SHENZHEN, China (Reuters) — Some of the hundreds of bacteria found in the digestive systems of humans may be linked to specific diseases like cancer, diabetes and obesity, an international team of scientists said in a paper.

Researchers, led by Chinese scientist Wang Jun, said in the latest issue of Nature they found more than 1,000 different species of bacteria in the human gut.

They said they had sequenced, or analysed, the genes of each bacteria, creating the first genetic catalogue of the organisms found in the human digestive system.

Their research was based on analysis of stool samples from 124 people from Denmark and Spain.

Wang and his fellow researchers found several genes that may be linked to obesity and Crohn's disease, but he said more validation work was needed.

"Apart from helping you digest, these bacteria may also play a very important role in ... diseases like Crohn's disease, cancer, obesity," Wang, executive director of the Beijing Genomics Institute, said in an interview with Reuters.

"If you just tackle these bacteria, it is easier than treating the human body itself. If you find that a certain bug is responsible for a certain disease and you kill it, then you kill the disease," Wang said.

Crohn's disease is an inflammatory illness of the intestines which some believe may be caused by a variety of bacteria. Other possible causes include genetics and environmental factors.

Wang said creating the genetic catalogue of all the bacteria in the human gut was only a beginning.