Microbial community composition and functions are resilient to metal pollution along two forest soil gradients

• Published in: FEMS microbiology ecology Vol. 91; no. 1; pp. 1 - 11
• Main Authors: Azarbad, Hamed, Niklińska, Maria, Laskowski, Ryszard, van Straalen, Nico M., van Gestel, Cornelis A. M., Zhou, Jizhong, He, Zhili, Wen, Chongqing, Röling, Wilfred F. M.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.01.2015
• Subjects: Acidobacteria; Bacteria; Bacteria - genetics; Community composition; Community structure; Composition; Contamination; DNA, Bacterial - genetics; Ecology; Environmental aspects; Environmental Pollution - adverse effects; Forest soils; Forests; Gene sequencing; Genes; Genes, rRNA; Heavy metals; Metal concentrations; Metals - toxicity; Microbial activity; Microbial colonies; Microbial Consortia - drug effects; Microbiology; Microbiomes; Microorganisms; Phylogenetics; Phylogeny; Poland; Pollution; Pollution levels; Relative abundance; RNA, Ribosomal, 16S - genetics; rRNA 16S; Sediment pollution; Soil; Soil contamination; Soil Microbiology; Soil pollution; Soils; Poland; metal pollution; soil microbial communities; GeoChip; Illumina sequencing
• ISSN: 1574-6941; 0168-6496; 1574-6941
• DOI: 10.1093/femsec/fiu003

Despite the global importance of forests, it is virtually unknown how their soil microbial communities adapt at the phylogenetic and functional level to long-term metal pollution. Studying 12 sites located along two distinct gradients of metal pollution in Southern Poland revealed that functional potential and diversity (assessed using GeoChip 4.2) were highly similar across the gradients despite drastically diverging metal contamination levels. Metal pollution level did, however, significantly impact bacterial community structure (as shown by MiSeq Illumina sequencing of 16S rRNA genes), but not bacterial taxon richness and community composition. Metal pollution caused changes in the relative abundance of specific bacterial taxa, including Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Planctomycetes and Proteobacteria. Also, a group of metal-resistance genes showed significant correlations with metal concentrations in soil. Our study showed that microbial communities are resilient to metal pollution; despite differences in community structure, no clear impact of metal pollution levels on overall functional diversity was observed. While screens of phylogenetic marker genes, such as 16S rRNA genes, provide only limited insight into resilience mechanisms, analysis of specific functional genes, e.g. involved in metal resistance, appears to be a more promising strategy. Using two distinct gradients of long-term heavy metal pollution, we found that both microbial community composition as well as functional gene-based structure was only minorly affected by the metal pollution, despite strong differences in metal toxicity along the gradients.