Scientists have found more than 250 species of bacteria dwelling on the human forearm, around the number of animal species in a zoo, which prompts lead researcher Martin Blaser to conclude it's a 'zoo' of bacteria out there on the human body.
Stating that he wanted to explore the skin as a source of bacteria, as it was practically uncharted area, unlike the intestinal tract, vagina, mouth etc., Blaser says he was astounded by results of his work, which he describes as 'deep.'
Investigators discovered 182 bacterial species in a swab taken from the forearms of six men and women. They cultivated the microbes by isolating genetic material and analyzing sequences of DNA, using a powerful forensic technique.
Four of the volunteers were followed up several months later; the researchers detected an additional 65 microbes, bringing the total closer to almost 250.
In findings reported in the journal Proceedings of the National Academy of Sciences, Blaser and colleagues were amazed to see around 8 different species of bacteria which were not known to man, before, though Blaser says this is not uncommon in detailed bacterial sampling of human organs.
The scientists also found the variety of bacteria on any one individual changed over the several months in which the swabs were taken. The predominant species did not change much but the transient bacteria did vary over time.
"What that suggests is that there is a scaffold of bacteria present in everybody's skin. Some stay and others come and go," Professor Blaser said.
The study was part of a larger effort to examine the entire range of human microbial ecology.
It is estimated that the body's microbial cells outnumber human cells by 10 to one.
"Most of the bacteria that are present in the human body are beneficial. They are helping us. So, we want to understand these beneficial organisms much better so that we may be able to harness them some of the molecules that communicate with human cells so that we have better medicines," says Blaser.
Blaser envisions this work as being helpful in the study of microbes of the skin that may help in the treatment of psoriasis and eczema.