دانلود رایگان مقاله انگلیسی اثرات کرم های خاکی بر ژن های مقاوم به تتراسایکلین و فلوروکینولون لجن فاضلاب - الزویر 2018

Abstract

 Diverse antibiotic resistance genes (ARGs) present in sewage sludge are difficult to be eliminated using conventional sludge treatment processes. To date, little remains known on the fate of the ARGs during vermicomposting of sludge. This study aimed to investigate the effect of earthworms on the fate of tetracycline and fluoroquinolone resistance genes, and integrons during vermicomposting of sewage sludge through contrasting two systems of sludge stabilization with and without earthworms. Compared to the control without earthworms, vermicomposting significantly (p<0.05) decreased the abundances of tetracycline and fluoroquinolone resistance genes and int1, with complete removal for parC. Variations in ARGs were associated with environmental factors, horizontal gene transfer, bacterial community composition, and earthworms during vermicomposting. In addition, earthworms strongly affected the possible host bacteria encoding ARGs and Int1, abating the pathogenic bacteria in vermicomposting product. These results imply that vermicomposting could effectively reduce tetracycline and fluoroquinolone resistance genes in the sludge.

4. Conclusions

Compared to the control without earthworms, the abundances of tetracycline and fluoroquinolone resistance genes, and class 1 integron were reduced by 19 vermicomposting, with 100% removal for parC. The variations of ARGs were influenced by environmental factors, bacterial community abundance and horizontal gene transfer, notable for the control system. The members of Proteobacteria and Antinobacteria were the potential hosts in vermicomposting. The inoculation of earthworms strongly affected the possible host bacteria encoding ARGs and Int1, decreasing the pathogenic bacteria in vermicomposting product. This study suggests that vermicomposting could be effectively used to lower tetracycline and fluoroquinolone resistance genes of the sludge.