Abundance and diversity of culturable Pseudomonas constitute sensitive indicators for adverse long-term copper impacts in soil

For a field site heavily contaminated with copper more than 80 years ago, copper decreased the abundance of culturable Pseudomonas more than the relative abundance of Pseudomonas 16S rRNA genes. Moreover, the abundance and diversity of culturable Pseudomonas decreased more than those of culturable heterotrophic bacteria. This indicates that the Pseudomonas population is not resilient towards copper stress and that culturable Pseudomonas spp. comprise sensitive bio-indicators of adverse copper impacts in contaminated soils. Further this study shows that copper exposure decreases bacterial diversity at the species or sub-species level, while previous studies for the same soils showed no effect on the diversity of higher taxonomic ranks.