Scientists create first map of soil antibiotic resistance genes

Chinese scientists have compiled the world's first distribution map of soil antibiotic resistance genes by using big data from soil metagenomics. The genes themselves have been recognized in recent decades as "new pollutants" that pose a serious threat to human health.

Researchers from the School of Geographic Sciences of East China Normal University have revealed the geographical pattern and the driving mechanism of soil microbial drug resistance worldwide, which can help guide efforts to control soil ARGs and mitigate their impacts.

Their research was published in the academic journal Science Advances on Nov 16 under the title Global Biogeography and Projection of Soil Antibiotic Resistance Genes.

The massive use and misuse of antibiotics have resulted in the selective enrichment of ARGs in microorganisms in the environment, and the acquisition of ARGs by pathogenic bacteria would lead to problems in antibiotic treatment, posing a serious threat to the health of human beings and animals, according to the research team.

Therefore, antibiotics and ARGs are considered new pollutants. Yet the spatial distribution of soil ARGs in the world, and which factors would affect their geographical structure, remain unclear.

This knowledge gap has seriously hindered comprehensive understanding and effective control of soil ARGs.

"From the perspective of big data mining and environmental geography, this study leads the direction of research into soil ARGs," said Liu Min, leader of the research team.

The research team annotated the ARGs in the global soil environment, discovering that ARG abundance in agricultural soils was significantly higher than in nonagricultural soils, and multi-drug resistance genes were the dominant type of ARGs.

After annotating the gene sequences carrying ARGs, the research team found that ARGs were mostly carried by gut microbes and clinical pathogens.

Further analysis revealed that human activities can increase the abundance of soil ARGs by introducing gut microbes and clinical pathogens into farmland via the use of agricultural sludge and manure.

Geographical factors including the physical and chemical properties of soils, temperature and precipitation can also indirectly increase soil antibiotic resistance.

Through the use of machine learning, the research team completed a global map of soil ARG abundance, discovering that soil ARG hot spots are primarily found in areas with dense populations and well-developed agriculture and animal husbandry in the eastern part of the United States, Western Europe, South Asia and East Asia.

Based on the finding, the research team proposed that soil ARGs in the aforementioned areas be controlled by reducing the use of antibiotics, sewage irrigation and feces.

"The research results are of great practical significance to the United Nations Sustainable Development Goal 3: Good Health and Well-being, providing a foundation for the implementation of WHO's global action plan on antibiotic resistance, and the State Council of China's Action Plan on Controlling New Pollutants," Liu said.