Selected rhizobacteria strains improved the tolerance of Vicia faba plants to microcystins contaminated irrigation water and reduced human health risk

Abstract

Abstract In Morocco as well as in many countries located in semi-arid areas, irrigation with water from lake-reservoirs is a common agricultural practice and an important tool for farmers to improve crop yields. However, this kind of water can contain toxic bloom-forming cyanobacteria, and its use as a source for irrigation water can enable a transfer of cyanobacterial toxins (microcystins) into crop plant. When microcystins are accumulated in crop plants, they pose serious human health risk. The aim of this study is to explore the potential of selected rhizobacteria strains in inoculation with Vicia faba plants to mitigate microcystins-induced phytotoxicity and health risks. Irrigation with water containing 200 µg L −1 microcystins reduced plant growth, photosynthetic efficiency, and nitrogen assimilation. Inoculation with selected rhizobacteria strains alleviated these effects, enhancing root biomass, stomatal conductance, chlorophyll content, leaf quantum yield, and nitrogen content and slightly increasing GS activity. Among tested strains, Achromobacter marplatensis showed the strongest protection, reducing microcystin accumulation by approximately 36% compared to uninoculated plants. Estimated daily intake values derived from residual microcystins remained below World Health Organization safety thresholds, indicating a lowered potential risk. These findings demonstrate that soil-based inoculation with targeted rhizosphere bacteria can protect plants from microcystin-induced damage, providing a strain-specific, sustainable bioremediation strategy to maintain crop productivity and food safety in regions exposed to microcystin-contaminated irrigation water.