I have recently experimented with different growth mediums for FUNGUS. I have discovered that whole grain Wheat Chex, as a substitute for rice powder, works nicely. The mycelium growth is constant and hearty. I can only assume that rice or corn Chex will work as well.
Also, in regards to injecting dextrose water into nearly expired cakes. Rather than using the traditional 10cc syringe, I have devised a simple drip method in which a two liter soda bottle is hung upside down and, a tube is run from the mouth of the bottle to the cake, which is attached by way of a hypodermic needle. A hole is punched in the bottom of the bottle just large enough to allow one drop of a 1:10 ratio of dextrose and water, respectively, to make its way to the cake every hour. By doing this the productive life of the cake is extended indefinitely. Modifications can be made to the mixture to adjust for moisture problems (i.e. a greater dextrose content, and a lower drip frequency to reduce moisture content of the cake. Or vice versa). An adjustable clamp can be applied to the tube to control the drip frequency. I believe that these methods hold much potential and can be greatly expanded upon.