A process for capturing or concentrating microorganisms for detection or assay comprises (a) providing a concentration device comprising a sintered porous polymer matrix comprising at least one concentration agent that comprises an amorphous metal silicate and that has a surface composition having a metal atom to silicon atom ratio of less than or equal to 0.5, as determined by X-ray photoelectron spectroscopy (XPS); (b) providing a sample comprising at least one microorganism strain; and (c) contacting the concentration device with the sample such that at least a portion of the at least one microorganism strain is bound to or captured by the concentration device.