Analysis of Bacterial Community Characteristics, Abundance of Antibiotics and Antibiotic Resistance Genes Along a Pollution Gradient of Ba River in Xi’an, China

Abstract

The microbial communities in freshwater have raised concerns about the ecosystem and human health. Many ecological environmental problems have been found in urban river because of the unreasonable use and long-term wastewater discharge. In this study, we explored the bacterial community composition, abundance of 14 antibiotics and 21 antibiotic resistance genes (ARGs), and water environment features in seven water samples and seven sediment samples from Ba River in Xi’an, China. Results showed Proteobacteria and Bacteroidetes were the dominant phyla in all samples, and sediment samples had a higher bacterial diversity and richness than it in water. Bacterial communities of site 5 and 6 were clustered in discrepant patterns compared to those at remaining sites from other samples. It might be influenced by nutrients, heavy metals and antibiotics. Antibiotics concentrations ranged from 1.26 to 1.61 × 103 ng L-1 in water samples and 1.55 to 4.05 × 102 μg kg-1 in sediment samples. Sulfamerazine (SM1) and erythromycin (ERY) were the chief antibiotics in water samples, while the level of oxytetracycline (OTC) and cefazolin (CFZ) were higher in sediment samples. Canonical correspondence analysis showed that trimethoprim (TMP) was significantly related to Acinetobacter in W6, and that SM1 and OTC had positive correlation with Arcobacter in W5. The tetC, blaTEM, ermF and sul1 had higher pollution abundance ranging from 10-4 to 100 copies/16S rRNA gene copies in all samples. Significant correlations were observed between ARGs and matching antibiotics, suggesting that antibiotics can pose the selective pressure on ARGs in this river. In summary, these finding might provide some new data to the limited information available on the bacterial community characteristics, abundance of antibiotics and ARGs in urban river of China.

Contrasting community assembly processes structure lotic bacteria metacommunities along the river continuum

“…It is worth noting that the sediment community features a unique phylum WS3, also known as the candidate phylum ‘ Latescibacteria ’. This is consistent with previous studies on freshwater sediment (Morrison et al ., 2017; Guan et al ., 2018). Another study derived from single‐cell amplified genomes of WS3 indicates their heterotrophic and strictly fermentative lifestyle and suggested that it may play a crucial role in the turnover of algal detritus (Farag et al ., 2017).…”

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 , ...…”

“…As seen in Figure 4 A, natural waters presented a higher abundance of Firmicutes (22%) and Bacteroidetes (20%), while in artificial waters, Bacteroidetes (25%), Firmicutes (21%) and α-Proteobacateria (22%) were the most representative. The predominance of these phyla was to be expected since they are widely distributed in the environment, including in the intestinal tracts of humans and animals, and in soil, sediments and water [ 3 , 12 , 18 , 24 , 27 , 29 ].…”

“…Concerning types of ARGs in natural water, there is a predominance of bla genes in Africa, Latin America and Europe, with 100%, 45% and 40%, respectively [ 11 , 13 , 14 , 15 , 16 , 21 , 22 , 24 , 25 , 29 , 46 , 47 , 49 , 50 , 59 , 67 , 68 , 69 , 78 ] ( Figure 5 ). In Asian countries, tet genes are reported more frequently (≈15%) [ 14 , 16 , 18 , 70 , 71 ]. In North America, only one study reported the presence of acr genes (21%) [ 12 ].…”

“…Guan et al [ 18 ] reported that the absolute abundance of ARGs ( tetC, bla TEM , ermF, sul1, cmlA and gyrA ) in sediments in some rivers in China was 1 to 3 orders of magnitude higher than in the surface water. In the bacterial community of sediments, the relative abundances of Acidobacteria , Chloroflexi , Spirochaetes , Chlamydiae and Aminicenantes were higher than 1%, while in surface water the percentage was less than 1%, sediments being an environment with greater diversity and bacterial richness.…”