The researchers from King's College London research, Environmental Microbiology department, found that the compounds behind bad breath are produced when sulphur-containing amino acids break down in the mouth.
The odour-eating methylotrophic bacteria were isolated from the tongue, tooth plaques and gum edges of volunteers; it not been previously recognised that these bugs were a normal part of the microbial environment inside the mouth.
The King's college team found no difference between strains of bacteria found in the mouths of healthy volunteers and those suffering from periodontitis, a form of gum disease often associated with bad breath.
The researchers do however suspect that people who suffer from bad breath may have lower levels of the bacteria.
In previous work the King's team has shown that methylotrophic bacteria are found on the feet, where sulphur derivatives can also cause odours.
Lead researcher Dr Ann Wood has said that it might be possible to combat bad breath by modifying mouthwashes and toothpastes to enhance the activity of methylotrophic bacteria.
Dr Wood says that the levels of mouth bacteria varied depending on a number of factors, including gum and liver disease, smoking and diet.
They found that if concentrations of the smelly compounds were high, as in bad breath, the number of methylotrophs could also be expected to rise, but as these compounds are toxic this would potentially limit the bacterial activity.
An accumulation of material between teeth, coating the tongue and plaque deposition, will obviously occur if oral hygiene is poor, and this apparently is likely to raise the output of the relevant compounds.
Dr Phil Stemmer, of the Fresh Breath Centre in London, says he finds the theory promising.
However, he feels it is not just a case of increasing levels of potentially beneficial bacteria, they would have to replace other types of bacteria in the mouth that caused bad breath by breaking down amino acids.
"There's no reason to believe that this is the only compound in broccoli that has an anti-cancer effect," said Steven Clinton, a study co-author and an associate professor of hematology and oncology at Ohio State. "There are at least a dozen interesting compounds in the vegetable.
"We're now studying more of those compounds to determine if they work together or independently, and what kind of effects they have on cancer cells," he added.
Broccoli isn't the only cruciferous veggie with health benefits, the researchers say. The plant's kin, which include cabbage, cauliflower, Brussels sprouts and kale, may all contain similar disease-fighting phytochemicals.
It's too early to suggest just how much broccoli or other cruciferous vegetables should be eaten to stave off or slow down the progression of bladder cancer. Still, they are an important part of the diet.
"Cruciferous veggies have an effect on other types of cancer, too," Schwartz said. "We already know that they contain compounds that help detoxify carcinogens. We're thinking more along the lines of progression and proliferation, such as once cancer starts, is there a way to slow it down?"
He and Clinton conducted the study with Ohio State colleagues Robin Rosselot, a graduate student in food science and technology and Qingguo Tian, a research associate also in food science and technology.
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