THE HUMBLE frog could hold the key to life saving medicines of the future, according to researchers.

Scientists in Glasgow claim the foam which tropical mud puddle frogs lay their eggs inside could be a rich source of undiscovered antibiotics.

The frothy bubbles, whipped up by the tiny creatures' back legs during mating, can protect their tadpoles for up to three days from deadly bacteria in the environment.

Following the award of a #170,000 research grant, scientists are now testing the foam to see if it will destroy germs harmful to humans.

Professor Malcolm Kennedy of Glasgow University's division of infection and immunity, said he became fascinated with the Physalaemus Pustulosus frogs during a field trip to Trinidad.

He noticed that despite being laid in muddy puddles and ditches full of bacteria, the eggs managed to survive. He teamed up with Professor Alan Cooper of the University's department of chemistry, to determine how the foam protected the eggs in such unhygienic conditions.

Professor Kennedy said: ''The foam nests float on the water in quite harsh conditions, as it lies in the tropical sun for two to three days under microbial attack.''

On research trips to Trinidad during the rainy season the scientists capture pairs of mating frogs in the middle of the night, and take them to the University of West Indies. ''We let them mate and produce the foam nests, which are about the size of an orange and contain about 200 tadpoles,'' said Prof Kennedy.

''Then we separate the protein from the eggs and bring it back here frozen. We have also brought frogs back with us. They are very common throughout Central and South America and are by no means endangered.''

After breaking down the foam's proteins, the team apply the substance to dishes containing germs and note the effect.

Professor Cooper said: ''You put the bacteria on a petri dish and add small smaples of the foam and look to see whether they are killed. So far we have tested it on ones available in the University such as E-coli.

''We have had some hints of success, but as yet we do not know what sort of bacteria the foam is aimed at. There are hundreds, if not thousands of pathogens, or disease causing agents. It is a question of trial and error. We have faith that the foam does contain antimicrobials, as otherwise the eggs would not survive.''

The project is backed by the Wellcome Trust, and is set to run for two years.