Distinct Mineral Weathering Behaviors of the Novel Mineral-Weathering Strains Rhizobium yantingense H66 and Rhizobium etli CFN42

Abstract

Bacteria play important roles in mineral weathering, soil formation, and element cycling. However, little is known about the interaction between silicate minerals and rhizobia. In this study, Rhizobium yantingense H66 (a novel mineral-weathering rhizobium) and Rhizobium etli CFN42 were compared with respect to potash feldspar weathering, mineral surface adsorption, and metabolic activity during the mineral weathering process. Strain H66 showed significantly higher Si, Al, and K mobilization from the mineral and higher ratios of cell numbers on the mineral surface to total cell numbers than strain CFN42. Although the two strains produced gluconic acid, strain H66 also produced acetic, malic, and succinic acids during mineral weathering in lowand high-glucose media. Notably, higher Si, Al, and K releases, higher ratios of cell numbers on the mineral surface to total cell numbers, and a higher production of organic acids by strain H66 were observed in the low-glucose medium than in the highglucose medium. Scanning electron microscope analyses of the mineral surfaces and redundancy analysis showed stronger positive correlations between the mineral surface cell adsorption and mineral weathering, indicated by the dissolved Al and K concentrations. The results showed that the two rhizobia behaved differently with respect to mineral weathering. The results suggested that Rhizobium yantingense H66 promoted potash feldspar weathering through increased adsorption of cells to the mineral surface and through differences in glucose metabolism at low and high nutrient concentrations, especially at low nutrient concentrations. IMPORTANCEThis study reported the potash feldspar weathering, the cell adsorption capacity of the mineral surfaces, and the metabolic differences between the novel mineral-weathering Rhizobium yantingense H66 and Rhizobium etli CFN42 under different nutritional conditions. The results showed that Rhizobium yantingense H66 had a greater ability to weather the mineral in low-and high-glucose media, especially in the low-glucose medium. Furthermore, Rhizobium yantingense H66 promoted mineral weathering through the increased adsorption of cells to the mineral surface and through increased organic acid production. Our results allow us to better comprehend the roles of different rhizobia in silicate mineral weathering, element cycling, and soil formation in various soil environments, providing more insight into the geomicrobial contributions of rhizobia to these processes. Silicate weathering in terrestrial ecosystems plays an important role in the formation of soil and soil nutrients, in neutralization of acid rain, and in the long-term drawdown of atmospheric CO 2 (1-5). Many studies indicate that bacteria can significantly affect mineral dissolution by producing acids and metal-complexing ligands, changing redox conditions, or mediating the formation of secondary mineral phases (6-10). Furthermore, bacterial adhesion to minerals plays an important role in governing bacterial activities and mineral we...

Distinct biotite‐weathering activities of Arthrobacter pascens F74 under different contact conditions

“…To determine the cell number in the culture medium, serial 10‐fold dilutions of bacterial suspensions (10 −4 and 10 −5 ; 0.1 ml) were plated onto LB agar plates and the plates were incubated for 7 days at 28°C, and then the cell numbers per milliliter were calculated. Organic acids were determined according to the method of Chen et al . From each flask, a 2‐L sample was centrifuged at 10,000 rpm for 10 min to remove bacterial cells.…”

“…Specifically, organic acids produced by bacteria play key roles in mineral dissolution . Furthermore, bacterial adhesion to minerals plays an important role in promoting bacterial metabolic activity and mineral weathering . Attached microorganisms dissolve minerals by increasing the concentration of protons, inducing the formation of mineral surface ion complexes, catalyzing redox reactions, and exerting physical forces .…”

Impact of poxB, pta, and ackA genes on mineral‐weathering of Enterobacter cloacae S71

“…Of the filtrate, 15 ml was then centrifuged at 8,943 g for 10 min to remove the cells and possible fine‐grained mineral materials from suspension. Five ml of the supernatant was acidified with HNO 3 (final concentration, 2% (v/v)) to avoid the precipitation of dissolved chemical species and was analyzed for dissolved Al and Fe with an inductively coupled‐plasma optical emission spectrometer (Optimal 2100 DV, Perkin Elmer) . The detection limits for Al and Fe were 0.02 and 0.03 µM, respectively.…”

“…The study of bacterial mineral weathering has largely focused on mineral decomposition and the subsequent release of nutrients , though little is known concerning the underlying molecular mechanisms responsible for these processes . For silicate weathering, novel passive and active iron uptake systems involved in basalt weathering by Cupriavidus metallidurans CH34 were identified using DNA microarrays .…”

Location-Related Differences in Weathering Behaviors and Populations of Culturable Rock-Weathering Bacteria Along a Hillside of a Rock Mountain

“…Furthermore, field observations and laboratory experiments have demonstrated that microbes can accelerate or inhibit rock-and mineral-weathering reactions [2][3][4][5] by producing organic and inorganic acids, protons, and metalcomplexing ligands, changing redox conditions, or mediating formation of secondary mineral phases [2,[6][7][8]. There is a large body of knowledge concerning the mineral-weathering roles, community structure, and distribution of culturable bacteria isolated from various environments [9][10][11][12][13].…”