Finnish scientists say certain bacteria, shown to be beneficial for human health, are found in greater abundance in non-urban surroundings.The microbiota play an important role in the development and maintenance of the immune system, they add.The findings appear in the Proceedings of the National Academy of Sciences."There are microbes everywhere, including in the built environment, but the composition is different between natural environments and human-built areas," explained co-author Ilkka Hanski from the University of Helsinki."The microbiota in natural environments is more beneficial for us," .'Special function'The team collected samples from 118 teenagers in eastern Finland, and found that those living on farms or near forests had more diverse bacteria on their skin, and also displayed lower allergen sensitivity."They are important for us because they promote microbiota… that are important for the normal development and maintenance of the immune system," Dr Hanski observed.The study also allowed the team to identify one class of bacteria, known as gammaproteobacteria, which had a "special function"."It demonstrates that there are different functions between different microbes," he said.One type of gammaproteobacteria , called Acinetobacter, was singled out as being "strongly linked to the development of anti-inflammatory molecules"."Basically, our study showed that the more you had of this particular gammaproteobacteria on your skin then you had a immunological response which is known to suppress inflammatory responses ( to pollen, animals etc)."Dr Hanski said that there was a tendency for gammaproteobacteria to be more prevalent in vegetative environment, such as forests and agricultural land rather than built-up areas and water bodies.