Effects Of Organic Fertilizer Fermented From Antibiotic Residues On Crop Growth And ARGs Risk Evaluation

Antibiotic bacterial residues are solid wastes which produced during producing antibiotics.The bacterial residues will harm the environment and increase the risk of antibiotic resistance genes(ARGs)transmission if it is not handled properly.Composting is one of the economically feasible methods to realize the harmless and resource utilization of bacterial residues.In this study,we did both greenhouse and field experiments with growing tomato and strawberry,to examining the effects of organic fertilizer which prepared with penicillin residues on crop growth,soil nutrients and bacterial community.We also tested if and how diversity and abundance of antibiotic resistance genes were influenced by such organic fertilizer in the soil.We found:1.In greenhouse experiment,bacterial residue organic fertilizer promoted the growth of tomato and strawberry plants compared to plant-derived organic fertilizer.Specifically,organic fertilizer with bacterial residues significantly increased the dry weight of tomato plant both above and below ground,and increased the fresh weight and dry weight of strawberry plant above ground.Field experiments showed that bacterial residue organic fertilizer significantly increased the fresh weight and dry weight of the two crops compared to conventional compound fertilizer,but it did not influence yields of these two crops.Bacterial residue organic fertilizer increased the vitamin C content in tomato fruits,but has no significant effects on the fruit quality of strawberry.In addition,compared to conventional compound fertilizer,bacterial residue organic fertilizer improved the organic matter content of soil in the tomato field,and ammonium nitrogen of soil in strawberry field.2.The high-throughput sequencing results showed that compared to conventional compound fertilizer,bacterial residue organic fertilizer did not change the Shannon index and Chao1 index of the microbial community,suggests that the bacterial residue organic fertilizer did not affect alpha diversity of the microbial community in the soil.In addition,bacterial residue organic fertilizer did not significantly affect the β diversity of the soil microbial community.The bacterial residue organic fertilizer did not change the composition of soil bacterial community at the phylum level,but changed the relative abundance at the phylum level.Comparing to conventional compound fertilizer,bacterial residue organic fertilizer significantly increased the relative abundance of Proteobacteria and Chloroflexus in the soil from tomato field,but significantly reduced the relative abundance of Acidobacteria and Planctomycetes in the soil from strawberry field.3.Integron enzyme genes and five types of antibiotic resistance genes(including β-lactam resistance genes,tetracycline resistance genes,aminoglycoside resistance genes,and large Cyclolactone resistance genes,sulfonamide resistance genes)in antibiotic residue organic fertilizer and its raw materials were quantified by q PCR.The results showed that compared to raw materials,diversity of ARGs and MGEs was not significantly different in bacteria residue organic fertilizer.In addition,there is no significant difference of diversity of ARGs and MGEs between bacterial residue organic fertilizer and plant-derived organic fertilizer.The abundance of aminoglycoside resistance gene aada5,integron enzyme gene cinti-Ⅰ,sulfonamide resistance gene sul(I)and sul(II)in bacterial residue organic fertilizer was significantly higher than in raw material,while the abundance of β-lactam resistance gene bla TEM was significantly lower.4.Compared with no fertilization treatment,the application of fungal residue organic fertilizer significantly increased the diversity of soil ARGs and MGEs species,while compared with plant-based organic fertilizer and conventional compound fertilizer,the application of fungal residue organic fertilizer had no significant effect on the diversity of soil ARGs and MGEs species.Compared with no fertilization and plant-derived organic fertilizer,the absolute abundances of integrase gene cinti-Ⅰ,sulfonamides resistance gene sul(I),macrolide resistance genes erm B and erm F,and aminoglycoside resistance gene aada5 were significantly increased in tomato soil in the greenhouse after the application of fungal residue organic fertilizer.Compared with no fertilization and conventional compound fertilizer,the absolute abundance of integrase gene cinti-Ⅰ,aminoglycoside resistance gene aada1,sulfonamides resistance gene sul(II),tetracycline tet M and tet W resistance genes were significantly increased after the application of fungal residue organic fertilizer in tomato field soil,while other resistance genes had no significant changes.In summary,compared with plant-derived organic fertilizers and conventional compound fertilizers,antibiotic bacterial residue organic fertilizer improved the organic matter content of soil in tomato field and ammonium nitrogen of soil in strawberry field,further can effectively promote the growth of tomato and strawberry.Bacterial residue organic fertilizer did not influence the diversity of soil bacterial communities and the composition of soil bacterial community at the phylum level,but increased the relative abundance of Proteobacteria and reduced the relative abundance of Chlorocurcus in the soil from tomato field as well as Acidobacteria and Planctomycetes in the soil from strawberry field.Transformed bacterial residue to organic fertilizer by composting technology did not change the diversity of antibiotic gene.Bacterial residue organic fertilizer had no impact on the diversity of soil antibiotic resistance genes compared to no fertilization treatment.Compared with no fertilizer treatment,microbial residue organic fertilizer significantly increased the diversity of soil ARGs and MGEs,while there was no significant difference in the diversity of soil ARGs and MGEs compared with plant-based organic fertilizer.Compared with no fertilization and plant-derived organic fertilizer,the absolute abundance of some resistance genes of integrases,sulfonamides,macrolides and aminoglycosides was significantly increased in pot tomato soil after application of organic fertilizer from bacterial residue.Compared with no fertilization and conventional compound fertilizer,the absolute abundance of some resistance genes of integrases,aminoglycosides,aminoglycosides and tetracycline were significantly increased after the application of fungal residue organic fertilizer in tomato field soil,while other resistance genes had no significant changes.Therefore,the risk of antibiotic resistance genes needs to be further evaluated.