Time & Energy: Fundamental microbial mechanisms that control CH4 dynamics in a warming Arctic

Microorganisms use a large number of different energy sources, are adapted to various chemical conditions and are exposed to major changes in temperature, water and available energy throughout the seasons and as a result of climate change. How individual organisms and complex microbial communities adapt to their environment in the short and long term are the basic knowledge needed to understand their role in ecosystems and change in behavior as a result of climate change. In this project we try to understand how microbes with key roles in the global methane and carbon cycle have found their role in the environment and adapt to changes over time, and how this relate to the concentration of greenhouse gases in the atmosphere. The project takes place in four parallel races, each part focussing on an aspect of microbial ecology where important knowledge gaps limit our understanding of nature: 1: The Energetically Restrictive Step in Methane Production - Synthrophy - We look at how organisms living on a diet at the energetic limit of life react to temperature changes over time. This is important for our understanding of the link between climate change and methane production in Arctic peat. 2: Low concentrations of greenhouse gas methane in the atmosphere can only be broken down by a special group of bacteria that live with greatly limited energy availability, making them a key group in the methane cycle. Isolates of this group have not been available until now. We look at the evolution, cell biology and metabolism of one of the most important groups of bacteria in the subject of climate change. 3: Large amounts of carbon are stored in soil. Recently, scientists have found that warming over time (10-50 years) leads to a reduction in the amount of carbon stored in soil before a new balance is established with a smaller microbial biomass. We look at the adaptations that occur in microbial communities in unique land-heating attempts in Iceland, which were started more than 50 years ago. 4: The relationship between plants and microorganisms that live on or within plants and in the soil beneath them is fundamental to the global carbon cycle. Mosses, grasses and Carex species are among the most important contributors to the large carbon stocks of peat in Arctic and temperate areas. These peats are threatened by degradation and resulting increases in greenhouse gas emissions as a result of climate change. We look at how different peat bogs are associated with different groups of bacteria and how this is related to the evolution of such ecosystems in the short and long term. We also study how changes in the populations of grazing animals and altered vegetation composition affects the soil microbes and their activities.

Prosjektet vil medføre en økt forståelse for hvilke typer mikroorganismer er viktig for den globale metan og karbonsyklus. Spesielt fokus er på mikroorganismer som er en del av naturens respons på klimaendringer i Arktis.

Syntrophic bacteria and their methanogenic partners live at the energetic limit for microbial growth, and are therefore extremely sensitive to changes in their environment. These anaerobic microorganisms are responsible for the last step in the degradation of organic matter to methane (CH4) and CO2 in Arctic peat soils, and has been shown to be the bottleneck for CH4 production at low temperatures in these soils. The Arctic and sub-Arctic peatlands are exposed to temperature changes within and between seasons. Thus, the actual effect of a warmer climate on the carbon balance might be dependent on microbial responses to higher temperatures at timescales ranging from short(hours) to intermediate(weeks) and long(months). In this project I will explore temperature effects on microbial metabolism, microbial populations and microbial trophic networks in time series experiments to determine the speed of adaptation. Peat soils from Arctic Svalbard and sub-Arctic Northern Norway will act as model-systems as they represent two different levels of low-temperature adaptation. This project is extremely timely because it capitalises upon the recent developments in genome-centric metagenomics. With current methods it is possible to assemble high quality draft genomes from metagenomes, which act as a databases for assigning microbial transcripts to specific species within key functional guilds. Thereby we can track changes in the transcriptional activity of key species, corresponding metabolite fluxes and CH4 production over time to identify the dynamics of essential microbial mechanisms. The project is also important due to the rising Arctic temperatures and uncertain fate of large Arctic carbon stocks. Fundamentally it seeks to provide new insights into how complex microbial communities have evolved to respond to perturbations. Specifically, it seeks to explain how and how fast the syntrophic bottleneck reacts to changing temperature, and what effect this has on CH4 production.