Metagenomic Profiles of Antibiotic Resistance Genes in Activated Sludge, Dewatered Sludge and Bioaerosols

Abstract

Wastewater treatment plants (WWTPs) have been considered hotspots for the development and dissemination of antibiotic resistance in the environment. Although researchers have reported a significant increase in bioaerosols in WWTPs, the associated bacterial taxa, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) remain relatively unknown. In this study, we have investigated the abundance and occurrences of ARGs and MGEs, as well as the bacterial community compositions in activated sludge (AS), dewatered sludge (DS) and bioaerosols (BA) in a WWTP. In total, 153 ARG subtypes belonging to 19 ARG types were identified by the broad scanning of metagenomic profiles obtained using Illumina HiSeq. The results indicated that the total occurrences and abundances of ARGs in AS and DS samples were significantly higher than those in BA samples (p < 0.05). However, some specific ARG types related to sulfonamide, tetracycline, macrolide resistance were present in relatively high abundance in BA samples. Similar to many other full-scale WWTPs, the Proteobacteria (58%) and Bacteroidetes (18%) phyla were dominant in the AS and DS samples, while the Firmicutes (25%) and Actinobacteria (20%) phyla were the most dominant in the BA samples. Although the abundance of genes related to plasmids and integrons in bioaerosols were two to five times less than those in AS and DS samples, different types of MGEs were observed in BA samples. These results suggest that comprehensive analyses of resistomes in BA are required to better understand the emergence of both ARGs and MGEs in the wastewater treatment process due to the significant increase of scientific attention toward bioaerosols effects.

Structure of Bacterial Community with Resistance to Antibiotics in Aquatic Environments. A Systematic Review

“…Of these, there were 128 duplicates, and 16,013 were excluded on the basis of title and abstract screening. A total of 68 studies [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , ...…”

“…These bacteria are abundant in WWTPs in cities in Portugal, Spain, Germany, Sweden, South Korea, and Brazil [ 11 , 41 , 42 , 47 , 48 , 49 , 59 ]. However, they were also determined in treated waters and in natural water systems of marine environments, rivers and lagoons, mainly in Latin American countries [ 34 , 45 , 49 , 50 , 56 , 60 ].…”

“…The majority of ARGs reported are those that confer resistance to β-lactam antibiotics, aminoglycosides, fluoroquinolones and macrolides. However, of the studies, 12 (17.6%) did not have precise information on the types of ARGs found, as is the case for the reports made by Port et al [ 27 ], Han et al [ 48 ], Fang et al [ 51 ], Pan et al [ 54 ], Chen et al [ 55 ], Eduardo-Correia et al [ 57 ], Quintela-Baluja [ 42 ], Clarke et al [ 61 ], Fernandes Cardoso de Oliveira et al [ 62 ], Coutinho et al [ 45 ], Miranda et al [ 63 ], Lu et al [ 64 ], Jiang et al [ 65 ], and Qu et al [ 66 ].…”

“…In Europe, North America and Latin America, the most prevalent ARGs are the bla genes, with approximate prevalence values of 40%, 34% and 89%, respectively [ 11 , 15 , 38 , 40 , 44 , 47 , 59 , 60 , 72 , 76 ]. In Africa, the sul genes (67%) [ 41 ], and in Asia the tet genes, are the most reported (30%) [ 32 , 35 , 48 , 65 , 70 , 71 ] ( Figure 6 ). Most of these genes are reported in WWTPs, which indicates that the processes carried out there must be optimized to reduce the load of ARGs that reaches these plants, especially from products generated from clinical and domestic activities.…”

“…In relation to the reports of bla genes in artificial waters, in North America, bla CTX , bla GES , bla NDM , bla VIM , bla SHV , bla OXA , bla MOX , bla KPC , bla IMP and bla TEM genes were identified in WWTP effluents [ 76 ], and in Europe, the bla VIM gene (12%) was the most prevalent [ 11 , 48 ]. In Asia, a higher abundance of bla TEM (33%) was detected, followed by bla KPC (22%) in water samples from WWTP and aquaculture [ 36 , 38 , 73 ], while in Latin American countries, bla CTX (25%) and bla TEM (25%) were the most prevalent [ 15 , 43 , 44 , 61 ].…”