Антибіотики в агроекосистемах: мікробіом і резистом ґрунту

Abstract

Contamination of agroecosystems with antibiotics is a serious problem nowadays. Impact of antibiotic contaminants into the environment is unknown, and concerns have been raised about the health of humans, animals, and agroecosystems. Despite increased research focused on antibiotics and antibiotic resistance last years, standard methods and practices for analyzing environmental samples are limited and future research needs are becoming evident. Antibiotics play a key role in the management of infectious diseases for humans, animals, livestock, and aquacultures all over the world. The release of increasing amount of antibiotics into waters and soils creates a potential threat to all microorganisms in these environments. Environmental contamination with antibiotics is one of factors that define the health consequences of antibiotic resistance in bacteria. Fluoroquinolones are one of the most used classes of antibiotics. Enrofloxacin belongs to the class of fluoroquinolone antibiotics that have been intensively used for treatment of bacterial infections in veterinary medicine. In the environment enrofloxacin can undergo degradations by different processes including photolysis, biodegradation and oxidation by mineral oxides but it is not sensitive to hydrolysis. Despite these degradation mechanisms, environmental half life time of enrofloxacin is very long. In this study, the effect of enrofloxacin on the activity and structure of soil microbiome was evaluated. In model ecosystems with different concentrations of enrofloxacin we planted Lactuca sativa var. crispa, Anethum graveolens, Thymus serpillum, Mentha piperita, Calendula officinalis. The most active enrofloxacin from the soil was absorbed by Lactuca sativa var. crispa, and Calendula officinalis. The soil with a high concentration of antibiotic was characterized by a low content of nitrogen-fixing microorganisms and a high number of oligotrophic and spore-forming microbiota. Contamination with antibiotics is also an important factor in formation of soil resistome — the community of soil microorganisms with high level of antibiotic resistance. Thirty seven antibiotic resistant bacterial isolates were cultured from soil. All isolates were multi-drug resistant, of which greater than 64% were resistant to 12 antibiotics, comprising almost all classes of antibiotic. In experiment we isolated 5 bacteria resistant to all tested antibiotics: anaerobic bacteria: Clostridium difficile, Clostridium perfringens and aerobic bacteria: Enterococcus faecalis, Yersinia enterocolitica, Enterobacter cloacae. All of them are antibiotic resistant and are the causative agents of food borne infections. The antibiotic contamination of the soil, cause negative changes in microbial community, and is one of important factors in the formation of soil resistome.