Manure and their Derived Organic Fertilizer

10.21203/rs.3.rs-29643/v1 ◽

2020 ◽

Author(s):

Yan Xu ◽

Houyu Li ◽

Rongguang Shi ◽

Jiapei Lv ◽

Bihan Li ◽

...

Keyword(s):

Antibiotic Resistance ◽

Resistance Genes ◽

Pathogenic Bacteria ◽

Bacterial Resistance ◽

Organic Fertilizer ◽

Poultry Manure ◽

Antibiotic Resistance Genes ◽

Animal Manure ◽

Procrustes Analysis ◽

Organic Fertilizers

Abstract Background: The prevalence of antibiotic resistance genes (ARGs) in animal manure poses threats to the environmental safety. Organic fertilizers fermented by livestock and poultry manure are directly applied to farmland, which would cause the potential outbreak of bacterial resistance in agricultural environment. This study investigated the composition of ARGs in different animal manure and their derived organic fertilizers. Results: Results showed that the abundance of several ARGs, such as sul 2, Tet B-01, Tet G-01 and Tet M-01 in organic fertilizer samples was 12%~96% lower than in animal manure. However, there was an increasing of Tet K and erm C abundance from animal manure to the organic fertilizers. No correlation between ARGs and environmental factors such as pH, TN, antibiotics was observed by Redundancy analysis (RDA). Procrustes analysis revealed the significant correlation between bacterial community structures and the ARGs abundance (r=0.799, p<0.01). Non-metric multidimensional scaling (NMDS) analysis suggested that microorganisms in organic fertilizer may be derived from animal manure. Additional, pathogenic bacteria (especially Actinomadura ) would proliferate rather than decrease from manure to organic fertilizer. Conclusion: Overall, this research suggests that the composting treatment of manure could effectively reduce these ARGs and pathogens,even cause partial ARGs and pathogens proliferation. It also shows that the microorganism might significantly influence ARGs profiles in composting.

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