Limited Bacterial Diversity within a Treatment Plant Receiving Antibiotic-Containing Waste from Bulk Drug Production

Abstract

Biological treatment of waste water from bulk drug production, contaminated with high levels of fluoroquinolone antibiotics, can lead to massive enrichment of antibiotic resistant bacteria, resistance genes and associated mobile elements, as previously shown. Such strong selection may be boosted by the use of activated sludge (AS) technology, where microbes that are able to thrive on the chemicals within the wastewater are reintroduced at an earlier stage of the process to further enhance degradation of incoming chemicals. The microbial community structure within such a treatment plant is, however, largely unclear. In this study, Illumina-based 16S rRNA amplicon sequencing was applied to investigate the bacterial communities of different stages from an Indian treatment plant operated by Patancheru Environment Technology Limited (PETL) in Hyderabad, India. The plant receives waste water with high levels of fluoroquinolones and applies AS technology. A total of 1,019,400 sequences from samples of different stages of the treatment process were analyzed. In total 202, 303, 732, 652, 947 and 864 operational taxonomic units (OTUs) were obtained at 3% distance cutoff in the equilibrator, aeration tanks 1 and 2, settling tank, secondary sludge and old sludge samples from PETL, respectively. Proteobacteria was the most dominant phyla in all samples with Gammaproteobacteria and Betaproteobacteria being the dominant classes. Alcaligenaceae and Pseudomonadaceae, bacterial families from PETL previously reported to be highly multidrug resistant, were the dominant families in aeration tank samples. Despite regular addition of human sewage (approximately 20%) to uphold microbial activity, the bacterial diversity within aeration tanks from PETL was considerably lower than corresponding samples from seven, regular municipal waste water treatment plants. The strong selection pressure from antibiotics present may be one important factor in structuring the microbial community in PETL, which may affect not only resistance promotion but also general efficiency of the waste treatment process.

Diversity of Multidrug-Resistant Bacteria in an Urbanized River: A Case Study of the Potential Risks from Combined Sewage Overflows

“…The diversity of MDR isolates was highest at the upstream site and significantly lower at the CSO site during the overflow event (Figure 5). This is consistent with several prior studies that have documented reduced diversity in environments experiencing wastewater pollution [66][67][68]. In our study, nearly all (97%) isolates were Proteobacteria and Bacteroidetes, which are among the phyla most commonly reported in rivers, tap water, and wastewater [69][70][71].…”

Environmental factors influencing the development and spread of antibiotic resistance

“…The conditions bacteria face within treatment plants treating wastewater from antibiotics production are largely unexplored, but are also likely to be extensively selective, resulting in very limited diversity of bacteria present in such settings (Marathe et al . 2016 ). Furthermore, as sub-lethal concentrations of antibiotics also can select for resistance (Gullberg et al .…”

Panorama da pesquisa sobre tratamento e reúso de efluentes da indústria de antibióticos

“…The acclimatization or prolonged exposure of antibiotic residues to microorganisms may increase their resistance to these compounds, improving their ability to degrade these substances, as compared to Industrial and Sanitary Effluent Treatment Plants containing fluoroquinolone-based antibiotics [45][46][47] . However, this procedure can be a risk, as these microorganisms present in this sludge can carry this resistance to the environment.…”