Human skin comprises a large number of distinguishable ecological niches. To describe fully the human skin microbiome, it will be necessary to identify the bacteria in each niche and to distinguish the commensal bacteria from the temporary residents. To contribute to the description of the human skin microbiome and employing a gene-based technology, we have identified the bacteria in two niches: the front and back of the base of the neck and over the course of one year. There were 50 volunteers and a total of 232 neck skin swabs. Roche 454 Tag pyrosequencing was employed to sequence a short hypervariable sequence region (V6) of the 16S ribosomal RNA gene. To identify the bacteria corresponding to the front and back of the neck for each volunteer, the Classifier software in the Pyrosequencing section of the Ribosomal Database Project was employed. The bacteria on virtually all 232 neck skin swabs were classified into bacterial Class. The skin microbiome of these two niches was composed principally of a mixture of five Classes of bacteria: Actinobacteria, Alphaproteobacteria, Bacilli, Betaproteobacteria and Gammaproteobacteria. The fraction of each Class could change over time. We could not distinguish the skin microbiome from the front of the base of the neck from the back of the base of the neck. At these two positions, we could not distinguish the male from the female skin microbiome. The principal variable was the time point. We concluded that the skin microbiome at the front and back of the base of the neck was composed principally of a mixture of five Classes of bacteria. The proportion of each Class could change over time.
