University Honors

Soil microbiomes are formed from a diverse community of bacteria, fungi, archaea,protozoa and other types of microorganisms. These microscopic organisms play crucial roles insoil health, nutrient cycling, gas exchange, and overall ecosystem functioning. Soil microbialcommunities are capable of decomposing organic matter, detoxifying toxic substances, andfixing nitrogen. Surface soils differ from subsurface soils, in their pH, texture, moisture, redoxreactions, and nutrient concentrations. This project aims to explore how microbial communitieschange in response to soil depth in the “Nivolet Critical Zone” field site, in Gran ParadisoNational Park, Italy. We hypothesized that microbial communities will change with soil depth,and that dominant taxa would include Chloroflexi, Nitrospirae, and Euryarchaeota and parentmaterial would heavily influence microbial diversity within sites. Soil pits were dug in a range ofsites with variable bedrock parent materials and positions on the slope. Samples were collected ata range of depths for microbial community and other analyses. Soils were frozen within 24 hoursof sampling and maintained frozen during transport from Italy to Riverside, CA in the USA. Soilsample microbial DNA was extracted and purified, followed by Polymerase Chain Reaction(PCR) amplification of the V3 and V4 region of 16S rRNA. Results show that alpha diversitysignificantly varies by depth increment across sites, however alpha diversity does not vary bysite. Beta diversity shows that the overall microbial community vary significantly by site. Thisindicates that parent material and depth has a huge influence on microbial diversity and relativeabundance. This helps to understand the diverse biological, microbial and ecological diversity ofsoil depths.