Risks, characteristics, and control strategies of disinfection-residual-bacteria (DRB) from the perspective of microbial community structure

Abstract

The epidemic of COVID-19 has aroused people's particular attention to biosafety. A growing number of disinfection products have been consumed during this period. However, the flaw of disinfection has not received enough attention, especially in water treatment processes. While cutting down the quantity of microorganisms, disinfection processes exert a considerable selection effect on bacteria and thus reshape the microbial community structure to a great extent, causing the problem of disinfection-residual-bacteria (DRB). These systematic and profound changes could lead to the shift in regrowth potential, bio fouling potential, as well as antibiotic resistance level and might cause a series of potential risks. In this review, we collected and summarized the data from the literature in recent 10 years about the microbial community structure shifting of natural water or wastewater in full-scale treatment plants caused by disinfection. Based on these data, typical DRB with the most reporting frequency after disinfection by chlorine-containing disinfectants, ozone disinfection, and ultraviolet disinfection were identified and summarized, which were the bacteria with a relative abundance of over 5% in the residual bacteria community and the bacteria with an increasing rate of relative abundance over 100% after disinfection. Furthermore, the phylogenic relationship and potential risks of these typical DRB were also analyzed. Twelve out of fifteen typical DRB genera contain pathogenic strains, and many were reported of great secretion ability. Pseudomonas and Acinetobacter possess multiple disinfection resistance and could be considered as model bacteria in future studies of disinfection. We also discussed the growth, secretion, and antibiotic resistance characteristics of DRB, as well as possible control strategies. The DRB phenomenon is not limited to water treatment but also exists in the air and solid disinfection processes, which need more attention and more profound research, especially in the period of COVID-19.

Keywords: Disinfection; Disinfection-residual-bacteria (DRB); Microbial community; Microbial risk; Resistance.

Graphical abstract

Fig. 1

Health, process, and ecological risks of DRB.

Fig. 2

Characteristics changes of microbiome imposed by disinfection.

Fig. 3

Frequency of occurrence of dominant DRB phyla (relative abundance over 5%) (a) and the relative abundance changes of the DRB phyla with top 10 most occurrence frequency after disinfection using chlorine-containing disinfectants (CCD) (b), UV disinfection (c), and Ozone disinfection (d).

Fig. 4

Typical DRB genera and their relative abundance changes during disinfection. Numbers on the right of the boxes indicate the frequency of occurrence of the significant increase in relative abundance (>100%). (CCD: Chlorine-containing disinfectant).

Fig. 5

Phylogenetic tree of typical DRB genera was figured via type strains of each genus. Yellow/violet background indicates that most species in that genus are Gram-negative or Gram-positive, respectively. The red boxes indicate which genera contain pathogens or opportunistic pathogens. Green, violet and blue square after the name of strains represented for the resistance against chlorine-containing disinfectants, UV, and ozone, respectively.

Fig. 6

Venn diagram of typical DRB genera under three most commonly-used disinfection methods (CCD: Chlorine-containing disinfectant).

Fig. 7

Statistics of Alpha diversity indexes shift during disinfection. Data were taken from the field investigation of 54 different water treatment plants in 31 research articles.