Fig. 1: Monitoring of growth and substrate utilization in microcosms amended with either 12C-natural (blue) or 13C-enriched alginate (red), or in unamended controls (grey).

Cell abundance was measured by flow cytometry (circles and plain lines, left axis). Alginate consumption was measured as the percentage of added uronic acids that remained in microcosms over time (diamonds and broken lines, right axis). Values are mean ± s.e.m. (n = 3).