Bacterial contamination on proteinaceous objets d'art such as parchment and mummies exposed to low relative humidity and low oxygen levels has been assessed using a polycarbonate NUCLEPORE filter and incident light (epifluorescence) microscopy. The technique described is a rapid and sensitive means for observing and evaluating bacterial populations including anaerobic organisms involved in the depolymerization of collagen. Using contaminated 17th-century parchment treated to microenvironmental control and modified atmospheres, a positive relationship has been found between fluorescence counts and plate colony counts.