Quantitative and Qualitative Estimation of Bacteria Contaminating Human Hairs

Abstract

Human hairs have been known to be easily contaminated with microorganisms. This study was performed in order to measure what bacterial species and how much microorganisms contaminate human hairs in specific place. Virgin human hairs were left at 6 positions in inside corner and beside window in a laboratory for 7 days. The number of viable bacterial cells, which were determined by most probable number method, contaminating the human hairs was measured at a maximum of 10?/g hair and a minimum of 10³/g hair in inside corner and maximum of 10?/g hair and a minimum of 10³/g hair beside window. The bacterial cells-contaminating human hairs were observed via fluorescence light microscopy after 4',6-diamino-2-phenylindole (DAPI) staining. The bacterial community contaminating human hairs was analyzed via the thermal gradient gel electrophoresis (TGGE) technique, based on the diversity of the 16S-rDNA variable region. In total, approximately 20 bacterial species were detected from 12 groups of hair samples. In this study, general experimental methods-fluorescence staining, TGGE and MPN-were combined to develop new method for observation and estimation of bacteria contaminating human hairs.