Fig. 4: D. alkaliphilus grows autotrophically with ferrihydrite and sulfide or FeS.
From: Microbial iron oxide respiration coupled to sulfide oxidation
a, Mean cell density (n = 3) increased significantly (P = 2.18 × 10−8; ANOVA) over 4 days of incubation with ferrihydrite and daily addition of sulfide (1 mM). b, Mean cell density (n = 3) increased significantly (P = 3.79 × 10−10; ANOVA) over 13 days of incubation with ferrihydrite and periodic spikes of FeS (approximately 1 mM). c, Mean cell density (n = 3) increased significantly (P = 1.84 × 10−8; ANOVA) over 5 days of incubation with ferrihydrite and periodic addition of approximately 50 µM sulfide. d, Mean cell density (n = 3) increases significantly (P = 5.53 × 10−11; ANOVA) alongside sulfide consumption over 3 days of incubation with sulfide and nitrate (4 mM). e, Bulk 13C abundance (atom%) increased (P = 2 × 10−4; ANOVA) over 6 days in living cultures (n = 3; orange circles) incubated with 10% 13C-bicarbonate, ferrihydrite, and daily addition of sulfide (1 mM). f, Bulk 13C abundance increased (P = 0.003; ANOVA) over 6 days in living cultures (n = 3) incubated with 10% 13C-bicarbonate, ferrihydrite, and two spikes of FeS (approximately 1 mM). e,f, Asterisks denote significant differences (P < 0.05; two-sided Student’s t-test) on day 6. Dashed lines indicate natural 13C levels. a–f, Arrows indicate sulfide or FeS addition. g,h, Nano-scale secondary ion mass spectrometry (NanoSIMS) images showing cellular biomass (g; 12C14N–) and 13C content (h) of cells at day 0 and 5. Colour scale refers to 13C atom%. Scale bars correspond to 5 μm. i, Dot plots displaying the 13C content of individual cells analysed in a representative NanoSIMS field view at day 0 (n = 81 cells) and 5 (n = 80 cells). Box plots show the median, the 25th and 75th percentiles of 13C content of cells; whiskers extend to 1.5 times the interquartile range from the first and third quartiles.
