Soil bacteria share amino acids, helping nearly half survive nutrient gaps

A recent study by Osnabrück University, in collaboration with researchers from the University of Cambridge, has uncovered a fascinating aspect of soil bacteria. The findings, published in the journal Nature Microbiology, reveal that nearly half of the isolated soil bacteria lack the ability to synthesize certain amino acids independently. These bacteria, known as auxotrophs, rely on nutrient exchanges with other bacteria to survive.

The research team, led by Prof. Dr. Christian Kost, collected soil samples from Jena, Thuringia, and isolated nearly 7,000 bacterial strains from 27 bacterial communities. In the laboratory, they tested which bacteria could produce amino acids on their own and which depended on nutrient uptake from the environment. The results showed that about half of the bacteria in each community were unable to produce amino acids independently.

Further experiments demonstrated that isolated auxotrophic bacteria in mixed cultures received the necessary nutrients from other bacterial strains, leading to their growth dependence on such a supply. Genetic analysis suggested that mobile DNA segments, known to disrupt the independent production of amino acids, might explain the origin of these auxotrophies.

The study supports the "Black Queen hypothesis," which posits that auxotrophic bacteria exist in soil communities to facilitate nutrient-sharing networks, enabling their survival. This research offers new insights into how bacteria coexist in their natural environment and has implications for understanding bacterial communities in biomedicine and agriculture.