Evidence of Geobacter-associated phage in a uranium-contaminated aquifer

Abstract

Geobacter species may be important agents in the bioremediation of organic and metal contaminants in the subsurface, but as yet unknown factors limit the in situ growth of subsurface Geobacter well below rates predicted by analysis of gene expression or in silico metabolic modeling. Analysis of the genomes of five different Geobacter species recovered from contaminated subsurface sites indicated that each of the isolates had been infected with phage. Geobacterassociated phage sequences were also detected by metagenomic and proteomic analysis of samples from a uranium-contaminated aquifer undergoing in situ bioremediation, and phage particles were detected by microscopic analysis in groundwater collected from sediment enrichment cultures. Transcript abundance for genes from the Geobacter-associated phage structural proteins, tail tube Gp19 and baseplate J, increased in the groundwater in response to the growth of Geobacter species when acetate was added, and then declined as the number of Geobacter decreased. Western blot analysis of a Geobacter-associated tail tube protein Gp19 in the groundwater demonstrated that its abundance tracked with the abundance of Geobacter species. These results suggest that the enhanced growth of Geobacter species in the subsurface associated with in situ uranium bioremediation increased the abundance and activity of Geobacter-associated phage and show that future studies should focus on how these phages might be influencing the ecology of this site.

Discordant phylogenies suggest repeated host shifts in the Fusarium–Euwallacea ambrosia beetle mutualism

“…#2 on avocado from Miami-Dade County, Florida and Euwallacea sp. #4 from Chinese tea in Sri Lanka cultivate two different fusaria, but this is still a relatively narrow range of symbionts compared to other ambrosia beetles, such as Xyleborus spp., where a single beetle can carry multiple symbiont genera (Carrillo et al, 2014;Kostovcik et al, 2014). Although preliminary data suggest that Euwallacea sp.…”

“…AF-9 NRRL 22643 (Norris, 1980). Other fusaria have been reported from various other ambrosia beetles (Kolarik and Hulcr, 2008;Kostovcik et al, 2014), but their phylogenetic identity and ecological function remain unknown. In contrast to the Fusarium-Euwallacea mutualism, where the Fusarium symbiont is transmitted in mycangia and cultivated by females in galleries as a source of nutrition, A. glabripennis vertically transmits FSSC 6 in their gut (Geib et al, 2012), whereas various other fusaria associated with other clades of ambrosia beetles are mostly vectored phoretically (Bateman and Hulcr, unpubl.…”

“…Indeed, the relationship between many ambrosia beetles and their fungi is much more promiscuous than previously thought. Although some beetle groups have their preferred fungal symbionts (Harrington et al, 2014), sympatric beetles may also share a common pool of local ambrosia fungi (Carrillo et al, 2014;Kostovcik et al, 2014). Host-shift speciation appears to be the norm not just among beetles, but also in the broad spectrum of mutualistic associations between other organisms and fungi (reviewed in de Vienne et al, 2013), including the fungus-farming termites (Nobre et al, 2011) and Microbotryum anther smuts on caryophyllaceous hosts (Refrégier et al, 2008).…”

How Deep Can Surface Signals Be Traced in the Critical Zone? Merging Biodiversity with Biogeochemistry Research in a Central German Muschelkalk Landscape

“…In ongoing work, assessment of the in situ viral metagenome will be combined with experiments testing the migration behavior of viral particles in column experiments. In addition to their potential roles as vectors of information flow, the importance of phages for the control of bacterial population densities in aquifer systems has only rarely been addressed (Eydal et al, 2009;Holmes et al, 2015).…”

Protozoan grazing reduces the current output of microbial fuel cells

“…Another factor that may be limiting accumulation of Geobacter biomass during subsurface bioremediation is phage (Holmes et al, 2015). It would not be surprising if phage also play a role in limiting biofilm densities on electrodes harvesting current in sediments.…”