Saline soil reclamation by halophytes increased soil multifunctionality through modulation of soil microbial communities

Abstract Background: Planting halophytes is an efficient way of remediating saline soils, but with undetermined consequences for the soil microbial communities and functioning of the soil ecosystem. Here, we investigated how halophyte-mediated reclamation influences soil microbial diversity and how changes in microbial networks may subsequently alter soil functioning during five years of phytoremediation on saline soils. Results: Phytoremediation increasedthe overall microbial diversity and enriched specific microbialgroups such as Gammaproteobacteria,Chloroflexi, and Gemmatimonadetes, and some known halophilic bacteria like Marinobacter and Halomonas. In contrast, other microbial groups such as Firmicutes, Betaproteobacteria,Basidiomycota and Zygomycota decreased in the phytoremediated soils. Network analysis showed positive associations between the taxa richness of a core network module and soil functional genes associated with nutrient cycling. The genomes clustered with taxa in modules indicated that taxa within core module had higher gene copies of essential functional genes associated with carbon, and nitrogen cycling. These taxa, including Rhodobacteraceae,Hyphomicrobiaceae, Nocardioidaceae and Acidobacteria-6, were also associated with potential nitrifying bacteria, nitrogen fixers, and decomposers. In addition, the reclaimed soil supported higher taxa richness of core module, which yielded greater soil multifunctionality. Conclusions: Our work highlights microbial taxa within network module strongly correlated with soil functioning during phytoremediation. Furthermore, our study also suggests that while there was no change in the overall soil salinity level, phytoremediation increased soil multifunctionality by enhancing the microbial diversity and altering specific groups of the soil microbiome, suggesting a sign of successful reclamation.