Identification of the inactivating factors and mechanisms exerted on MS2 coliphage in concentrated synthetic urine

Abstract

Volume reduction (condensation) is a key for the practical usage of human urine as a fertilizer because it enables the saving of storage space and the reduction of transportation cost. However, concentrated urine may carry infectious disease risks resulting from human pathogens frequently present in excreta, though the survival of pathogens in concentrated urine is not well understood. In this study, the inactivation of MS2 coliphage, a surrogate for single-stranded RNA human enteric viruses, in concentrated synthetic urine was investigated. The infectious titer reduction of MS2 coliphage in synthetic urine samples was measured by plaque assay, and the reduction of genome copy number was monitored by reverse transcription-quantitative PCR (RTqPCR). Among chemical-physical conditions such as pH and osmotic pressure, uncharged ammonia was shown to be the predominant factor responsible for MS2 inactivation, independently of urine concentration level. The reduction rate of the viral genome number varied among genome regions, but the comprehensive reduction rate of six genome regions was well correlated with that of the infectious titer of MS2 coliphage. This indicates that genome degradation is the main mechanism driving loss of infectivity, and that RT-qPCR targeting the six genome regions can be used as a culture-independent assay for monitoring infectivity loss of the coliphage in urine. MS2 inactivation rate constants were well predicted by a model using ion composition and speciation in synthetic urine samples, which suggests that MS2 infectivity loss can be estimated solely based on the solution composition, temperature and pH, without explicitly accounting for effects of osmotic pressure.

Evaluating the fate of bacterial indicators, viral indicators, and viruses in water resource recovery facilities

“…One potential mechanism that explains the relationship with coliphage reduction in primary processes and primary effluent ammonia is work by Oishi et al. () that demonstrated that ammonia inactivates the male‐specific coliphage MS2 through genomic damage. It is possible that enterococci may be more susceptible to ammonia than E. coli ; however, further work is needed to confirm these observations.…”

“…These observations suggests that WRRFs with higher influent ammonia concentrations may have higher removals of indicators, except for E. coli, in primary processes than WRRFs with lower influent concentrations of ammonia. One potential mechanism that explains the relationship with coliphage reduction in primary processes and primary effluent ammonia is work by Oishi et al (2017) Research Article that demonstrated that ammonia inactivates the male-specific coliphage MS2 through genomic damage. It is possible that enterococci may be more susceptible to ammonia than E. coli; however, further work is needed to confirm these observations.…”

Resource recovery technologies as microbial risk barriers: towards safe use of excreta in agriculture based on hazard analysis and critical control point

“…48 Previous studies have simulated the fate of E. coli and MS2 in a feed solution using concentrated synthetic urine. 30,49 MS2 was inactivated more slowly than E. coli, and the time for a 5 log 10 inactivation was estimated as 4.8 months and 5 h for 10-folds concentrated non-hydrolyzed and hydrolyzed urine, respectively. Ammonia activity of 10-Environmental Science: Water Research & Technology Critical review fold concentrated urine was approximately 1000 mM.…”