Second, the human must have certain strains of bacteria living within the intestine.

He thought that a wild strain of bacteria had invaded the cell culture.

However, further research is needed on individual strains of beneficial bacteria for more refined recommendations.

These organisms have been shown to be new strains of previously discovered bacteria.

However, they are known to be present in at least eight strains of cultivated bacteria.

"We are constantly developing new strains of viruses and bacteria," they said.

But a powerful strain of bacteria may cause symptoms to appear much faster, within a few days.

These phages are used to identify different strains of bacteria within a single species.

In a control test, each strain of bacteria was simply propagated on its own.

But some strains of bacteria find them to be a tasty meal.