Assessment of Susceptibility of Sulfonamide Drugs to Biodegradation in Environmental Samples

Sulfonamide drugs enter the environment in different ways, eg through wastewater, creating the potential risk of the generation of drug resistant strains of microorganisms. This risk increases when drugs are resistant to degradation and remain in the environment for a long time. Therefore, it is particularly important to know biodegradability of sulfa drugs since the literature data on this subject are often contradictory. In our study the estimation of susceptibility of four sulfonamides was carried out under aerobic and anaerobic conditions. The mixture of these compounds was added directly to environmental samples or natural wastewater samples (from different sources) or to synthetic wastewater containing inoculum from natural sources. The following effects were studied: aerobic/anaerobic conditions, the availability of light, initial concentrations, pH of the solution, sampling time of inoculum, earlier 40-days adaptation of inoculum to sulfanilamide. The effective biodegradation of sulfonamides was observed in 3 samples of sulfanilamide, 25 samples of sulfadiazine, 29 samples of sulfathiazole and 1 sample of sulfamethoxazole among the all investigated 86 samples. It was found that the biodegradation of sulfonamides differ significantly from the results presented in the literature. Moreover, the dynamics of this process depends mainly on the type of sulfonamide, the origin of inoculum and the sampling time.