The present invention is a bioreactor or fermenter formed of a container having two or more walled. One or more inlets and one or more outlets are formed in one or more of the walls of the container. At least one of the one or more inlets is formed in the bottom wall of the container and used for the introduction of one or more gases. A gas distribution device is formed within the body of the container adjacent the bottom gas inlet and a hydrophobic filter is mounted to the bottom wall gas inlet, upstream of the gas inlet. The distribution device is formed such as by bonding the two facing wall surfaces of the container together at discrete and spaced apart locations to form a series of gas ports into the remainder of the container. The hydrophobic filter acts to purify the gas entering the container so as to prevent the introduction of contaminants such as microbes into the container. It also acts as a valve, preventing liquid in the bag from passing through its hydrophobic structure thus preventing any back flow when positive pressure from the gas supply is not being imposed upon the bag.