Characterizing a Purple Pigment Defect and Its Microbial Origin in Cheese Rinds

Abstract

Surface- ripened cheeses have a clear pattern of microbial succession which contributes to the overall quality of the product. These rinds typically contain the visible products of microbial activity including pigments, which contribute heavily to the aesthetics of the rind. Most of these pigments have not been matched to their microbial producer or producers. By reconstructing cheese rind microbial communities in the lab, I recreated an unexpected purple pigment originally observed in a production cheese farm. This purple rind defect is an interesting microbial pigment problem that has not yet been characterized. Two microbes of the same phylum create similar pigments, a mixture of indigo and indirubin, when cultured solo or together. The pigments were isolated and identified by thin layer chromatography. Other phylogenetically diverse microbial species were also able to produce purple pigments, suggesting this could be a common trait in cheese rind microbiomes. These investigations provide new insights into pigment production within limited microbial communities.