Lotta Purkamo

• PhD
• Senior Researcher at Geological Survey of Finland

The emerging interest in using stable bedrock formations for industrial purposes, e.g., nuclear waste disposal, has increased the need for understanding microbiological and geochemical processes in deep crystalline rock environments, including the carbon cycle. Considering the origin and evolution of life on Earth, these environments may also serve...

The bacterial and archaeal community composition and the possible carbon assimilation processes and energy sources of microbial communities in oligotrophic, deep, crystalline bedrock fractures is yet to be resolved. In this study, intrinsic microbial communities from groundwater of six fracture zones from 180 to 2300 m depths in Outokumpu bedrock w...

Due to their potential to support chemolithotrophic life, relic hydrothermal systems on Mars are a key target for astrobiological exploration. We analysed water and sediments at six geothermal pools from the rhyolitic Kerlingarfjöll and basaltic Kverkfjöll volcanoes in Iceland, to investigate the localised controls on the habitability of these syst...

The retreat of glaciers in response to climate change has major impacts on the hydrology and ecosystems of glacier forefield catchments. Microbes are key players in ecosystem functionality, supporting the supply of ecosystem services that glacier systems provide. The interaction between surface and groundwaters in glacier forefields has only recent...

The impact of submarine groundwater discharge (SGD) on coastal sea biogeochemistry has been demonstrated in many recent studies. However, only a few studies have integrated biogeochemical and microbiological analyses, especially at sites with pockmarks of different degrees of groundwater influence. This study investigated biogeochemical processes a...

The growth and metal enrichment of ferromanganese minerals on the seafloor have intrigued many studies, yet the role of microbes in the process has remained elusive. Here, we assessed the microbial influence on the growth and trace metal accumulation and release of ferromanganese concretions from the Baltic Sea using 12‐week microcosm incubation ex...

The fluids at black schist-rich bedrock in the Fennoscandian shield have been shown to carry extensive methane (Kietäväinen and Purkamo 2015, Kietäväinen et al. 2017). The sources of methane, abiotic, microbial, thermogenic, or their mixtures, are not well understood (Etiope and Sherwood Lollar 2013, Douglas et al. 2017). While previous field and l...

The thin layer known as the Earth’s crust contains an even thinner layer that is suitable for sustaining life. The boundary conditions that define where we can find life in the deep subsurface depend on the physical space and water availability, accessibility to suitable substrates for energy and growth, in addition to tolerable temperature and pre...

While recent efforts to catalogue Earth’s microbial diversity have focused upon surface and marine habitats, 12–20 % of Earth’s biomass is suggested to exist in the terrestrial deep subsurface, compared to ~1.8 % in the deep subseafloor. Metagenomic studies of the terrestrial deep subsurface have yielded a trove of divergent and functionally import...

The deep terrestrial biosphere hosts vast sessile rock surface communities and biofilms, but thus far, mostly planktic communities have been studied. We enriched deep subsurface microbial communities on mica schist in microcosms containing bedrock groundwater from the depth of 500 m from Outokumpu, Finland. The biofilms were visualized using scanni...

Spent nuclear fuel will be deposited in deep geological repositories in the crystalline bedrock in Finland and Sweden. The repositories rely on the multi-barrier KBS-3 concept, where the first barriers consist of copper-sheeted cast-iron canisters that contain the spent nuclear fuel rods. However, the repositories will be influenced by both abiotic...

Fungi have an important role in nutrient cycling in most ecosystems on Earth, yet their ecology and functionality in deep continental subsurface remain unknown. Here, we report the first observations of active fungal colonization of mica schist in the deep continental biosphere and the ability of deep subsurface fungi to attach to rock surfaces und...

This study examines the effect of poly-aluminium chloride (PACl) pre-treatment on the biological purification process taking place during managed aquifer recharge (MAR). PACl treatment is used in waste and surface water treatment to remove organic material. PACl can decrease the organic carbon contents of water significantly. However, aluminium is...

The deep bedrock surroundings are an analog for extraterrestrial habitats for life. In this study, we investigated microbial life within anoxic ultradeep boreholes in Precambrian bedrock, including the adaptation to environmental conditions and lifestyle of these organisms. Samples were collected from Pyhäsalmi mine environment in central Finland a...

The Neogene and Quaternary are characterized by enormous changes in global climate and environments, including global cooling and the establishment of northern high-latitude glaciers. These changes reshaped global ecosystems, including the emergence of tropical dry forests and savannahs that are found in Africa today, which in turn may have influen...

While recent efforts to catalogue global microbial diversity have focused upon surface and marine habitats, 12% to 20% of terrestrial bacterial and archaeal biomass is suggested to inhabit the terrestrial deep subsurface, compared to ~1.8% in the deep subseafloor. Metagenomic studies of the terrestrial deep subsurface have yielded a trove of diverg...

The deep biosphere contains a large portion of the total microbial communities on Earth, but little is known about the carbon sources that support deep life. In this study, we used Stable Isotope Probing (SIP) and high throughput amplicon sequencing to identify the acetate assimilating microbial communities at 2260 m depth in the bedrock of Outokum...

The diversity and metabolic functions of deep subsurface ecosystems remain relatively unexplored. Microbial communities in previously studied deep subsurface sites of the Fennoscandian Shield are distinctive to each site. Thus, we hypothesized that the microbial communities of the deep Archaean bedrock fracture aquifer in Romuvaara, northern Finlan...

Duncan Forgan, Lotta Purkamo and Ashley Watkins relate what lessons they learned by kick-starting interdisciplinary collaboration with cake.

Microbial communities in deep subsurface environments comprise a large portion of Earth's biomass, but the metabolic activities in these habitats are largely unknown. Here the effect of CO2 and carbonate on the microbial community of an isolated groundwater fracture zone at 180 m depth of the Outokumpu Deep Scientific Drill Hole (Finland) was teste...

The Fennoscandian Shield in Finland dates back to the Archaean and Proterozoic eons, and hosts ancient fluids (> 50 million year old) and thriving microbial life, but little is known about the limits of life in this harsh environment. Our project aims to explore the adaptability and metabolic potential of the deep biosphere by defining the features...

Acetate plays a key role as electron donor and acceptor and serves as carbon source in oligotrophic deep subsurface environments. It can be produced from inorganic carbon by acetogenic microbes or through breakdown of more complex organic matter. Acetate is an important molecule for sulfate reducers that are substantially present in several deep be...

The Fennoscandian crystalline bedrock fractures host microbial communities with versatile features. These communties thriving in isolated environments are possibly forming the oldest known ecosystems on Earth, as they are are likely as old as the fracture fluids, up to 58 Ma [1]. Low cell numbers but high diversity is characteristic to the microbia...

Microbial life in the deep subsurface contributes significantly to overall biomass on Earth. Although the microbial communities inhabiting the deep subsurface are abundant, little is known about their diversity, activity, interactions and role in global biogeochemical cycles. The diversity of microbial life in the deep terrestrial subsurface of the...

The bacterial and archaeal community composition and the possible carbon assimilation processes and energy sources of microbial communities in oligotrophic, deep, crystalline bedrock fractures is yet to be resolved. In this study, intrinsic microbial communities from six fracture zones from 180–2300 m depths in Outokumpu bedrock were characterized...

The current surface conditions on Mars are inhospitable for living organisms. The subsurface of Mars on the other hand can be a potential spot for detecting extraterrestrial life. Groundwater brines are suggested to support life on Mars, thus research on analogue environments on Earth such as deep, ancient, oligotrophic and saline bedrock fluids ca...

The DeepHotMicrobe project aims to determine the limits of life in ultra deep terrestrial crystalline bedrock and to describe the environmental factors restricting the existence of microbial life at these depths. How deep can we go and still find active microbial life in the fracture fluids of crystalline bedrock? Are there isolated microbial commu...

The deep carbon cycle is controlled by combination of hydrogeochemical and biological processes. Methane is the most abundant gas in Outokumpu bedrock and a 2516 m deep scientific drill hole at the site provides an ideal location to study methane cycling in crystalline biosphere. Methanogenesis is the final step in decomposition of organic matter a...

Deep crystalline bedrock fractures in Outokumpu, Finland, host diverse microbial communities. The fracture zones filled with tens of millions of years old fluids represent unique environments, where indigenous microbial communities exist. The next-generation sequencing of the 16s rRNA gene of bacteria and archaea revealed the structure of these mic...

Indigenous microbial communities of six fracture zones and mixed communities from five depths of the water column of Outokumpu Scientific Drill Hole in Finnish bedrock were studied with pyrosequencing. In addition to 16S rRNA gene based characterization of bacterial and archaeal 6 community structures, functional marker genes for sulphate reduction...

The deep subsurface hosts diverse life, but the mechanisms that sustain this diversity remain elusive. Here, we studied microbial communities involved in carbon cycling in deep, dark biosphere and identified anaerobic microbial energy production mechanisms from groundwater of Fennoscandian crystalline bedrock sampled from a deep drill hole in Outok...

Deep bedrock fluids host abundant microbial communities. Deep-dwelling microbes utilize inorganic carbon sources, such as methane, which is abundant in deep subsurface environments, or carbon dioxide. Due to the prevailing anaerobic conditions, sulphate or nitrate are possible terminal electron acceptors. However, only 1-5 % of these microbes are c...

Saline fluids in crystalline bedrock fractures host diverse microbial communities. Unique ecosystems can exist in rock environments that have been isolated for millions of years. The Outokumpu Deep Drill Hole in Eastern Finland spans 2516 m in Precambrian bedrock and has several fracture systems at different depths. Microbial communities from the d...

Deep fracture zones in Finnish crystalline bedrock have been isolated for long, the oldest fluids being tens of millions of years old. To accurately measure the native microbial diversity in fracture-zone fluids, water samples were obtained by isolating the borehole fraction spanning a deep subsurface aquifer fracture zone with inflatable packers (...

In deep subsurface environments, carbon is available as CH4, CO2 or other small carbon molecules, such as acetate. The goal of the study was to enrich acetate consuming microbial communities from indigenous fracture fluid attained from a Finnish crystalline bedrock groundwater system. Samples were collected from Outokumpu deep borehole from a depth...