Abstract: This invention is a method to rupture microbial cells in order to recover intracellular material in the cells comprising:a) treating the cells with carbon dioxide under pressure sufficient to enter the cells for time sufficient to allow enough carbon dioxide into the cells to effect later rupture, thenb) suddenly releasing the applied fluid pressure on the cells so that the outer wall or membrane of the cells is ruptured by the expansion of carbon dioxide within the cell. Preferably the remaining intracellular material of the cells is separated and recovered. Also the treatment can be in conjunction with lytic enzyme to increase rupture rates. Preferably the enzyme remains active and protein in the cells retains its native state in the ruptured cell suspension. The preferred time for treating is from between about one hour and about fifteen hours. It is also preferred to treat initially at a pressure of from above about 500 psi gage to about 5000 psi and a temperature of about 10.degree. to about 85.degree.