Phosphate availability modulates the weathering effectiveness and molecular response of Caballeronia mineralivorans...

Minerals and rocks are important reservoirs of nutrients for the soil biota because of their nutritive contents of P, K or Mg. In nutrient-poor environments such as forest soils, microorganisms capable of mobilizing these nutrients gain an ecological advantage. Acidification-based mineral weathering is one of the mechanisms used by these bacteria, but the molecular players involved and their regulation remain poorly characterized.

To fill these gaps, we considered the effective mineral weathering bacterial strain Caballeronia mineralivorans PML1(12). On the basis of the hypothesis that nutrient availability conditions the effectiveness of bacterial mineral weathering, we considered the impact of different nutrients (i.e., Mg, K and P) typically contained in minerals to determine the regulation occurring during the interaction and weathering of biotite using a dual transcriptomic and proteomic approach combined with geochemical analyses.

By varying the concentration of each nutrient in solution, only P, depending on its concentration, conditioned the effectiveness at weathering of strain PML1(12) through acidification. The combination of omic approaches combined with (geo)chemical analyses revealed how the effectiveness at weathering apatite of strain PML1(12) is influenced by the P concentration and highlighted which mineral weathering (MWe) mechanisms are employed and how they are regulated.

Our analyses provided new information on mineral weathering bacteria and highlighted the differential regulation of the glucose-methanol-choline oxidoreductase depending on the presence of minerals and the phosphorus concentration.