Biography

  Dr. Satoshi Ishii is a full Professor in the Department of Soil, Water, and Climate and the BioTechnology Institute at the University of Minnesota Twin Cities. His research aims to address environmental challenges through the application of microbiology and biotechnology. His recent work focuses on three major areas: 1) bioremediation of nutrient pollution; 2) the ecology of pathogens and antibiotic-resistant bacteria in soil and water environments; and 3) microbial community responses to environmental change. Dr. Ishii’s research group integrates microbiological, analytical, molecular biological, omics-based, and engineering approaches to address both fundamental and applied questions in environmental microbiology. His work has been published in leading journals in the field, including The ISME Journal, Microbiome, Environmental Science & Technology, and Water Research. Dr. Ishii received the Young Investigator Award from the Japanese Society of Microbial Ecology in 2015 and the 3M Non-Tenured Faculty Award in 2018. He currently serves as a Senior Editor for Microbes and Environments and as an Editor of Applied and Environmental Microbiology.

Abstract

  Cryoconites are microbial aggregates commonly found on glacier surfaces where they tend to take spherical, granular forms. Cryoconites can decrease surface albedo and accelerate the melting of snow and ice, thereby influencing the glacier mass balance. Our research over the past 15 years has clarified the role of glacier cryoconites in carbon and nitrogen cycling in glacier ecosystems. Based on microbial community analysis, metagenomics, metatranscriptomics, stable isotope analysis, microsensor analysis, and microscopic analysis, we revealed that cryoconites are hotspots for microbial nitrification and denitrification. The primary producers in cryoconites are filamentous Cyanobacteria. In large cryoconite granules, Cyanobacteria in the inner core of the granules are inactive and being degraded. This area is more anoxic than the surface layer. Organic N from dead cyanobacterial cells is likely used for nitrification and denitrification. This pattern is, however, not universal across cryoconites on different glaciers. Genes related to nitrification and denitrification are more abundant in the cryoconites on high mountain glaciers in Asia than those on polar glaciers. These findings deepen our understanding of the biodiversity and biogeochemical cycles of glacier ecosystems, which are susceptible to ongoing climate change and glacier decline, on a global scale.