Date: 24.06.2019

Indigenous soil microorganisms are essential to prevent dissemination of risky genes in soil from animal manure

The increasing resistance of bacteria to antibiotic drugs is one of the major challenges facing human and veterinary medicine in the 21st century. Both research and practice recognize that antibiotic resistance (ATB-r) is a complex environmental and evolutionary problem, demanding a better understanding of the mechanisms involved in ATB-r spreading in the environment.

How do risky ATB-r bacteria and relevant genes get into the environment? Most often, they reach rivers from sewage treatment plants, where they arrive with human excrements or from animal mass production farms in the form of fertilizer for agricultural soils. A research team led by D. Elhottová (Institute of Soil Biology, BC CAS) has experimentally verified the role of soil microorganisms in transferring ATB-r genes from faeces of ATB-treated cows to healthy and damaged soil. The experiment used an original model of horizontal layering simulating the natural manure deposition in the environment.

The results showed that healthy soils (undisturbed microbiome) amended with cow faeces prevented the entry of risky ATB-r bacteria and genes as compared to soils with a strongly disrupted microbiome. Moreover, the results highlighted the importance of indigenous microorganisms for soil fertility following manure application, as soils with undisturbed microbiome showed higher content of important nutrients such as nitrogen and phosphorous. Therefore, these results indicate that native soil bacteria may hinder the soil enrichment by genes of antibiotic resistance and have a relevant role in improving soil fertility after manure amendments.

The aim of the research is to understand in detail the key relationships and mechanisms governing the spread of resistance to ATB, which will enable to anticipate and eliminate the risks associated with manure fertilization of agricultural soils. This does not mean that we must reduce organic fertilization of soil in practice. Our farmland needs to be replenished with organic matter and manure, which has to get into the soil as a non-contaminated high-quality supplement, is the best for it. At the same time, it is clear that highly-diverse and balanced communities of indigenous soil microorganisms like those present in healthy soils are essential for biological control and soil fertilization.

 

The results were published in Scientific Reports, a journal from the Nature Publishing Group.

 

Full reference

Pérez-Valera, E., Kyselková, M., Ahmed, E., Sladecek, F. X. J., Goberna, M., & Elhottová, D. (2019). Native soil microorganisms hinder the soil enrichment with antibiotic resistance genes following manure applications. Scientific Reports, 9, 6760. doi:10.1038/s41598-019-42734-5

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