Biology subjects

Hesse, E.

Publications and source records attributed to Hesse, E..

4 recordsLinked to original sources

bioRxiv2018

Anthropogenic remediation of heavy metals selects against natural microbial remediation

In an era of unprecedented environmental change, there have been increasing ecological and global public health concerns associated with exposure to anthropogenic pollutants. While there is a pressing need to remediate polluted ecosystems, human intervention strategies might unwittingly oppose selection for natural detoxification, which is primarily carried out by microbes. We test this possibility in the context of a ubiquitous chemical remediation strategy aimed at targeting toxic metal pollution: the addition of lime-containing materials. Here we show that raising pH by liming decreased the availability of toxic metals in acidic mine-degraded soils, but as a consequence selected against microbial taxa that naturally remediate soil through the production of metal-scavenging siderophores. Understanding the ecological and evolutionary consequences of human intervention on key traits is crucial for the engineering of evolutionary resilient microbial communities, having important implications for human health and biotechnology.

ecology↗

bioRxiv2018

Glucosinolates promote initial population establishment of feral oilseed rape

BackgroundCrops are often selected for traits that confer a selective disadvantage in the wild. A key trait that has been greatly altered by domestication is investment in herbivore defence. It remains unclear, however, whether variation in chemical defence affects a crops ability to colonize semi-natural habitats where it typically has to compete with a resident community. Here, we investigate how breeding efforts aimed at reducing glucosinolate levels in seeds - canonical herbivore deterrents - influence initial establishment of Brassica populations spanning a wild-feral-domesticated gradient.\n\nMethodsWe followed the dynamics of twenty-nine Brassica accessions in two experimental fields by recording life table parameters and vegetation cover biannually over a two-year period. Accessions were selected to vary in their glucosinolate content, and included lines of wild turnip (B. rapa), feral B. napus as well as modern canola and historical oilseed rape cultivars. Populations were established by sowing seeds on bare soil after which the natural vegetation was allowed to regenerate, providing a temporal gradient in the degree of interspecific competition.\n\nResultsPopulations flourished in the first year, but many perished during a second year of growth, in particular those of oilseed rape. Declines coincided with an increase in vegetation cover, but were slower in populations harbouring more glucosinolates. These compounds had opposing effects on different life cycle stages: seedling establishment was greater in high-glucosinolate lines, which traded off with reduced post-recruitment survival. Crucially, the effect of glucosinolates on persistence was lost when focussing on oilseed rape only, but the underlying demographic trade-off remained.\n\nDiscussionOur study illustrates that initial establishment of feral oilseed rape is governed by glucosinolate-mediated trade-offs between seedling recruitment and subsequent survival, with low-glucosinolate lines (modern canola) being most successful when post-recruitment conditions are relatively benign. Such demographic trade-offs likely extend to other species, and must be considered when managing escaped crops and invasive plants.

ecology↗

bioRxiv2018

Using the Wax moth larva Galleria mellonella infection model to detect emerging bacterial pathogens

Climate change, changing farming practices, social and demographic changes and rising levels of antibiotic resistance are likely to lead to future increases in opportunistic bacterial infections that are more difficult to treat. Uncovering the prevalence and identity of pathogenic bacteria in the environment is key to assessing transmission risks. We describe the first use of the Wax moth larva Galleria mellonella, a well-established model for the mammalian innate immune system, to selectively enrich and characterize pathogens from coastal environments in the South West of the U.K. Whole-genome sequencing of highly virulent isolates revealed amongst others a Proteus mirabilis strain carrying the Salmonella SGI1 genomic island not reported from the U.K. before and the recently described species Vibrio injenensis hitherto only reported from human patients in Korea. Our novel method has the power to detect novel bacterial pathogens in the environment that potentially pose a serious risk to public health.

microbiology↗

bioRxiv2017

Ecological selection of siderophore-producing microbial taxa in response to heavy metal contamination

Some microbial public goods can provide both individual and community-wide benefits, and are open to exploitation by non-producing species. One such example is the production of metal-detoxifying siderophores. Here, we investigate whether heavy metals select for increased siderophore production in natural microbial communities, or whether exploitation of this detoxifying effect reduces siderophore production. We show that the proportion of siderophore-producing taxa increases along a natural heavy metal gradient. A causal link between metal contamination and siderophore production was subsequently demonstrated in a microcosm experiment in compost, in which we observed changes in community composition towards taxa that produce relatively more siderophores following copper contamination. We confirmed the selective benefit of siderophores by showing that taxa producing large amount of siderophores suffered less growth inhibition in toxic copper. Our results suggest that ecological selection will favour siderophore-mediated decontamination, with important consequences for potential remediation strategies.\n\nAuthorshipEH, SOB, AL, DJH, EvV, AB conceived and designed the experiment. DJH provided new perspectives. EH, SOB, FB, AL collected the data. EH, FB, NT, DJH carried out the data analyses. EH & AB wrote the first draft of the manuscript, and all authors contributed substantially to revisions.\n\nData accessibilityUpon acceptance, data presented in the manuscript will be made available on Dryad.

ecology↗