The study investigated the pollution characteristics of MCR-1and MCR-1hosting bacteria in a municipal wastewater treatment plant in Nanjing, China. Their distribution and influence factors, as well as antibiotic resistance characteristics, were comprehensively assessed. The results indicated that the MCR-1abundance decreased obviously along with the treatment process, with the reduction efficiency of 83.6%. However, its relative abundance increased significantly in the treated effluent. High amount of MCR-1was detected in biosolids, with concentration of up to 2.88×1012 copies/L. On the other hand, the concentration of colistin resistant bacteria also decreased gradually along with the treatment process. Their concentration decreased to 53 CFU/mL in the final effluent, with the reduction efficiency of 99.98%, but up to 2.04×105 CFU/mL were detected in biosolids. According to the correlation analysis, MCR-1abundance positively correlated with ammonia concentration, while the relative abundance of MCR-1showed negative correlation with COD, TN and NO3--N concentration. The antibiotic resistance characteristics analysis indicated that MCR-1hosting bacteria in the activated sludge system (CAST and MSBR) and aeration biological fluid tank (ABFT) were tolerant to significantly higher colistin concentration relative to other sites. Additionally, the level of MCR-1hosting bacteria tolerant to colistin was enhanced by the treatment process, which implied that the wastewater treatment process could not completely reduce MCR-1 and MCR-1hosting bacteria, and even lead to the increase of their potential risks. The study will provide implications for assessing the environmental risks of MCR-1represented super antibiotic resistant genes.
Shi P, Jia S, Zhang X X, et al. Metagenomic insights into chlorination effects on microbial antibiotic resistance in drinking water[J]. Water Research, 2013,47(1):111-120.
Jiang X B, Shi L. Distribution of tetracycline and trimethoprim/sulfamethoxazole resistance genes in aerobic bacteria isolated from cooked meat products in Guangzhou, China[J]. Food Control, 2013,30(1):30-34.
[5]
Pal C, Bengtsson-Palme J, Kristiansson E, et al. The structure and diversity of human, animal and environmental resistomes[J]. Microbiome, 2016,4(1):54.
Zhang X X, Zhang T, Occurrence, Abundance,and Diversity of Tetracycline Resistance Genes in 15Sewage Treatment Plants across China and Other Global Locations[J]. Environmental Science & Technology, 2011,45(7):2598-2604.
[8]
Yuan Q B, Guo M T, Yang J. Monitoring and assessing the impact of wastewater treatment on release of both antibiotic-resistant bacteria and their typical genes in a Chinese municipal wastewater treatment plant[J]. Environmental Science:Processes & Impacts, 2014,16(8):1930-1937.
Guo M T, Yuan Q B, Yang J. Insights into the amplification of bacterial resistance to erythromycin in activated sludge[J]. Chemosphere, 2015,136:79-85.
[11]
Liu Y Y, Wang Y, Walsh T R, et al. Emergence of plasmid-mediated colistin resistance mechanism MCR-1in animals and human beings in China:a microbiological and molecular biological study. National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals[J]. Lancet Infectious Diseases, 2016,16(2):161-168.
[12]
Zhi C, Lv L, Yu LF, Doi Y, et al. Dissemination of the mcr-1colistin resistance gene[J]. Lancet Infectious Diseases, 2016, 16(3):292-293.
[13]
Arcilla M S, van Hattem J M, Matamoros S, et al. Dissemination of the mcr-1colistin resistance gene[J]. Lancet Infectious Diseases, 2016,16(2):147-149.
[14]
Veldman K, van Essen-Zandbergen A, Rapallini M, et al. Location of colistin resistance gene mcr-1in Enterobacteriaceae from livestock and meat[J]. Journal of Antimicrobial Chemotherapy, 2016,71(2):2340-2342.
[15]
The White House Office of the Press Secretary. FACT SHEET:Obama Administration Releases National Action Plan to Com bat Antibiotic-Resistant, Bacteria,[EB/OL]. https://www.whitehouse.gov/the-press-office/2015/03/27/fact-sheet-obama-administrationreleases-national-action-plan-combat-ant.
[16]
GB 11914-1989水质化学需氧量的测定[S].
[17]
HJ 535-2009水质氨氮的测定[S].
[18]
GB11894-89水质总氮的测定[S].
[19]
HJ/T346-2007水质硝酸盐氮的测定[S].
[20]
GB 7493-1987水质亚硝酸盐氮的测定[S].
[21]
Bontron S, oirel L, Nordmann P. Real-time PCR for detection of plasmid-mediated polymyxin resistance (mcr-1) from cultured bacteria and stools[J]. Journal of Antimicrobial Chemotherapy, 2016,71(8):2318-2320.
[22]
Matos M, Pereira M A, Parpot P, et al. Influence of tetracycline on the microbial community composition and activity of nitrifying biofilms[J]. Chemosphere.2014,117(8):295-302.
[23]
Dan A, Yang Y, Dai Y N, et al. Removal of antibiotics from sewage plant effluent by a natural biological aerated filter and the influencing factors[J]. Ecological Science, 2012,31(3):289-294.
[24]
Munir M, Wong K, Xagoraraki I. Release of antibiotic resistant bacteria and genes in the effluent and biosolids of five wastewater utilities in Michigan[J]. Water Research, 2011,45(2):681-693.
[25]
He J B, Hu A Y, Chen M, et al. Studies on the pollution levels of antibiotic resistance genes in Jiulong River estuary and wastewater treatment plants in Xiamen[J]. Microbiology, 2012, 39(5):683-695.
[26]
Riesenfeld C S, Goodman R M, Handelsman J. Uncultured soil bacteria are a reservoir of new antibiotic resistance genes[J]. Environmental Microbiology, 2004,6(9):981-989.
