Bacterial consortium amendment effectively reduces Pb/Cd bioavailability in soil and their accumulation in wheat

Area of Science:

• Environmental Microbiology
• Agricultural Science
• Soil Science

Background:

• Heavy metal (HM) contamination threatens farmland sustainability and food safety.
• Microbial remediation offers a sustainable approach, but consortium effects on crops under HM stress require clarification.
• Understanding bacterial consortium mechanisms is crucial for optimizing their application.

Purpose of the Study:

• To investigate the impact of a specific bacterial consortium on wheat growth and heavy metal (Pb/Cd) accumulation in contaminated soil.
• To compare the efficacy of the bacterial consortium against single strains in mitigating HM stress and improving soil health.
• To elucidate the mechanisms by which the bacterial consortium enhances plant growth and reduces HM transfer.

Main Methods:

• Pot experiments were conducted using wheat grown in HM-contaminated soil inoculated with a bacterial consortium (Bacillus cereus, Bacillus thuringiensis, Herbaspirillum huttiense) and single strains.
• Plant growth parameters, HM content in soil and plant tissues, soil enzyme activities, and nutrient availability were measured.
• Correlation and least square path analyses were employed to determine the relationships between soil properties, microbial activity, and plant responses.

Main Results:

• The bacterial consortium significantly alleviated HM-induced growth inhibition by activating antioxidant enzymes and inhibiting lipid peroxidation.
• Compared to single strains, the consortium enhanced root development, reduced available HMs in soil (4.5-10.3%), and decreased HM transfer to shoots (4.3-8.4%).
• Bacterial consortium application led to a substantial increase in soil enzyme activities and available nutrients, improving soil quality and plant growth more than twice as effectively as single strains.

Conclusions:

• Bacterial consortiums are superior to single strains in promoting crop growth and mitigating heavy metal contamination in agricultural soils.
• This microbial strategy effectively reduces heavy metal uptake by crops, minimizing risks to the human food chain.
• The study provides a viable strategy for safe food crop production on HM-contaminated farmlands through enhanced microbial remediation.