Heavy Metals Influence on the Bacterial Community of Soils: A Review

The increasing rate of natural resource use leads to an increase in the anthropogenic load on the soil. As the result of industrial, metallurgical and mining activities, excessive amounts of heavy metals (HMs) enter the soil. In addition, they can be introduced with waste and drainage water from various enterprises. Accumulating in the soil, HMs can negatively affect the soil bacterial community, which is one of the main factors of its “health”. Molecular genetic methods based on shotgun sequencing or metabarcoding of standard DNA sequences (for example, the 16S rRNA gene for bacteria) are the modern ways to assess the bacterial diversity of soils. This review presents the results of modern studies on the effect of HMs on the soil bacterial communities, using metagenomic methods. Based on the analysis of publications over the past two decades, a generally negative effect of pollutants on the taxonomic composition and diversity of bacterial communities has been shown. The influence of factors modulating the toxicity of metals and metalloids was noted: the amount and composition of salts, soil pH, ecosystem type, rhizosphere presence and other soil properties. In this paper, promising directions of research are outlined.