Insights into the community structure and environmental functions of water hyacinth rhizobiome in urban river ecosystem

Water hyacinth (WH) is a widespread floating invasive aquatic plant with a prolific reproductive and dispersion rate. With the aid of its root-associated microbes, WH significantly modulates the ecosystem's functioning. Despite their irrevocable importance, the WH microbiome remains unexplored in detail. Here, we present a shotgun sequencing analysis of WH rhizobiome predominant in urban rivers and their surrounding water to unveil the diversity drivers and functional relationship. The core microbiome of the WH mainly consisted of the methane-metabolizing archaebacteria and sulfate-reducing bacteria, which are probably driving the methane and sulfur metabolic flux along the vegetative zone in the water. The beta diversity analysis revealed temporal variations (River WH_2020 vs. WH_2022) (R of 0.8 to 1 and R² of 0.17 to 0.41), which probably could be attributed to the transient taxa as there was a higher sharing of core bacteria (48%). Also, the WH microbiome significantly differed (R = 0.46 to 1.0 and R² of 0.18 to 0.52) from its surrounding water. Further, the functional analysis predicted 140 pollutant-degrading enzymes (PDEs) well-implicated in various xenobiotic pollutant degradation, including hydrocarbons, plastics, and aromatic dyes. These PDEs were mapped to bacterial genera such as Hydrogenophaga, Ideonella, Rubrivivax, Dechloromonas, and Thauera, which are well-reported for facilitating the metabolism of xenobiotic compounds. The higher prevalence of metal and biocide resistance genes further highlighted the persistence of resistant microbes assisting WH in bioremediation applications.