Distinct mineral weathering effectiveness and metabolic activity between mineral-weathering bacteria Burkholderia metallica F22 and Burkholderia phytofirmans G34

Bacteria play important roles in mineral weathering, soil formation, and the cycling of elements. However, little is known regarding the interactions between silicate minerals and Burkholderia strains. In this study, mineral-weathering bacteria Burkholderia metallica F22 and B. phytofirmans G34 isolated from the rhizosphere soil of a dominant grass (Deyeuxia arundinacea L. Beauv) grown on mineral-rich and nutrient-poor soil were compared for their potash feldspar weathering and metabolic activities during the mineral weathering process. Although the two strains showed similar mobilization of Si, strain F22 demonstrated significantly higher Al (ranging from 41% to 143%) and Fe (ranging from 47% to 4.8-fold) mobilization from the mineral compared to strain G34. In addition, strain F22 produced higher gluconic acid (ranging from 68% to 24-fold) and exopolysaccharides (ranging from 57% to 2.2-fold) than strain G34. Significantly lower pH (ranging from 2.61 to 3.45) and higher dehydrogenase activity (ranging from 24% to 19-fold) were observed in the presence of strain F22 than in the presence of strain G34 during the mineral weathering process. Redundancy analysis illustrated strong positive correlations between the concentrations of gluconic acid and exopolysaccharides and the dissolved Al and Fe. These results demonstrated that the two mineral-weathering Burkholderia strains behaved differently with respect to mineral weathering and in their metabolic activities. The results also suggested that Burkholderia metallica F22 promoted potash feldspar weathering by increasing mineral weathering-related metabolic activities during the weathering process.