NOVELTY - Continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen and carbon dioxide in an aqueous menstruum containing microorganisms into alcohol comprises (a) continuously introducing the substrate in the form of gas bubbles at gas inlets of a bioreactor assembly, (b) maintaining contact between the gas bubbles and the menstruum, (c) continuously withdrawing substrate depleted gas phase from the bioreactor assembly at the gas outlet, and (d) continuously or intermittently withdrawing a portion of the menstruum from the bioreactor assembly.    USE - The continuous process is useful for the anaerobic bioconversion of a gas substrate into alcohol (claimed) including ethanol, propanol and butanol.    ADVANTAGE - The continuous process is capable of anaerobic bioconversion of the gas substrate with high yield and conversion efficiency and reduced operating costs and energy consumption.    DETAILED DESCRIPTION - Continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, hydrogen and carbon dioxide in an aqueous menstruum containing microorganisms into alcohol comprises: either (a) continuously introducing the substrate in the form of gas bubbles at one or more gas inlets of a bioreactor assembly having at least one bioreactor for containing the menstruum, where the bioreactor has at least one gas inlet and at least one gas outlet, at least one bioreactor in the bioreactor assembly has a substantially uniform aqueous menstruum and a substantially non-uniform substrate concentration between the gas inlet and the gas outlet, and the cumulative substrate introduced into the bioreactor assembly through the gas inlets has a ratio of electrons to carbon atoms of 5.2:1-6.8:1, (b) maintaining contact between the gas bubbles and the menstruum to provide an alcohol-containing menstruum and a substrate depleted gas phase at a gas outlet of the bioreactor assembly, where duration of contact is sufficient to convert at least 80% of the hydrogen in the gas substrate to alcohol, (c) continuously withdrawing substrate depleted gas phase from the bioreactor assembly at the gas outlet, where the substrate depleted gas phase being withdrawn from the bioreactor assembly has a partial pressure of carbon dioxide of 2.5-25 kPa, and (d) continuously or intermittently withdrawing a portion of the menstruum from the bioreactor assembly for recovery of the alcohol, where the withdrawal is sufficient to maintain the alcohol in the menstruum below a concentration that unduly adversely affects the microorganisms; or continuously reforming a hydrocarbonaceous feedstock by autothermal reforming using air as the source of oxygen for the autothermal reforming, where the autothermal reforming is operated to provide a syngas having an electron to carbon atom ratio of 5.5:1-6.0:1 and a nitrogen concentration of 25-35 mole%, and the steps (b)-(d) as above per se. An INDEPENDENT CLAIM is included for a process-I for controlling the operation of the bioreactor assembly for the anaerobic bioconversion of the gas substrate comprising adjusting the ratio of electrons to carbon atoms gas bubbles at the gas inlet portion to be 5.2:1-6.8:1, and adjusting the carbon dioxide concentration in the gas substrate to provide the partial pressure of carbon dioxide in the substrate depleted gas phase at the gas outlet portion to be 2.5-25 kPa.