RT Journal Article SR Electronic(1) A1 Hallbeck, Lotta A1 Pedersen, KarstenYR 1991 T1 Autotrophic and mixotrophic growth of Gallionella ferruginea JF Microbiology, VO 137 IS 11 SP 2657 OP 2661 DO https://doi.org/10.1099/00221287-137-11-2657 PB Microbiology Society, SN 1465-2080, AB Summary: CO2 fixation and uptake of sugars by Gallionella ferruginea were demonstrated by liquid scintillation and microautoradiographic techniques. The theoretical carbon content of a G. ferruginea cell in the exponential and stationary growth phases was calculated from size measurements of images of acridine-orange-stained cells. The carbon content of a cell in the exponential phase was 1·25 × 10−14 mol and for a cell in the stationary phase it was 5 × 10−15 mol. G. ferruginea was shown to obtain all of its cell carbon from CO2 fixation when it was cultured under aerobic gradient conditions in a mineral salt solution with iron sulphide. Uptake experiments were performed with 1·6 μM-[14C]frucose, 1·6 μM-[14C]fructose and 1·3 μM-[14C]sucrose. There was significant uptake of all three sugars. Measurements of respired 14CO2 showed that 48%, 25% and 32% of the total amount of incorporated sugar was respired for glucose, fructose and sucrose, respectively. The uptake of glucose increased when the glucose concentration in the growth medium was increased. At a glucose concentration of 10 μM or higher, the cell carbon was derived exclusively from glucose, within the errors of estimation. Mixotrophic growth with 20 μM-glucose decreased the CO2 fixation to 0·4 × 10−14 mol carbon per cell, compared to autotrophically grown cells with 1·0 × 10−14 mol carbon per cell. The addition of 20 μM-glucose gave an increase in cell number in the stationary phase from 1 × 106 to 5 × 106 cells ml−1., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-137-11-2657