The researchers, led by the University of California-Santa Cruz, also found at least 94 other bacterial species possess the DNA code for light detection.

"These bacteria have been very well studied for years and no one knew they could sense light," said the study's lead author Trevor Swartz. "Now it seems like it's a common thing, rather than being an anomaly."

"We have bumped into an entirely new family of light receptors in nature," said study co-author Professor Roberto Bogomolni, who said it's still not clear how the regulation of virulence by light benefits the pathogen.

Researchers also included University of California-Santa Cruz graduate student Marcus Frederickson, Winslow Briggs and Tong-Seung Tseng of the Carnegie Institution of Washington; Gaston Paris and Fernando Goldbaum of the Leloir Institute Foundation in Argentina, Diego Comerci and Rodolfo Ugalde of Argentina's National University, Gireesh Rajashekara and Gary Splitter of the University of Wisconsin; and Jung-Gun Kim and Mary Beth Mudgett of Stanford University.

The study appears in the journal Science.