Anthropogenic remediation of heavy metals selects against natural microbial remediation

Abstract

17In an era of unprecedented environmental change, there have been increasing ecological and 18 global public health concerns associated with exposure to anthropogenic pollutants. While there 19 is a pressing need to remediate polluted ecosystems, human intervention strategies might 20 unwittingly oppose selection for natural detoxification, which is primarily carried out by 21 microbes. We test this possibility in the context of a ubiquitous chemical remediation strategy 22 aimed at targeting toxic metal pollution: the addition of lime-containing materials. Here we show 23 that raising pH by liming decreased the availability of toxic metals in acidic mine-degraded soils, 24 but as a consequence selected against microbial taxa that naturally remediate soil through the 25 production of metal-scavenging siderophores. Understanding the ecological and evolutionary 26 consequences of human intervention on key traits is crucial for the engineering of evolutionary 27 resilient microbial communities, having important implications for human health and 28 biotechnology. 29 30 context of raising pH using lime-containing materials, a common intervention practice aimed at 41 reducing heavy metal toxicity (Wuana and Okieimen 2011). 42Heavy metals (metals and metalloids with a density above 5 g -1 cm 3 ) are ubiquitous 43 components of the Earth's crust (Nriagu and Pacyna 1988). As a result of soaring demands for 44 minerals (Douce 2016), large parts of the world are currently mined for valuable mineral 45 deposits, leaving a legacy of untreated mining waste (Dudka and Adriano 1997). In addition, 46 agricultural practices such as application of sewage sludge and phosphate fertilisers have led to 47

Anthropogenic remediation of heavy metals selects against natural microbial remediation

“…We used R v. 3.1.3 for all analyses (R Development Core Team; http://www.r-project.org). Raw phenotypic data are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.843814d [49].…”

Copper selects for siderophore-mediated virulence in Pseudomonas aeruginosa

“…As the copper concentrations used in this study were chosen for their environmental relevance, we suggest our findings could be relevant to natural communities in polluted environments. We note that remediation techniques, principally lime addition, are used in some metal-polluted areas to reduce their toxic effect (49), and this can lower community siderophore production (50). Extending experiments such as those described here to the level of natural communities could shed light on the consequences of metal pollution and metal remediation on bacterial siderophore production and virulence.…”