The earth is swarming with life: first atlas of good soil bacteria
The microorganisms living in the earth and populating our lands (worms, insects, bacteria, and fungi) ensure the proper functioning of the soil. Scientists from the University of Colorado have examined soil bacteria in order to understand their role in the ecosystem. The objective was to identify the “most sought after” good bacteria; those which are thought to be most beneficial for our soils and our crops, and consequently for our health and that of our planet.
Our subsoil is teeming with bacteria which are involved in various crucial ecological processes such as carbon and nutrient cycles, plant production and greenhouse gas emission. Although they have been the subject of many studies for several decades, these microorganisms are still poorly understood as there are just too many of them. It is consequently difficult to fully exploit their functional capacities to improve soil quality and crop production.
Samples taken on 6 continents
A team of American researchers therefore wished to create a map of the bacterial communities present in our soils. To this end, they took samples in 237 different locations across 18 countries and 6 continents, thus covering a wide range of climates and vegetation, ranging from deserts to grasslands and wetlands.
Small dominant group
Through sequencing of the DNA obtained from each soil sample, the researchers then identified the dominant lineages of bacterial species based on their abundance and their presence in several sampling areas simultaneously. Finally, it appears that most species are rare, with the exception of a small subgroup (barely 2%, or 511 species) present in 41% of soils throughout the world. More than half of these 511 species have preferences with regard to habitat, due to local pH or climate (aridity, maximum temperature, humidity level). Their abundance in a particular soil reflects the health and fertility of the ground, hence its usefulness for crop production.
Anticipating ecological changes
The researchers consider that this study has immense value. Through a better understanding of the roles of these microbes in our ecosystem, this mapping of bacterial communities in soils—the first of its kind—could help forecast the ecological consequences of environmental changes on a global scale.
Delgado-Baquerizo et al., Science 359, 320–325 (2018)