Soil, particularly soil in an area of vast plant biodiversity, is full of bacteria. The Netflix documentary Kiss the Ground explains this effectively: 'plants are feeding soil microorganisms carbon, and the soil microorganisms are bringing the plants mineral nutrients'. This is the reciprocal relationship between trees and bacteria, and it is an essential means of carbon sequestration in soil.
So when plants are removed from this relationship, as they are being in the Amazon, bacteria are likely to behave differently. As Lucas William Mendes, an author of the new research paper into soil bacteria, has explained:
'Bacteria produce substances with which to attack each other in a competition for resources that's usual in any environment. When an area is deforested, however, several factors intensify this competition, favoring the bacteria that can resist these substances. If they reach humans, these microorganisms can become a major problem'.
'Our results demonstrated that these soils are a reservoir of a huge diversity of [antibiotic-resistant genes]'.
The diversity of antibiotic-resistant genes (ARGs) in Amazon soil samples was worryingly high: 'Overall, we detected more than 145 ARGs involved in 21 functional mechanisms across the different land-use systems. Our results demonstrated that these soils are a reservoir of a huge diversity of ARGs. We observed that the conversion of native forest to agricultural land and cattle pastures increased the abundance of different functional mechanisms and ARGs'.
It has been well-documented that the main cause of Amazon deforestation is the meat industry, the second-largest being soy production for the sake of animal feed. It is also well-known that antibiotics are widely over-utilised in industrial meat production, which has already been a major concern for the scientific community. This new study links that overuse directly to the extra biodiversity of ARGs:
'The use of antibiotics is common in animal husbandry, with diverse types of ARGs being identified in livestock waste'. The study found that animal waste was transferring antibiotic resistant bacteria directly into soil. Crucially, they found that this was a two-way impact:
'Whereas Amazon deforestation aims to increase food production following the increasing global demand, our results highlight the increased diversity of ARGs in the soil reservoir with the potential to enter the food chain through the consumption of meat, vegetables, and other food sources', the authors of the study wrote. So, these drug-resistant bacteria have a high chance of being distributed throughout the world’s food networks.
The UK currently imports soy in large quantities from deforested land in the Amazon rainforest, and uses it to raise livestock that we end up purchasing the meat from in almost every British supermarket. It is likely that this is the greatest aspect of our deforestation footprint, and Greenpeace have been campaigning to draw attention to the illegal imports of deforestation-related products into the country.
This study is further evidence of the vital need to prevent all deforestation in the Amazon rainforest.