TABLE 1.

Contribution of CO₂ to protein carbon in cells of the magnetotactic coccus strain MC-1 grown in semisolid, oxygen-gradient medium containing 10 mM thiosulfate as the electron source and ¹⁴C-bicarbonate/CO₂ as the sole carbon source^a

Total CO2 fixed (μg of C)b	CO2 incorporation (protein fraction [μg of C])	Total cell protein (μg)	Total protein carbon (μg of C)c	% Protein carbon from CO2d	% Recovery of radiolabel
27.4 ± 1.3	7.26 ± 0.82 (26.5 ± 2.9%)e	13.4 ± 1.3	7.26 ± 0.70	99.9 ± 2.5	82.6 ± 2.9

^aResults are reported as means ± standard deviations derived from triplicate cultures.

^bCO₂ fixation in uninoculated tubes was virtually undetectable, and counts from all fractions of uninoculated controls never exceeded 50 cpm and were subtracted from counts.

^cComputed from total cellular protein times 54%, the average carbon content of protein (wt/wt) from Doolittle (16) and Jukes et al. (32).

^dCalculated as follows: 100% × μg of C incorporated into protein fraction/calculated total protein C.

^eC incorporated from CO₂ into protein fraction as a percentage of total CO₂ fixed.