Development of Biocide-Tolerant Microorganisms in Additives and Coating, 2001 Coating Conference Proceedings

Margaret M. Palcic, Graziella Teodorescu--Biocides are routinely added to additives and coating formulations in order to minimize the proliferation of microorganisms. If left uncontrolled, microorganisms and the by-products of their growth can result in the deterioration of additives and decreased coating and product quality. Occasionally, biocide programs in coating systems can become ineffective due to the development of populations of microorganisms that are tolerant to the control chemistries in use. Microorganisms can tolerate the effects of biocides through either intrinsic resistance or acquired resistance. Intrinsic or "natural" resistance occurs when the microorganisms avoid the effects of a biocide through a physical barrier, such as a capsule, or by the secretion of enzymes that detoxify the chemistry. Acquired resistance results from an alteration in the microorganism that decreases its sensitivity to a biocide. It is very important in maintaining microbiological control in a coating kitchen that the additives and coating be monitored for the development of biocide tolerance. If tolerance develops, an alternative biocide treatment plan must be available for regaining control of the microbiology of the additive. Finally, an understanding of the conditions that contribute to the development of tolerance can assist in minimizing a re-occurrence of the event.