PNNL

Abstract

Over the last several decades there has been a steady rise in the amount of CO2 in the atmosphere leading to increased climate changes. Alongside efforts to reduce carbon output there has also been a focus on using the soil environment as a means of carbon sequestration and long- term storage (Bhattacharyya et al. 2022). Soil represents a large potential sink with the capacity to store up to 80% of terrestrial carbon (Lal 2004). In addition, soils that have been used for agriculture are often depleted of carbon, meaning they are well suited to act as new carbon sinks for sequestered carbon (Paustian et al. 1997). While some effort has been made toward using plants as a means of carbon storage (via CO2 capture and movement to below ground biomass) there has been less focus on using soil microbial communities directly to cycle carbon and store it either as microbial necromass or as forms of precipitated carbon. Driving microbial soil communities to store carbon in this way may lead to more stable carbon sinks as well as the advantage of working with multiple types of carbon inputs. Once developed, such carbon sequestering soil communities could also be paired with photosynthetic components to pull CO2 directly from the atmosphere for storage. The CarbStor project is focused on developing, analyzing and modifying defined microbial soil consortia that express phenotypes at both the species and community level to convert carbon into recalcitrant stable sources such as precipitated carbonate or microbial necromass. To take full advantage of the soil community for this process we will need to fill several key knowledge gaps (KG), three of which are the focus of CarbStor. KG1: Whether and to what degree microbial communities can be developed that produce precipitated carbon via microbial metabolism. KG2: What interspecies interactions drive the individual member phenotypes in defined communities that lead to carbon precipitation. KG3: How can these interactions be modified to enhance carbon sequestration beyond what native communities are capable of. We hypothesize that in a carbon sequestering community only a subset of species will express phenotypes related to carbon storage processes. We also hypothesize that these phenotypes are expressed as a result of interactions with other species in the community that are not involved in carbon storage processes and that these interactions can be harnessed to enhance community carbon sequestration.