Lead (Pb) contamination alters richness and diversity of the fungal, but not the bacterial community in pine forest soil

Abstract

The aim of the study was to gain a more detailed view of the changes in microbial community structure in boreal forest soil due to lead contamination. The Hälvälä shooting range in southern Finland is heavily polluted by lead. The humus soil microbial community was examined using DNA based methods. To examine the bacterial community a 400 bp section of the 16S rRNA gene was amplified, cloned, and sequenced. For fungi, the internal transcribed spacer (ITS) area was examined. The 917 bacterial sequences grouped into 398 operational taxonomic units (OTUs) at ≤ 97% similarity, while 649 fungal sequences grouped into 155 OTUs at ≤ 99% similarity. No effect of lead was found on bacterial richness or diversity, while fungal richness and diversity were significantly altered. Some OTUs assigned to Basidiomycota were much rarer in the lead contaminated areas while the genus Thelephora was enriched in the lead contaminated soil. This difference between bacterial and fungal responses to lead suggests a difference in the strategy to avoid the contaminant. The analyses performed here do not, however, allow for conclusions regarding mechanisms.