Fig. 3
Cobetia sp. MC34 and Cobetia marina DSM 4741T are mesophilic and produce PHB and PHBV. A Cobetia sp. MC34 (blue) and C. marina DSM 4741T (orange) showed highest growth rate and putative PHA production per hour measured by FT-IR (visualized by sphere area) at 30 °C in 5 mL MMCY media supplemented with 2% glucose. The error bars show coefficient of variation of the specific growth rate between duplicate experiments (n = 6). B Growth curves in 80 mL MMCY and MMCY_2 media supplemented with 2% sodium acetate and 1.5% glycerol, respectively, at 30 °C, 200 rpm. The putative PHA production was measured by FT-IR (visualized by sphere area). The error bars show the coefficient of variation of the OD600 between duplicate experiments (n = 6). C FT-IR spectra of cells grown in 80 mL MMCY_2 media supplemented with 2% sodium acetate at 30 °C, 200 rpm for 28 h (C. marina DSM 4741T) and 32 h (Cobetia sp. MC34). The carbonyl-ester peaks at wavenumber 1724 cm−1 (arrows) indicate PHA production, and high amounts of PHB was confirmed by GC-FID analysis. D NMR confirms PHBV production in Cobetia sp. MC34. When grown on MMCY_2 media supplemented with 20 g/L sodium acetate, 3-HB were produced as indicated by peaks 1, 2 and 3 in the proton 1H plot (negative control) and peaks 1, 2, 3 and 4 in the carbon 13C plot (negative control). Co-supplement with 8 mM sodium valerate resulted in peaks unique to 3-HV as indicated by 5, 7, and 8 in the 1H plot and 5, 6, 7, 8, and 9 in the 13C plot. The spectra were normalized to the non-solvent peak with the highest intensity