Award: OCE-1220484

This project contributed to our understanding of the influence of multiple stressors on phytoplankton in the oceans using a new protein quantitation technique known as targeted metaproteomics. Experiments studied the influence of CO2, iron, temperature, cobalt, and zinc in cyanobacteria, Phaeocystis and diatom phytoplankton. A novel zinc transporter identified in diatoms in cobalt-zinc substitution experiments. Iron stress in Phaeocystis was shown to be a trigger for colony formation and the colony microbiome harbored bacteria capable of iron storage and vitamin B12 biosynthesis. Experiments with varying CO2 and Prochlorococcus cultures showed a response in iron-stress proteins, implying the use of ferrous iron by this abundant microbe. The proteins identified in laboratory experiments to have specific responses to environmental stimuli were then be used as biomarker indicators for processes in the oceans (e.g. nutritional scarcities). Protein responses that were targeted included those that were specific to environmental stressors, including urea transporters and global nitrogen regulatory systems for nitrogen scarcity, and iron transporter components and flavodoxin (iron-free electron carrier proteins) for iron scarcity in marine cyanobacteria. The new proteomic method, named "targeted metaproteomics" was deployed in the Pacific Ocean and observed large scale gradients of biomarkers that corresponded to gradations in nutrient and micronutrient availability, demonstrating its potential application as a global scale ocean diagnostic tool for understanding ocean chemistry and biology on ocean sections and time series. Last Modified: 11/30/2016 Submitted by: Mak A Saito