The long-term effect of glutaraldehyde on the bacterial community in anaerobic ammonium oxidation reactor

A 160-day incubation was performed with two anammox reactors (GA and CK) to investigate the effect of glutaraldehyde. The results indicated that anammox bacteria were very sensitive when glutaraldehyde in GA reactor increased to 40 mg/L, the nitrogen removal efficiency sharply decreased to 11%, only one-quarter of CK. Glutaraldehyde changed spatial distribution of exopolysaccharides, caused anammox bacteria (Brocadia CK_gra75) to disassociate from granules (24.70% of the reads in CK but only 14.09% in GA granules). Metagenome analysis indicated glutaraldehyde led to the denitrifier community succession from strains without nir (nitrite reductase) and nor (nitric oxide reductases) genes to those with them, and the rapid growth of denitrifiers with NodT (an outer membrane factor)-related efflux pumps replacing those with another TolC -related ones. Meanwhile, Brocadia CK_gra75 lacks the NodT proteins. This study provides important insight into community adaptation and potential resistance mechanism in an active anammox community after exposure to disinfectant.

Automated summary

A 160-day incubation was conducted to investigate the effect of glutaraldehyde on anammox bacteria. The results showed that the nitrogen removal efficiency significantly decreased to 11% in the GA reactor when the glutaraldehyde concentration reached 40 mg/L, which was only one-quarter of that in the CK reactor. Glutaraldehyde caused the dissociation of anammox bacteria from granules and led to the succession of denitrifier community. Metagenome analysis revealed the replacement of denitrifiers with different efflux pumps and the lack of NodT proteins in a specific strain.