Spatial Heterogeneity of Iron-Reducing and Se-Reducing Bacteria between Rice Rhizosphere and Bulk Soil Enhances Se...

Area of Science:

• Soil Science
• Environmental Microbiology
• Biogeochemistry

Background:

• Selenium (Se) transformation in soil dictates its bioavailability and plant uptake.
• Microbial roles in Se transformation within rice rhizospheres are not well understood.

Purpose of the Study:

• Investigate spatial distribution of Se in rice rhizospheres.
• Elucidate the microbial mechanisms governing Se transformation and bioavailability.

Main Methods:

• Spatial analysis of Se distribution in rice rhizospheres.
• Identification of microbial taxa and functional genes involved in Se transformation (iron reduction, Se reduction).

Main Results:

• Se bioavailability is influenced by iron-bound Se release (via iron-reducing bacteria) and Se reduction.
• Sulfate-reducing bacteria carrying the *dsr* gene are key mediators of Se reduction.
• Heterogeneous gene distribution leads to varied Se release and reduction between rhizosphere and bulk soil.
• Rhizosphere Se bioavailability is enhanced by increased iron-bound Se release and reduced Se(IV) reduction.

Conclusions:

• Microbial processes, particularly iron and sulfate reduction, significantly control Se transformation in rice rhizospheres.
• Understanding these microbial mechanisms provides insights for enhancing Se bioavailability in agricultural systems.