Alteromonas macleodii MIT1002 growth on and uptake of Prochlorococcus-derived metabolites

This data package contains the results from a series of experiments designed to test the response of a heterotrophic, copiotrophic, gammaproteobacterium, Alteromonas macleodii strain MIT1002, to a range of metabolites released by the phytoplankton Prochlorococcus. A. macleodii MIT1002 was isolated from co-culture with Prochlorococcus, and so we hypothesized that A. macleodii MIT1002 would be able to grow on the full range of substrates tested. Instead, we found that A. macleodii MIT1002 could only grow on a narrow range of substrates, and data suggest that this substrate specificity may be related to transporter specificity.

We performed two types of experiments: growth experiments and uptake experiments. Data from growth experiments are labeled with the name of the substrate being tested (e.g., “Leu,” for leucine, or “3m2ob”, for 3-methyl-2-oxobutanoic acid). For these experiments, we grew A. macleodii MIT1002 on either pyruvate (as a positive control), a selected Prochlorococcus-related substrate, or a mix of pyruvate and the metabolite. We measured growth in 96-well plates by OD600 using a plate reader which took a measurement every 0.5h for 48h. Uptake experiments are labeled with either “KHU7” (an experiment which tested A. macleodii MIT1002 growth on and uptake of 3-methyl-2-oxobutanoic acid) or “KHU8” (an experiment which tested the A macleodii MIT1002 growth on and uptake of 3-methyl-2-oxopentanoic acid -or lack thereof). For these experiments, we measured growth by flow cytometry. We measured the change in dissolved (i.e., extracellular) metabolite concentration by filtering samples, extracting organic carbon from the filtrate by solid phase extraction, and quantifying selected metabolites from the filtrate by targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS). This data package includes the peak areas for targeted metabolites generated by LC-MS/MS, the peak areas for our standard curves used for quantification, and the dissolved metabolite concentrations quantified by this analysis. These experiments (both growth and uptake) were performed from January 2019 – June 2021, and this is a completed data package.