NOVELTY - A process (P1) of converting feed gas using bioreactor containing microorganisms to produce liquid product and delivers the product to liquid phase on substrate opposite the gas phase involves: (a) passing the feed gas to substrate that retains biolayer (18) of microorganisms (14); (b) passing liquid phase over liquid contacting side of the substrate comprising hydration layer (20); (c) maintaining pressure on the gas contacting side (10) to transport the feed gas and liquid products to the liquid contacting side; and (d) periodically subjecting the biolayer to laving cycle.    USE - For converting feed gas to liquid product such as ethanol, n-butanol, hexanol, acetic acid, and butyric acid (claimed), which are used in biofuels such as liquid motor fuels.    ADVANTAGE - The process of converting feed gas to liquid product such as ethanol, obtains enhanced productivity through the regular cycling of liquid across a substrate that supports a biolayer of microorganisms while separating the gas and liquid phases. The process enhances the diffusion of the liquid products and the hydration of the microorganisms across the membrane by cyclically pulsing nutrient containing liquid toward the microorganisms and then allowing the liquid to permeate back toward the liquid contact surface of the membrane. This laving action of periodically shifting the liquid gradient through the membrane moves liquid to and from the biolayer for improved nourishing of the microorganisms and allows maintenance of desired product concentrations.    DETAILED DESCRIPTION - A process (P1) of converting a feed gas using a bioreactor containing microorganisms to produce a liquid product where a liquid permeable substrate partitions the microorganisms from liquid phase, retains the microorganisms in direct contact with the gas phase to produce the liquid product and delivers the liquid product to a liquid phase on the side of the substrate opposite the gas phase, involves: (a) passing the feed gas to a substrate having a gas contacting side in contact with the feed gas that retains a biolayer (18) of microorganisms (14); (b) passing a liquid phase over a liquid contacting side of the substrate comprising a hydration layer (20) that controls the flow of product containing liquid from biolayer; (c) maintaining pressure on the gas contacting side (10) to establish a differential pressure between the gas contacting side and the liquid contacting side to transport the feed gas and the liquid products in co-directional flow from the gas contacting side to the liquid contacting side for a limited period; and (d) periodically subjecting the bio-layer to a laving cycle by reducing the first differential pressure such that liquid from the liquid contacting side laves into the biolayer.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic drawing showing a cross section of an asymmetric membrane with gas stream in contact with a biolayer that retains microorganisms and a hydration layer in the form of a skin in contact with liquid.    Gas contacting side (10)    Asymmetric membrane (12)    Microorganisms (14)    Biopores (16)    Biolayer (18)    Hydration layer as skin (20)