Barry Marshall and colleague Robin Warren have been awarded the Nobel prize for Medicine.
Barry Marshall is a member of the global faculty at GastroHep.com.
The research team discovered that peptic ulcer are usually caused by a bacterial infection.
The researchers will equally share the prize, which brings an award of approximately $1.3-million.
Sweden's Karolinska Institute will present the prize in December.
The researchers showed the bacterium H pylori plays a key role in the development of both gastric and duodenal ulcers, as well as a pivotal role in the development of gastric cancer.
Barry Marshall completed his undergraduate medical degree at the University of Western Australia in 1974, and an internship at Queen Elizabeth II Medical Centre.
Barry Marshall met Robin Warren during internal medicine fellowship training at Royal Perth Hospital in 1981.
Profesor Warren paved the way for the breakthrough when he discovered that small curved bacteria colonised the lower part of the stomach in about 50% of patients from which biopsies had been taken.
He also made the crucial observation that signs of inflammation were always present in the stomach lining close to where the bacteria were seen.
Barry Marshall became interested in the findings and together the researchers initiated a study of biopsies from 100 patients.
| Barry Marshall proved H. pylori caused gastric inflammation by deliberately infecting himself with the bacterium|
Together, the pair studied the presence of spiral bacteria in association with gastritis.
After several attempts, Dr Marshall succeeded in cultivating a hitherto unknown bacterial species - H pylori - from several of these biopsies.
Together the researchers found that the organism was present in almost all patients with gastric inflammation, duodenal ulcer or gastric ulcer.
Even though stomach ulcers could be healed by inhibiting gastric acid secretion, they frequently relapsed.
The research team noted that the peptic ulcers tended to recur because bacteria and chronic inflammation of the stomach remained.
Barry Marshall and showed patients could only be cured when H pylori was eradicated from the stomach.
Dr Marshall proved that H pylori caused gastic inflammation by deliberately infecting himself with the bacterium.
The work produced one of the most radical and important changes in the last 50 years in the perception of a medical condition.
The Nobel citation praises the doctors for their tenacity, and willingness to challenge prevailing dogmas.
"By using technologies generally available they made an irrefutable case that the bacterium H pylori is causing disease.
"By culturing the bacteria they made them amenable to scientific study."
Lord May of Oxford, President of the Royal Society, commented, "The work by Barry Marshall and Robin Warren produced one of the most radical and important changes in the last 50 years in the perception of a medical condition.”
"Their results led to the recognition that gastric disorders are infectious diseases, and overturned the previous view that they were physiological illnesses."
On becoming a researcher, Dr Marshall commented, “When I was in medical school I was given the impression that everything had already been discovered in medicine.”
“So I never thought that medical research would be interesting, but as I did my internship ... I realised there were a lot of people who had things wrong with them that you couldn't do anything about particularly."
In 1982, when H pylori was discovered by the researchers, stress and lifestyle were considered the major causes of stomach and intestinal ulcers.
It is now firmly established that the bacterium causes more than 90% of duodenal ulcers and up to 80% of gastric ulcers.
As a result of the researchers' work, these ulcers are often no longer a long-term, frequently disabling problem and can be cured with a short-term course of antibiotics taken with a gastric acid anti-secretory drug.