Below is a selection of current or recent research activities in the Melbourne Geomicrobiology Lab.  For relevant peer-reviewed papers, click on the Publications tab, above.

Bioremediating mining-generated contaminants

Thiocyanate and heavy metals are common toxic contaminants from gold mining operations. Some microorganisms can biodegrade thiocyanate and transform toxic metals into less toxic or relatively immobile forms. Our lab studies the microbes that can perform these useful functions, both ex situ and in situ, and aims to understand how to optimise their use in bioremediation strategies. We apply genome-resolved metagenomics, laboratory bioreactor experiments and field pilot-scale studies to develop novel approaches to thiocyanate biodegradation from mine tailings and contaminated groundwater.

Effects of CO2 geosequestration on the terrestrial deep biosphere

Geosequestration of supercritical CO2 is currently seen as a viable strategy for mitigating emissions of this greenhouse gas to the atmosphere by coal-fired power generation plants. However, little to no information exists about how deep subsurface microbial communities may respond to supercritical CO2 exposure. We have studied this process at the Otway Basin CO2CRC site in Western Victoria and in laboratory experiments, to understand the effects of elevated CO2 on microbial physiology, metabolism, and capacity to produce biofilm or mediate mineral dissolution/precipitation reactions.

Geomicrobiology of mercury methylation in polar regions

Atmospheric photochemical reactions during the southern polar spring catalyse the rapid deposition of reactive mercury onto Antarctic sea ice and surface waters, with implications for uptake into Southern Ocean marine food webs. We are investigating how sea-ice and seawater microbial communities react to this sudden increase in reactive mercury. Using mercury stable isotope measurements and metagenomics, we look for correlations between mercury speciation and presence/activity of mercury resistance or methylation genes. Our aim is to reconstruct how microbial systems in extreme cold environments contribute to polar biogeochemical mercury cycling.

Geomicrobiology of iron and sulfur cycling in coastal acid-sulfate soil systems

Coastal acid-sulfate soils (CASS) and acid-mine drainage (AMD) impacted wetlands are major environmental contamination problems in Australia and worldwide. Key microbial "players" involved in controlling acidification and the potential dispersion of toxic metals in both types of settings are the iron-reducing, sulfide-oxidizing and sulfate-reducing bacteria. We are using targeted transcriptomics to study the activity and phylogeny of key metabolic and functional genes of microbial populations in CASS and AMD systems as they compete for electrons under oscillating (diurnally or tidally-driven) redox conditions.

The Impacts of microbial activity on Aboriginal rock art surfaces

The rock art of the Kimberley region is an example of Australia's rich aboriginal cultural heritage. The rock surfaces are living canvasses of ancient mineral-organic pigments and modern microbial biofilms. We seek to understand the potential impacts - preservative or destructive - of the microbial community on rock art surfaces, focusing on potential microbe-mineral redox reactions controlling the form and fate of iron or manganese.

Limits of microbial habitability in the marine deep biosphere

Anaerobic methane-oxidizing (AOM) microbial consortia significantly limit the flux of methane (a greenhouse gas) from the seafloor to the atmosphere.  As part of IODP Expedition 322, we have been investigating a very deep (~420 meters below seafloor) sulfate-methane transition zone and potential AOM consortium in the Nankai Trough Subduction Zone (Japan).  Our aim is to understand the effects of deep recirculation of seawater, which allows sulfate to move upwards through the basement-sediment interface and persist as an electron acceptor for microbial methane consumption in the deepest part of the sediments.

Deciphering the evolution of microbial arsenic resistance

If life evolved in hot springs or hydrothermal vents, the earliest microorganisms must have possessed some mechanism of resistance to the toxic metalloid arsenic.  We are studying the diversity of prokaryotic arsenic resistance mechanisms in Champagne Pool, New Zealand, an early Earth analog environment, to try to understand the origin and evolution of microbial arsenic resistance.