A metagenomics profiling of rhizospheric microbes in constructed wetlands for Azo dye degradation: Managing abiotic stress for sustainable practices

This study investigates the microbial communities in constructed wetlands (CWs) for azo dye degradation, focusing on managing abiotic stress for sustainable phytoremediation. Metagenomic profiling revealed diverse microbial taxa, particularly Proteobacteria and Bacteroidetes , with notable variations in relative abundance across treatments involving Typha latifolia and Phragmites karka . The presence of these plants influenced microbial composition, promoting the growth of bacteria like Geobacter and Clostridium, indicating that plant-based CWs foster a favorable environment for a broader range of microbes essential for dye degradation. While the control samples showed the highest species richness, the plant-based treatments demonstrated moderate but more specialized microbial diversity, reflecting the selective influence of plant roots on microbial community structure. Beta diversity analysis revealed distinct microbial compositions, especially in Typha-Phragmites combinations, underscoring the role of plant-microbe interactions in CWs. Functional analysis through PICRUSt highlighted pathways crucial for pollutant degradation and greenhouse gas mitigation, including oxidative phosphorylation, nitrogen cycling, and carbon fixation. Post-treatment soil testing indicated enhanced soil health, with optimal pH levels, organic carbon, phosphorus, potassium, and nitrogen forms conducive to plant growth and microbial activity. These improvements were associated with microbial degradation of the dye and subsequent enrichment of beneficial rhizosphere microorganisms. Consequently, seed germination indices reflected improved growth in treatments with Typha and Phragmites , with Typha showing the highest shoot length (63 cm) and Phragmites the longest root length (8 cm). These findings emphasize the potential of plant-based CWs to optimize microbial functions for efficient azo dye degradation, supporting sustainable phytoremediation practices and contributing to improved soil and plant health.