Fast-growing bacteria crowd plant roots while slow growers hold the surrounding soil
Dang C, Piñeiro Nevado J, Schartiger R, Tripathi BM, Walkup JG
Soil Health
The compost or mulch you add to a garden bed mostly feeds the fast-growing bacteria clustered around roots, and this study shows that crowd can outcompete slower soil microbes for the extra food.
Scientists tracked how quickly different soil bacteria grow and found that fast growers pile up around plant roots, where sugary root leftovers feed them. Away from roots, slow-growing bacteria that get by on little food take over. Add extra carbon, and the fast growers speed up everywhere, but the slower ones only benefit in soil without roots, likely because the roots' bacterial crowd crowds them out.
Key Findings
Based on growth rates measured with 18O isotope labeling, 35% of bacterial taxa were classed as oligotrophs (slowest), 50% as mesotrophs, and 15% as copiotrophs (fastest).
Copiotrophs were more abundant and active in the rhizosphere, while bulk soil was dominated by slow-growing oligotrophs.
Carbon addition raised copiotroph growth in both rhizosphere and bulk soil, but oligotrophs and mesotrophs only benefited in bulk soil, and growth rates showed phylogenetic organization at fine taxonomic levels (families, genera) but not at phylum or order level.
chevron_right Technical Summary
Researchers measured how fast individual soil bacteria grow and used those rates to sort them into slow, medium, and fast growers. Fast growers thrive around plant roots and respond to added carbon, while slow growers dominate the soil away from roots.
Abstract Preview
Original paper
Soil microbial growth rate, trophic strategy, and the oligotroph-copiotroph continuum.
The oligotroph-copiotroph continuum is an ecological framework that describes microbial metabolic traits, habitat preferences, and growth strategies. As microbial growth rates determine soil elemen...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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