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Microbial Ecology of Human Skin

[View an entertaining video clip shot in the Blaser Lab: "Life On Our Skin,"
produced for NPR's Science Friday by Flora Lichtman
]

 


The microbial ecology of human skin is complex, but little is known about its species composition.  We examined the diversity of the skin biota from the volar left and right forearms in six healthy subjects using broad-range 16S rDNA PCR-based sequencing of randomly selected clones.

For the initial 1,221 clones analyzed, 182 SLOTUs (species-level operational taxonomic units) belonging to 8 phyla were identified, estimated as 74.0% (95% CI: 64.8%~77.9%) of the SLOTUs in this ecosystem; 48.0±12.2 SLOTU were found in each subject. Three phyla, Actinobacteria, Firmicutes, and Proteobacteria, accounted for 94.6% of the clones. Most (85.3%) of the bacterial sequences corresponded to known and cultivated species, but 98 (8.0%) clones, comprising 30 phylotypes, had <97% similarity to prior database sequences. Only 6 (6.6%) of the 91 genera and 4 (2.2%) of the 182 SLOTUs, respectively, were found in all six subjects.

Analysis of 817 clones obtained 8 to 10 months later from four subjects, showed new phyla (2), genera (28), and SLOTU (65). Only four (3.4%) of the 119 genera (Propionibacteria, Corynebacteria, Staphylococcus, and Streptococcus) were observed in each subject tested twice, but these represented 54.4% of all clones. These results show that the bacterial biota in normal skin is highly diverse, with few well-conserved and well-represented genera, but otherwise low-level interpersonal consensus.

Zhan Gao, MD

Zhan Gao, MD


Table 1.
Distribution of 2,038 16S rDNA clones from  forearm skin of six healthy subjects:

Subject

                                        Number of clones studied

First sampling

Second sampling

 

Designation

Age (years)

Sex

Left forearm

Right forearm

Total

 

Left forearm

Right forearm

Total

Number of months apart

A

41

F

105

103

208

 

100

103

203

10

B

21

F

103

101

204

 

NA*

NA*

NA*

NA*

C

31

F

103

 99

202

 

101

105

206

8

D

53

M

101

103

204

 

NA*

NA*

NA*

NA*

E

54

M

100

103

203

 

103

 99

202

10

F

29

M

102

 98

200

 

102

104

206

8

Total

 

 

614

607

1,221

 

406

411

817


 

Table 2.
Subject samples with links to 2,038 DNA sequences from human forearm skin:
The study was funded by the National Institutes of Health (NIH), by a Senior Scholar Award from the Ellison Medical Foundation, and by the Diane Belfer Program in Human Microbial Ecology in Health. The authors of the study are Zhan Gao, M.D., Chi-hong Tseng, Ph.D., Zhiheng Pei, M.D., Ph.D., and Martin J. Blaser, M.D.

 

 

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