Biochar-based microbial agent reduces U and Cd accumulation in vegetables and improves rhizosphere microecology

Area of Science:

• Environmental Science
• Microbiology
• Soil Science

Background:

• Microbial remediation of soil heavy metals is crucial but faces limitations like nutrient deficiency and low efficiency.
• Existing methods struggle with indigenous microbial competition, hindering practical application.
• Uranium (U) and Cadmium (Cd) contamination poses significant risks to soil and crop health.

Purpose of the Study:

• To develop and evaluate a biochar-based microbial agent (BMA) for remediating U and Cd in soil.
• To assess the impact of BMA on soil properties, microbial community structure, and function.
• To determine the efficacy of BMA in reducing heavy metal accumulation in vegetables and promoting their growth.

Main Methods:

• Prepared a biochar-based microbial agent (BMA) by immobilizing a microbial agent (MA) containing Bacillus subtilis, Bacillus cereus, and Citrobacter sp. on biochar.
• Applied BMA to soil contaminated with U and Cd.
• Analyzed changes in soil organic matter, cation exchange capacity, enzyme activities, and heavy metal availability.
• Quantified U and Cd accumulation in vegetables grown in amended soil.
• Investigated the effects of BMA on rhizosphere soil microbial community structure and function using network analysis.

Main Results:

• BMA significantly increased soil organic matter (58.7%), cation exchange capacity (38.2%), and enzyme activities (42.9%-51.1%).
• Soil availability of U and Cd decreased by 67.4% and 54.2%, respectively, leading to reduced vegetable accumulation.
• BMA application promoted vegetable growth and significantly altered soil microbial communities, increasing beneficial bacteria and decreasing pathogenic fungi.
• Network analysis indicated enhanced microbial community complexity and species compatibility in BMA-amended soil.

Conclusions:

• Biochar-based microbial agent (BMA) is a promising strategy for remediating U and Cd in soil.
• BMA improves soil physicochemical properties and enhances microbial community structure and function.
• BMA effectively suppresses heavy metal accumulation in vegetables and promotes their growth, offering a sustainable solution.