FIGURE 1.

Scheme of the A-stat (accelerostat) and De-stat (decelerostat) experimental set-up. The pooled fecal inoculum was added into 300 ml growth medium at time 0 h followed by batch phase (ca 15 h) until mid- exponential growth phase. Then continuous mode was started and after the stabilization of the fecal culture at D = 0.2 1/h (De-stat) or D = 0.05 1/h (A-stat, 6-7 residential times in total), the dilution rate was gradually decreased down to 0.05 1/h or increased up to 0.2 1/h (deceleration or acceleration rate 0.05 1/h per day), respectively, followed by re-stabilization for approximately 2 residential times. The same procedure was applied for two substrate combinations (birch xylan + mucin and, apple pectin + mucin). D_set indicates the controlled change of the dynamics of the pre-set dilution rate.