FIG. 4.

(A to D) Effect of sodium cycling on major fermentation product yields from A. maxima filaments under autofermentative conditions for 0 to 2 days. Filaments were grown in Zarrouk's medium with an additional 0.00, 0.25, 0.50, 0.75, or 1.00 M NaCl; subsequently, filaments were resuspended in 210 mM sodium (bi)carbonate buffer, pH 9.8, and incubated under dark anaerobic conditions to induce osmotic stress (see Materials and Methods). The cells underwent autofermentation to produce hydrogen (A), ethanol (B), acetate (C), and formate (D). Lactate was only a minor fermentative product and was never detected in amounts higher than 150 μmol (g [dry weight] of cells)⁻¹. Data display the means ± 1 standard deviation from three measurements.