Figure 1

I n situ phenotypic heterogeneity in substrate assimilation by ‘Ca. M. parvicella’. (a) Overview of the four independent isotopic incubation experiments. All experiments were conducted at 25 °C, except for the temperature-dependent experiment for which various temperature ranges were used. (b) Fluorescence in situ hybridization (FISH) with a ‘Ca. M. parvicella’-specific probe followed by atomic force microscopy (AFM) imaging to verify cellular integrity among ‘Ca. M. parvicella’ cells. (c) The same region was analyzed using nanoSIMS to obtain ¹³C-isotopic enrichment information. AFM and nanoSIMS images were overlayed to highlight the distribution of newly assimilated substrates among ‘Ca. M. parvicella’ cells. Regions of interest around individual ‘Ca. M. parvicella’ cells were defined manually using the corresponding FISH images and their corresponding ¹³C atomic percentages were subsequently calculated. (d) ¹³C-oleic acid assimilation at different time points under either aerobic or anoxic conditions. (e) Temperature-dependent aerobic assimilation of ¹³C-oleic acid by single cells of ‘Ca. M. parvicella’ after 5 h of incubation. (f) ¹³C-glycerol-3-phosphate assimilation under aerobic or anoxic conditions when administered as a single substrate. (g) Assimilation of ¹³C-oleic acid following alternating aerobic–anoxic conditions. (d–g) The dotted line indicates the ¹³C atomic percentage of ‘Ca. M. parvicella’ single cells from time point 0 h.