Bacterial 16S rRNA diversity of metalliferous soil amended with municipal soil compost and water treatment residues. soil metagenome

Iron-rich water treatment residues (Fe-WTRs) and municipal solid waste compost (MSWC) were added at 1 and 2 % (w./w.) total rates (i.e. 0.5%Fe-WTRs+0.5%MSWC and 1% Fe-WTRs+1%MSWC) to a degraded sub-alkaline soil (pH 8.0) contaminated with critical levels of Sb (~110 mg·kg-1 soil), Pb (~1,200 mg·kg-1 soil), Cd (~23 mg·kg-1 soil), and Zn (~5,400 mg·kg-1 soil). Both treatments significantly reduced the labile fractions of the metal(loid)s in soil while increasing the abundance of culturable heterotrophic bacteria, actinomycetes and fungi. Soil enzyme activities, i.e. dehydrogenase, β-glucosidase and urease, were also significantly stimulated in the treated soils. The amendment addition had a profound impact on the structure of the soil microbial community as highlighted by the Biolog Community Level Physiological Profiles and by high throughput partial 16S rRNA gene sequencing. Plant growth (Helichrysum italicum) in the treated soils was greatly stimulated while metal(loid)s uptake was significantly reduced.Overall the amendments applied were effective at reducing the mobility and bioavailability of both Sb and selected co-occurring metals and improved soil microbial and functional traits. Moreover, H. italicum appeared as a promising plant species for aided phytostabilisation of metal(loid)s contaminated soils.