TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The vessel is a stirred tank bioreactor, two-stage bioreactor, and/or bubble column bioreactor.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The step (c) takes place via either sterile feed or batch addition prior to sterilization. The process further comprises: diluting the fermentation liquid gradually after inoculation to a final concentration of 20-160 mg/l through addition of a feed medium that is depleted in or that contains no surface tension active compound; and passing at least a portion of the inoculated fermentation liquid from the vessel receiving the surface tension active compound to a second vessel in a seed train, where the second vessel has a larger volume than the vessel receiving the surface tension active compound. The process-I further comprises maintaining a proportional-integral-derivative (PID) feedback loop based on carbon oxide and hydrogen gas uptake rates, either manually or via PID controller, to add feed medium containing a concentration of surface tension active compound to restrict carbon oxide solubility to a desired level. Preferred Components: The surface tension active compound meets the criteria of: lack of toxicity or negative effects on acetate, ethanol, or cell growth at concentrations up to 1000 mg/l; exhibits a dynamic surface tension after 3000 milliseconds of incubation of less than 40 dyne/cm for broth phase samples containing a minimum cell concentration of 6.3 g dry cell weight per liter; does not adversely impact downstream processes including recycle processes, ethanol recovery, and final product quality; and is not metabolized into active nutrients that could support foreign growth of microorganisms or into any environmental toxin. The surface tension active compound comprises: polyols and glycols; and Cognis FBA 975US, Cognis 36K, and Cognis 153K. The fermentation liquid contains a microorganism comprising Clostridium coskatii, Clostridium autoethanogenum, Clostridium carboxidivorans, Clostridium ljungdahlii, Butyribacterium methylotrophicum, or Clostridium ragsdalei.