What question did this study set out to answer?

This research aims to reduce arsenic uptake in rice by engineering a specific strain of Bacillus subtilis to enhance iron plaque and biofilm formation.

May 16, 2026

Engineered Bacillus subtilis p43‐ Taglo1 fortifies the iron plaque‐biofilm composite to reduce arsenic uptake and promote rice growth

Key Points

This research aims to reduce arsenic uptake in rice by engineering a specific strain of Bacillus subtilis to enhance iron plaque and biofilm formation.
Engineered Bacillus subtilis p43-Taglo1 was tested in a contaminated paddy for its effects on rice growth and arsenic uptake.
Grain yields and arsenic levels were measured and compared to wild-type strains.
Transcriptomic analysis assessed gene expression changes related to key pathways in both bacteria and rice roots.
Grain yield increased by 10.7-11.6% and grain arsenic levels decreased by 28.2-37.4% compared to wild-type.
Inoculation resulted in a 2.87-fold increase in Fe(II) oxidation and enhanced production of EPS (1.4-fold) and siderophores (1.5-fold).
Upregulation of bacterial genes associated with Fe(II) oxidation and downregulation of rice root arsenite transporters were noted.

Abstract

Arsenic contamination threatens rice (Oryza sativa) production, yet the synergistic use of iron plaque (IP) and root-associated biofilms as a rhizosphere barrier to limit arsenic uptake remains unexplored. To address this, we engineered an arsenic-resistant (AR) plant growth-promoting rhizobacterium (AR-PGPR), Bacillus subtilis p43-Taglo1, expressing the speciation-inert arsenic-binding protein TaGlo1. In a contaminated paddy, this strain increased grain yield by 10.7-11.6% and reduced grain arsenic by 28.2-37.4% compared to the wild-type. The engineered strain robustly colonized roots and enhanced the formation of a functional IP-biofilm composite, which sequestered more arsenic. This was driven by a 2.87-fold increase in Fe(II) oxidation and elevated production of extracellular polymeric substances (EPS) (1.4-fold) and siderophores (1.5-fold). Transcriptomic analysis revealed that inoculation upregulated bacterial genes for Fe(II) oxidation, siderophore, and EPS biosynthesis, while in rice roots, it activated phytohormone pathways and downregulated arsenite transporters (OsLsi1 and OsLsi2). We conclude that AR-PGPR can restore beneficial root-microbe interactions under arsenic stress. The IP-biofilm composite acts as an inducible barrier essential for the dual benefits of arsenic exclusion and growth promotion. Our study shows that AR rhizobacteria fortify the IP-biofilm composite to reduce arsenic uptake and promote rice growth, providing a route toward safer rice production in arsenic-affected regions.

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