Special seminar - Jeffrey Blanchard: Giant Viruses, Chlamydia, Vampire Bacteria and the Unexpected Diversity in Soil Microbial Life in the Harvard Forest Experimental Warming Plots

Abstract:

The Harvard Forest Long Term Ecological Research site in Petersham, MA is home to long-term experimental soil warming sites heated continuously to 5° C above ambient since 1991 and 2001, ample time for natural selection of genotypes better adapted to the altered environment. To better understand microbial biodiversity and develop a reference database for read mapping, we used a variant of single cell sequencing with small poosls of cell to improve cost efficiency. Phylogenomic analysis revealed a surprising diversity of microbial life. Sixteen new lineages of giant viruses were discovered for the first time in a forest soil ecosystem. Intracellular and host-dependent bacteria were enriched in the data set relative to abundances in our traditional metagenomics data set of DNA extracted directly from the soil. This collection of mini-MAGs exposed a reservoir of genetic diversity in difficult to cultivate organisms, some of which are related to human pathogens.