EAPSI: Defining Resource Preferences of Single Cells from Aquatic Microbial Communities using Raman Microspectroscopy

Kieft Brandon P, Corvallis OR

Investigators

Abstract

This research project will determine the microbial populations that are consuming amino acids in Osaka Bay and Muko River, Japan. This objective will be accomplished using Raman microspectroscopy to measure cells that have taken amino acids from the environment and used them for growth. Dissolved amino acids are an important organic matter source for both energy and biomass production in aquatic microorganisms, thus, turnover and recycling of this substrate by microbes is a critical step in the carbon cycle of coastal margins around the world. This research will be conducted in collaboration with Dr. Shinsuke Shigeto, a noted expert in biological and chemical analysis using Raman spectroscopy, at Kwansei Gakuin University in Kobe, Japan. Few laboratories are equipped with a Raman microspectrometer set up to scan living biological cells, thus this collaboration represents a unique opportunity to combine the expertise of the project PI and the Japanese collaborator. This research project will measure the incorporation of 13C-labeled amino acids (AAs) into the biomass of single bacterioplankton cells in natural microbial communities from Osaka Bay and the Muko River, Japan. This objective will be accomplished using a combination of stable isotope probing, fluorescence in-situ hybridization, and Raman microspectroscopy. After incubating communities with 13C-labeled AAs, incorporation of the isotope into biomass of individual cells from dominant populations will be measured by a ?red-shift? of the phenylalanine peak in their Raman spectra. This study will develop a non-destructive technique to identify single cells from a natural microbial community that utilize a specific substrate. Prokaryotic 16S rRNA gene amplicons will also be sequenced before and after incubations to correlate community-level data with population- and single-cell level AA incorporation data. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.