Effect of antibiotics on the cellulolytic and nitrification activity of gray forest soil

Abstract

Aim. To investigate the effect of certain antibiotics - tylosin, oxytetracycline and benzylpenicillin - on the potential nitrifying and cellulolytic activity of gray forest soil using laboratory model research methods.Material and Methods. The object of the research was agricultural gray forest medium loamy soil. The study was carried out by conducting laboratory model experiments. The analysed samples were incubated at 27°C and in the absence of illumination for 30 days and then subsequently analysed for cellulolytic activity (by the application method) and nitrification activity (by the potentiometric method). The taxonomic composition of the bacterial community of the studied soil was established based on analysis of amplicon libraries of fragments of ribosomal operons of 16S rRNA genes by the NGS method.Results. The largest number of nitrification organisms in the soil studied were archaea of the family Nitrososphaeraceae which are autotrophic ammonium oxidants. Most resistant to the effects of the antibiotics used was cellulolytic activity which was suppressed only by the addition of tylosin and its admixture with oxytetracycline. The nitrification activity of the soil varied depending on the concentration and preparations applied, the greatest inhibitory effect being exerted by tylosin. Antibiotic mixtures slightly enhanced the nitrification process at 50-100 mg/kg and were suppressed in the range of 150-700 mg/kg. Conclusion. Once in the soil, the antibiotics studied are capable of both stimulating and inhibiting enzymatic processes. Mixtures of antibiotics rather than their individual applications produce the greatest impact. In medium loamy gray forest soil the presence of antibiotics is more dangerous to nitrification activity.