Jekyll-and-Hyde factor makes marine bacteria cause 'coral bleaching'

Scientists are reporting the first identification of substances involved in the Jekyll-and-Hyde transformation that changes harmless marine bacteria into killers that cause "coral bleaching."

Researcher Dan Bearden and colleagues note that bleaching already has destroyed up to 30 percent of the world's coral reefs, and scientists are searching for ways to slow or stop the damage.

One known culprit is an ocean-dwelling bacterium, Vibrio coralliilyticus that chokes-off corals' energy supply and kills these shell-clad marine animals.

At lower temperatures, the bacteria are harmless to coral.

But at warmer temperatures (above 75 degrees Fahrenheit), the bacteria become virulent and can kill coral.

The new study reports identification of three chemicals - betaine, glutamate, and succinate - that V. coralliilyticus produces in warmer water and are involved in the transformation.

The discovery opens the door to understanding the biology involved in the complex interactions between corals and bacteria and unraveling the mystery of coral bleaching, the scientists indicated.