Extreme Degradation of Human Hair by Keratinophilic and Keratinolytic Fungi

Head hairs from a 19-year-old female murder victim, who had been buried for 36 years, were examined by scanning electron microscopy (SEM) and transmitted light microscopy. The hairs exhibited a range of biodeterioration artifacts. In some areas on the hairs, the cuticular scales were intact; in others, scales had become loosened; and in yet other areas, scales had been completely lost, exposing the underlying cortical cells. Three different types of fungal tunnels were observed: thin, thread-like tunnels; conical tunnels that narrowed as they penetrated the shaft of the hair; and conical tunnels that increased in diameter as they penetrated the hairs. These fungal tunnels are consistent with the growth of both keratinophilic and keratinolytic fungi. In some hairs, fungal hyphae had penetrated to the center of the hair and consumed the central medullary cells. In extreme cases, the hairs were reduced to hollow tubes resembling soda straws. A fungal penetrating organ was observed in situ, protruding from the shaft of the hair. The lack of cellular disruption surrounding this penetrating organ indicated that it had penetrated the hair by digesting the keratin of the cuticular and cortical cells. The extent of microbial attack on the hairs suggests that conditions (temperature, humidity and presence of a growth substrate) in the coffin were initially extremely favorable to fungal growth. The survival of substantial numbers of hair is most likely due to a fall in humidity due to loss of moisture from the coffin.