The role of trace gas oxidising bacteria in soil recovery of burned environments

Lead Supervisor: Dr Marcela Hernandez Garcia

Location: University of East Anglia, Biological Sciences

Duration: 6 weeks

Suitable undergraduate degrees: Environmental Microbiology

Project background

Wildfires release significant amounts of trace gases such as carbon monoxide (CO) and isoprene (a volatile organic compound (VOC)) into the atmosphere posing health risks to both humans and wildlife1,2. In addition to the toxic effects, many VOCs contribute to climate change. Therefore, understanding and quantifying trace gas emissions from fires is essential for assessing their environmental and public health impacts.
During February 2-6, 2024, wildfires ravaged thousands of homes in in Viña del Mar, Chile. The wildfires also destroyed >90% of Chile’s national botanical garden in Viña del Mar. The site was a 395-ha garden with more than 1000 tree species, and one of the world’s largest gardens. Not only was the botanical garden a crucial conservation and research centre for the region, but it was believed to have an important role for air quality in the region and acting as a sink for VOCs3.
Healthy soils are diversity hotspots containing up to a billion microbes and thousands of species per gram, including trace-gas oxidising bacteria. Therefore, we believe there is an urgent and unique opportunity to determine if the soils – and their microbes – at the Botanical Garden continue to act as a sink for trace gases (including VOCs). Our goal is to identify adaptation mechanisms of the microbial community against the presence and degradation of recalcitrant organic matter produced in fires. We also aim to explore whether there is an opportunity to steer their recovery, for example by the addition of organic material (e.g., compost). Early studies have shown that organic amendments can increase soil atmospheric methane uptake in agricultural soils4. However, whether this effect is similar in burned environments remains to be investigated.

Objectives
The main objective for this summer secondment is to analyse whether there is a microbial metabolism of trace gases, including VOCs,

Methodology
Sampling. Sampling campaigns will be performed before the start of this project at the Botanical Garden with the help of our collaborators in Chile. Unburned soils from a garden located next to the burned garden will be used as a control. Samples will be shipped to UEA immediately after the sampling campaign.
qPCR. DNA will be extracted using standard extraction kits and total 16S rRNA gene will be used to quantify both bacteria and archaea. 16S rRNA sequencing will also be performed to identify the total microbial community from those sites.
Degradation/consumption assays. 10 g of soil (with or without pyrogenic material) will be incubated in 120-ml vials. Trace gases (e.g. CO) will be added to the headspace of the vial, sealed using butyl rubber stoppers and aluminium crimp caps, and consumption will be monitored over time using by gas chromatography.

References
[1] Ciccioli et al 2014. Plant Cell Environ 37:1810-1825.
[2] Gilman et al. 2015. Atmos Chem Phys 15:13915-13938.
[3] Segel et al. 2023. Environ Pollut 330:121759.
[4] Brenzinger et al. 2021. Biol Fertil Soils 57:1053-1074.