Effect of Nonylphenols on the Abundance and Taxonomic Structure of the Soil Microbial Community

A multiple analysis of the impact of the endocrine disruptor nonylphenol on the number of microorganisms, taxonomic structure of the microbial community, and phytotoxicity of a loamy soddy-podzolic soil (Eutric Albic Retisol (Abruptic, Loamic, Aric, Ochric)) was performed in model experiments for the first time. The upper horizons of a loamy soddy-podzolic soil from Leningrad oblast were analyzed. The number and group composition of the soil microbiota were determined by the inoculation of soil suspensions on standard nutrient media. The taxonomic composition of the microbial community was studied using the pyrosequencing method (Illumina MiSeq). The content of nonylphenol in soil samples was determined by high-performance liquid chromatography. The phytotoxicity of the soil samples was evaluated in relation to the test culture of soft wheat (Triticum aestivum). It was found that nonylphenol induces dose- and time-dependent changes in the number of the main physiological groups of soil microorganisms. In the presence of nonylphenol, a significant increase in the number of heterotrophic and oligotrophic microorganisms, as well as of bacteria tolerant to nonylphenol was observed. Actinomycetes and spore-forming bacteria proved to be most sensitive to this chemical. Under the impact of nonylphenol, the species diversity of the soil microbial cenosis decreased. Proteobacteria became the dominant phylum (78%) in the taxonomic structure of the microbial community. In the soil polluted by nonylphenol, the intensity of microbiological mineralization of nitrogen-containing organic substances decreased, and nitrogen immobilization processes were inhibited. The phytotoxicity of the soil samples with a high dose of nonylphenol (300 mg/kg soil) manifested itself during a month-long incubation. The obtained results can be used in developing a scientifically grounded methodology for bioremediation of soils contaminated with endocrine disruptors. Changes in the phylogenetic structure of soil microbial cenoses can serve as a sensitive bioindicator of the ecological soil state.