| Antibiotic resistance gene contamination has become a global environmental problem,which can be transferred from non-pathogenic bacteria and cells to pathogenic bacteria and cells through a variety of transmission methods,thereby increasing the risk of human pathogenic bacteria infection.There are a lot of ARGs and ARBs in the sewage treatment system,which is a good place for value-added and diffusion of ARGs and ARBs.Organic substances such as fungicides,surfactants and antibiotics can lead to common or cross-resistance of bacteria in water and promote the spread of ARGs.Pharmaceutical wastewater mainly includes antibiotic production wastewater,synthetic drug production wastewater,Chinese patent medicine production wastewater,washing water and washing wastewater in the production process of various preparations.Pharmaceutical wastewater is an important source of antibiotic resistance gene amplification and dissemination because of its complex composition,many kinds of organic pollutants,high concentration,high toxicity,deep color and high salt content.In this study,fluorescence quantitative PCR and 16S rRNA gene sequencing techniques were used to study the changes of ARGs and ARBs in different treatment systems in the same city with the technological process and the differences of ARGs distribution in different systems.The structure characteristics of microbial communities were analyzed to explore the relationship between microbial community structure and ARGs.The research results are as follows:1)In cephalosporin pharmaceutical wastewater treatment plants,the detection frequencies of beta-lactam resistance genes OXA-1,OXA-2 and OXA-10 were 100%at each stage of wastewater treatment.Instead of reducing the abundance of OXA-1 and OXA-2,the two-stage aeration process stimulated the amplification of OXA-1 and OXA-2,which was an important source of pollution for some resistance genes.The two-stage aeration treatment system had a better removal effect on the resistance genes of beta-lactam OXA-10.The detection frequencies of sul1,sul2,tetO,tetQ,tetW,OXA-1 and the movable genetic element Int1 were all 100%in the mixed antibiotic pharmaceutical wastewater treatment plant.From anaerobic tank to sedimentation tank,the total resistance gene concentration ranged from 3.09×10~8 to 2.26×10~9 copies/g(dry/weight),and the total gene concentration increased by 7.3 times.Resistance genes OXA-1,sul 1 and sul2 were found to be more resistant to antibiotics than tetracyclines such as tetO,tetQ and tetW.2)The main dominant phylum in cephalosporin pharmaceutical wastewater treatment plants and the dominant phylum in sewage treatment plants are similar in species,namely Proteobacteria,Planctomycetes,Bacteroidetes,Chloroflexi,Acidobacteria,and the average total relative abundance.The proportion accounts for 82.13%.Proteobacteria,Bacteroidetes,Firmicutes,Thermus and Gemmatimonadetes were the dominant phylum in the mixed antibiotic pharmaceutical wastewater treatment plant.The average relative abundance ratio was 81.05%.3)The results of fluorescence quantitative PCR and high throughput sequencing showed that Comamonadaceae,Thauera and Metyloversatilis might be the main genera of OXA-1 resistant genes in microbial communities,and Dokdonella might be the main genera of OXA-2 resistant genes.Bacterium,Aeromicrobium,Bdellovibrio,Gemmatimonadaceae were positively correlated with sul1,which was the main bacterial genus of sul1 in the microbial community;Acinetobacter,Brachymonas and Caldimonas were positively correlated with tetO and tetW,which might be the main bacterial genus of tetO and tetW in the microbial community.In this study,the characteristics of microbial community structure in activated sludge of pharmaceutical wastewater and the transmission pathway and interaction of antibiotic resistance genes were revealed by Miseq sequencing and fluorescence quantitative polymerase chain reaction in two pharmaceutical wastewater from different antibiotic factories,providing parameters for biological treatment of pharmaceutical wastewater.It also provides a theoretical basis for the formulation of effective ARGs(antibiotic resistance genes)environmental pollution control methods. |
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