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Cerrado

Effect of rain on soil microbes

The campo sujo vegetation seen on the Pireneus Mountains in the state of Goiás is one of the kinds found in the Cerrado

ANGELA DE PAULA/WIKIMEDIA COMMONSThe campo sujo vegetation seen on the Pireneus Mountains in the state of Goiás is one of the kinds found in the CerradoANGELA DE PAULA/WIKIMEDIA COMMONS

In winter in the Brazilian Highlands, when the soil is almost completely deprived of water, torrential rains suddenly pour down from the sky as if from a huge overturned bucket. The consequences of such an event on the Cerrado vegetation are well known, unlike its effects on microorganisms living in the soil. But that mystery is now being elucidated by the research group led by microbiologist Ricardo Henrique Krüger, at the University of Brasília (PLOS One, February 5, 2016). DNA sequencing of microbial samples collected from the soil in four types of Cerrado vegetation in September, after a period of more than three rainless months, and then in February, when large volumes of water had already soaked the ground, indicated a wide variability in microorganisms present and roles they play, varying with season and the characteristics of the local vegetation. Heat-resistant bacteria predominate in campo sujo vegetation (grasslands with some shrubs and small trees) and in typical Cerrado, when compared to “shadier” formations. Fungi specializing in the decomposition of organic matter were found to be abundant during the dry season in gallery forests, where leaf litter is more abundant. In these microorganisms, the study found a high number of genes related to cell walls and dormancy, interpreted as a reaction to the inhospitable environment and to the acquisition of iron, which is common in Cerrado soils. The interactions between plants and these microscopic beings suggest that microorganisms play a role in the Cerrado’s ability to react to climate change.

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