Microbial Contamination Of Soil By Doxycycline And Pentachlorophenol Study On Degradation Mechanism

The widespread use of veterinary antibiotics and organochlorine pesticides in the soil environment has always been a hot spot in ecological research,but the interaction between the two in the soil is still rarely reported.In this paper,Doxycycline(DOX)and Pentachlorophenol(PCP)were used as targets to study the effects of veterinary antibiotics and organochlorine pesticides on their degradation efficiency,as well as the amount of soil microflora and community structure.The study of the main functional microbial activity revealed the microbiological mechanism of interaction between soil veterinary antibiotics and organochlorine pesticides.To provide a solution to the combined pollution control of veterinary antibiotics and organochlorine pesticides,provide theoretical basis and data support.In this paper,three DOX concentrations(0,4.8 and 12.8 mg/kg)and three PCP concentrations(0,6.4,and 10.7 mg/kg)were set.A total of 10 treatments,blank soil group(CK),blank soil + blank pig manure group(A0),low DOX group(A1),low DOX low PCP group(A1B1),low DOX high PCP group(A1B2),high DOX Group(A2),high DOX low PCP group(A2B1),high DOX high PCP group(A2B2),low PCP group(B1),high PCP group(B2),with 3 replicates per treatment.Samples were taken at 0,1,3,5,8,13,18,24,and 45 days.High-performance liquid chromatography,real-time PCR,and 16 s rRNA sequencing techniques were used to determine the concentration of doxycycline and pentachlorophenol in the soil.The effects of PCP on the degradation of PCP by DOX and DOX were studied and the microbiological mechanism was studied in terms of the basic physical and chemical properties,soil bacterial count,tetracycline resistance gene content,bacterial community structure and enzyme activity.The main findings are as follows:(1)When the initial DOX concentration was 4.8 mg/kg,the half-lives of DOX degradation in A1,A1B1,and A1B2 groups were 20.92 d,21.41 d,and 23.97 d,respectively.High initial PCP concentrations significantly inhibited DOX degradation(P<0.05);The initial DOX concentration was 12.8 mg/kg.The half-lives of DOX degradation in A2,A2B1 and A2B2 groups were 23.64 d,24.74 d and 27.41 d,respectively.High initial PCP concentrations also significantly inhibited DOX degradation(P<0.05).(2)High concentrations of PCP residues significantly inhibited bacterial counts and urease activity(P<0.05),reduced Porphyromonadaceae and Lactobac illus,increased Sphingomonas genus and The relative abundance of Bacillus.(3)The high initial PCP concentration significantly reduced the contents of tet A,tet M,tet Q and tet X,and the low initial PCP concentration significantly decreased the tet Q content(P<0.05).PCP residue had no significant effect on soil pH,electrical conductivity,total nitrogen,and organic matter(P>0.05).(4)When the initial PCP concentration was 6.4 mg/kg,the PCP degradation half-lives in the B1,A1B1 and A2B1 groups were 11.03 d,11.41 d and 13.61 d,and high DOX residues significantly inhibited the degradation of soil PCP(P<0.05).When the initial PCP concentration was 10.7 mg/kg,the PCP degradation half-lives in the B2,A1B2,and A2B2 groups were 12.07 d,11.46 d,and 14.11 d,and high DOX residues also significantly inhibited soil PCP degradation(P<0.05).(5)DOX residue significantly increased the number of soil bacteria and urease,catalase activity(P<0.05),increased pH,electrical conductivity,and total nitrogen and organic carbon content(P<0.05),high concentrations of doxycycline residues reduced soil The relative abundance of Sphingomonas.In summary,in this experiment,the high initial PCP concentration may be by inhibiting the number of bacteria,changing the microbial community and activity to inhibit the microbial degradation of doxycycline,while the number of resistance genes also decreases,and the high initial DOX concentration may be to inhibit the microorganism of pentachlorophenol by changing the microbial community structure Degradation process.