This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Viewed under a microscope, the air above the Amazon rainforest teems with activity. It is full of pollen, fungal spores, tiny plant particles and bacteria.
Normally, the composition of this bioaerosol community is quite stable. A team that included researchers from the University of Graz, the Max Planck Institute for Chemistry in Mainz and Brazilian partner institutions has now shown that microorganisms are transported across the Atlantic along with desert dust from the Sahara. According to the study, published in the journal Communications Earth & Environment, the bacterial composition of the air changes significantly when dust clouds from Africa reach the rainforest.
The composition of fungal spores in the Amazon's air, however, remains largely the same. In February 2020, a team led by Bettina Weber of the University of Graz collected aerosol samples daily over a three-week period at various altitudes above the Amazon rainforest in Brazil. On five of these days, the researchers recorded the transport of desert dust from North Africa into the region.
The researchers conducted genetic analyses of the collected samples to determine their microbiological composition, particularly the bacteria and fungi they contained. Following the dust influx, the researchers found numerous bacteria on the filter samples that typically occur in dry soils, in addition to "native" bacteria. The researchers attribute the largely unchanged fungal community to the large quantities of spores released by the rainforest, meaning that fungal spores from the Sahara did not significantly affect the analyses.
"Soils in arid regions and deserts are largely colonized by microbial communities, known as biological soil crusts. Genetically, the bacteria match organisms from the Sahara, which proves that they are transported from African biocrusts across the Atlantic by wind all the way to Brazil's rainforest," explains study leader Bettina Weber, who is a professor at the University of Graz and collaborates closely with the Max Planck Institute for Chemistry. In addition, the scientists found that the concentration of endotoxins in the air tripled with the arrival of Saharan dust.
Endotoxins are found in the cell membranes of certain bacteria and are released when the bacteria die. In humans, these chemically stable compounds can lead to inflammation. "I was surprised by the large amount of endotoxins in the air," comments Jens Weber, who conducted the research as part of his doctoral studies.
Extract — continue reading at the source.
