Deforestation in the Amazon increases the diversity of antibiotic-resistant bacteria

In Brazil, a study by researchers affiliated with the University of São Paulo (USP) and colleagues showed that deforestation in the Amazon causes an increase in the diversity of antibiotic-resistant bacteria.

Article examined, published in Soil biology and biochemistry, comparing the microorganisms living in native forest soils with those found in pastures and crops. The researchers found that a much higher number of genes assessed signs of antibiotic resistance in deforested areas of the forests.

Bacteria make products by which they attack each other in competition for resources that are normal in any environment. When an area is deforested, however, a number of factors strengthen this competition, favoring the bacteria that can resist these substances. If they reach humans, these microorganisms can be a major problem. “

Lucas William Mendes, Last Author Study and Researcher, Center for Nuclear Power in Agriculture (CENA-USP), Piracicaba

The study was part of a project linked to the FAPESP Research Program on the Character of Biodiversity, Conservation, Regeneration and Sustainable Use (BIOTA-FAPESP) and led by Tsai Siu Mui, a professor at CENA-USP.

Fighting antibiotics is a global public health crisis, according to the World Health Organization (WHO), which claims that drug-resistant diseases cause an estimated 700,000 deaths each year worldwide.

In the study, the researchers at CENA-USP, collaborating with colleagues at the Luiz de Queiroz Agricultural College (ESALQ-USP) and scientists at the national laboratory for scientific computing in Petrópolis , Rio de Janeiro State, analyzed some 800 million DNA strands extracted from 48 soil samples collected in Pará State and northern Mato Grosso State, both of which are part of a biome and Amazon.

Using bioinformatics tools, the researchers ran the DNA sequences from the samples against a genetic database and found 145 antibiotic-resistant genes that stimulate 21 different molecular mechanisms. Although antibiotic-resistant bacteria are present in forest soils, these microorganisms and their protective mechanisms are much more abundant in grazing soils, deforestation areas and crop soils.

Deforestation microorganisms

“The process of living in the Amazon involves first listing the most valuable trees and then clearing and burning everything else to make room for crops or supply grass for cattle, “said Mendes.” In addition to ash from the burnt vegetation, the soil is restricted to reduce acidity and other agrochemicals are applied. The abundance of nutrients fuels bacterial proliferation and strong competition for resources. “

Previous studies by the CENA-USP group showed that, despite the reduction in the diversity of forest soil microorganisms, the abundance of bacteria benefited from plants with improved nutrient cycling and photosynthesis, and they also had positive effects on the atmosphere, including carbon sequestration and methane consumption, the second most important greenhouse gas after carbon dioxide.

In the most recent study, the researchers were struck by the high number of bacteria that were resistant to two specific classes of antibiotics, tetracyclines and beta-lactamases.

Medications with these active ingredients are widely used to treat cattle diseases and can reach the soil through feces and urine due to the low uptake of antibiotics in cattle. In addition, the use of livestock manure as a fertilizer can increase the spread of drug-resistant bacteria, according to the researchers.

Scientists cannot be sure that antibiotic-resistant microorganisms are able to migrate from Amazon soil to foods made there, such as cereals, sugar and beef. “Some research assumes that the move may occur, but so far, no study has shown it,” Mendes said. “It needs to be looked at carefully because if these drug-resistant bacteria arrive, they can cause serious public health problems.”

There are no immediate solutions to prevent bacteria from multiplying in arable land. Management approaches that take into account other microorganism activities in addition to promoting crop yields, such as nutrition cycling and reduction of methane-producing species, for example, could help alleviate the problem.

This can be done by transferring natural soil to arable land or by using inoculants, products based on microorganisms that perform important functions in the soil and also reduce the need for fertilizers. and agrochemicals. In fact, the market for microbiome-based agricultural products is expected to exceed US $ 10 billion by 2025.

In the Amazon, solutions and opportunities can be very close to grazing or plantation, in the soil of the native forest.