|Chee sanford, Joanne|
Submitted to: Water Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/15/2011
Publication Date: 11/15/2011
Citation: Davidson, A.N., Ho, C., Chee Sanford, J.C., Lai, H.Y., Klenzendorf, J.B., Kirisits, M.J. 2011. Characterization of bromate-reducing bacterial isolates and their potential for drinking water treatment. Water Research. 45(18):6051-6062. Interpretive Summary: Bromate is a disinfection by-product in water treatment systems and a concern to human health as a carcinogen. Biological bromate reduction by bacteria is a natural process mediated by known species in many natural environments. Little information about the diversity of species able to reduce bromate is available, however the process has been linked to denitrifying bacteria commonly found in soil and water systems. This study examined several sources of bromate-reducing bacteria, including surface water, groundwater, and natural water sources where pure cultures were obtained that were further tested for their ability to reduce bromate and nitrate. The influence of nitrate on bromate reduction was examined as a competing metabolic processes that would affect the efficiency of bromate rreduction. The significance of the study revealed a surprisingly wider variety of bacterial species that can reduce bromate, even in the presence of nitrate, and the specific activity differs among species as well as between very closely related strains. Knowledge of species characteristics in bromate reduction will enhance development of treatment systems that allow more effective removal of contaminants in natural water systems.
Technical Abstract: The objective of the current study was to isolate and characterize several bromatereducing bacteria and to examine their potential for bioaugmentation to a drinking water treatment process. Fifteen bromate-reducing bacteria were isolated from three sources. According to 16S rRNA gene sequencing, the bromate-reducing bacteria are phylogenetically diverse, representing the Actinobacteria, Bacteroidetes, Firmicutes, and a, b, and g-Proteobacteria. The broad diversity of bromate-reducing bacteria suggests the widespread capability for microbial bromate reduction. While the cometabolism of bromate via nitrate reductase and (per)chlorate reductase has been postulated, five of our bromate-reducing isolates were unable to reduce nitrate or perchlorate. This suggests that a bromate-specific reduction pathway might exist in some microorganisms. Bioaugmentation of activated carbon filters with eight of the bromate-reducing isolates did not significantly decrease start-up time or increase bromate removal as compared to control filters. To optimize bromate reduction in a biological drinking water treatment process, the predominant mechanism of bromate reduction (i.e.,cometabolic or respiratory) needs to be assessed so that appropriate measures can be taken to improve bromate removal.