A newly published study reports that actinobacteria isolated from a historic Italian mining site can dramatically improve the capacity of Lemna minor—commonly known as duckweed—to survive and perform phytoremediation under heavy metal stress. The research identifies a promising microbial–plant partnership that could support future eco-friendly strategies for cleaning contaminated water bodies.
Researchers collected samples from different sections of an Italian mine and examined their microbial communities using DNA metabarcoding. They found that the samples were dominated by Proteobacteria and Bacteroidota, with numerous uncultured and unknown taxa. From these environments, scientists successfully isolated ten actinobacterial strains exhibiting diverse tolerance levels to heavy metals such as cadmium, copper, nickel, and zinc.
After evaluating their plant growth-promoting traits—including phosphate solubilization, siderophore production, ammonia and HCN production—the two most promising isolates, MTW 1 and MTW 5, were selected. Both strains were identified through 16S rRNA sequencing as Streptomyces atratus (99.57% identity).
The two strains were combined into a microbial consortium and tested on Lemna minor in controlled in-planta experiments. Results showed that the consortium enhanced plant growth, increased chlorophyll content, and improved tolerance under heavy metal stress. Although biomass and root length increases were not always statistically significant, the survival rate and physiological health of inoculated plants remained substantially higher than untreated controls under metal stress conditions.
These findings demonstrate that metal-tolerant actinobacteria hold strong potential as bioaugmentation agents to enhance phytoremediation in polluted aquatic environments. The study positions Streptomyces-based inoculants as viable, sustainable tools for improving plant-mediated environmental cleanup.
Reference
Djebaili, R., Farda, B., Gialdini, O., Vaccarelli, I., Rezaee Danesh, Y., & Pellegrini, M. (2025). Microbial Consortium of Streptomyces spp. from Mining Environments Enhances Phytoremediation Potential of Lemna minor L. Plants, 14(22), 3467. https://doi.org/10.3390/plants14223467
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