Genotyping microbial life forms in Antarctic sea ice

Abstract

Each year, an area of sea ice, approximately 19 million km2, forms around the continent of Antarctica and becomes inhabited by a complex of microbial communities. It is recognised that these communities contribute to a large proportion of the total Southern Oceans biomass when the sea ice melts in summer. However, little is known about the sea ice microorganisms that generate this biomass. The aim of this project is to determine the identity of the microbial components of the sea ice ecosystem and enhance our understanding of the biomass generating process which occurs in Antarctic sea ice. The experimental approach entails the isolation of total community DNA from the sea ice cores and profiling these communities by Restriction Fragment Length Polymorphism (RFLP). PCR amplification and the subsequent sequencing of established markers of microbial phylogeny, the 16S and 18S ribosomal RNA genes, using combinations of published primer sets as well as targeted primer sets has enabled the identification of a number of microbial species. Some of the organisms that we have detected have been described in previous literature, while others have not. To date the most dominant microbial species present in the sea ice belong to the Alpha and Gamma divisions of Proteobacteria as well as organisms from the Cytophaga Flavobacterium Bacteroides (CFB) division. The information gathered will provide a basis for the generation of an improved model of primary productivity in Antarctic sea ice. In addition, this project will contribute data to the Latitudinal Gradient Project funded by Antarctica New Zealand.