A novel isolated Terrabacter-like bacterium can mineralize 2-aminopyrimidine, the principal metabolite of microbial sulfadiazine degradation.

Recently we showed that during the degradation of sulfadiazine (SDZ) by Microbacterium lacus strain SDZm4 the principal metabolite 2-aminopyrimidine (2-AP) accumulated to the same molar amount in the culture as SDZ disappeared (Tappe et al. Appl Environ Microbiol 79:2572-2577, 2013). Although 2-AP is considered a recalcitrant agent, long-term lysimeter experiments with (14)C-pyrimidine labeled SDZ ([(14)C]pyrSDZ) provided indications for substantial degradation of the pyrimidine moiety of the SDZ molecule.

Degradation of sulfadiazine by Microbacterium lacus strain SDZm4, isolated from lysimeters previously manured with slurry from sulfadiazine-medicated pigs.

Sulfadiazine (SDZ)-degrading bacterial cultures were enriched from the topsoil layer of lysimeters that were formerly treated with manure from pigs medicated with (14)C-labeled SDZ. The loss of about 35% of the applied radioactivity after an incubation period of 3 years was attributed to CO2 release due to mineralization processes in the lysimeters. Microcosm experiments with moist soil and soil slurries originating from these lysimeters confirmed the presumed mineralization potential, and an SDZ-degrading bacterium was isolated.

Growth-inhibitory effects of sulfonamides at different pH: dissimilar susceptibility patterns of a soil bacterium and a test bacterium used for antibiotic assays.

The ionic speciation of sulfonamides is pH-driven and this may be crucial for their bioavailability and sorption to soil constituents, as well as for their uptake into bacterial cells. The inhibition behaviour of a bacterial test strain (Pseudomonas aeruginosa; DSM 1117), which was grown in the presence of different concentrations of 8 sulfonamides at pH values from 5 to 8, could be predicted by models that take the speciation of sulfonamides in- and outside of bacterial cells into account. Assuming a pH of 7.