Metagenomic and cytotoxicity insights into the migration behavior and pathogenic potential of multi-medium microorganisms in a wastewater treatment plant.

As important interphases between the human society and natural water environments, wastewater treatment plants (WWTPs) accumulate a variety of human activity-related microorganisms. The characteristics of potential pathogenic microorganisms associated with WWTPs have gradually become a research hotspot. In this study, the distribution characteristics and migration patterns of potential pathogenic genera in different processes, media and seasons were investigated via the metagenomic analysis of samples regularly collected at a typical WWTP in North China. The results obtained 112 pathogenic bacteria and 33 pathogenic fungi in the wastewater, sludge, and bioaerosol samples. Resistance mechanisms were dominated by antibiotic efflux with proportion of 62.63-63.53%. Functional genes encoding offensive virulence factors (VFs) including adherence, secretion system, toxin, invasion, and actin-based motility were the most common category in all the WWTP samples. Network analysis revealed the presence of core antibiotic resistance genes (including mtrA, bcrA, oleC, MexB, PmrE) and core VFs (including Type IV pili (VF0082), HIS-I (VF0334), LOS (CFV494), and Alginate (VF0091)) on multiple microbes, which increased the survival rate of microorganisms even under adverse conditions and enhanced the invasion potential to cause diseases. Additionally, cell exposure experiments confirmed the ability of Pseudomonas aeruginosa to induce inflammatory responses in Beas-2B cells. Based on these findings, which offer the insight of a comprehensive understanding of the potential pathogenicity of microorganisms in WWTPs, it is recommended to improve regulation of effluents from WWTPs a nd the implementation of measures to reduce the risk posed by airborne pathogenic microorganisms.