The late Frank Zappa is back for an encore, this time as a formerly pimple-causing bacterium that has apparently moved from human skin to the bark of grape vines. Italian researchers named the new bacterium P. acnes Zappae after the genre-bending and iconoclastic Zappa - whose surname in Italy also means "hoe" - in a nod to the agrarian roots of the wine-related institute where the discovery was made. "This is the first time it's been found that a micro-organism can switch from a human to a plant," said microbiologist and ardent Zappa fan Andrea Campisano of the Edmund Mach Foundation, lead author of the study published in the latest issue of the journal Molecular Biology and Evolution . Campisano said he played Zappa's music regularly and kept a quote from the rock musician displayed on his computer screen in the laboratory: "If you end up with a boring miserable life because you listened to your mom, your dad, your teacher, your priest, or some guy on television, then you deserve it." So when the researchers detected the DNA of a bacterium in grape vine cells that looked suspiciously like that of a common human acne bug, they didn't toss it out as a contaminated sample, according to co-author Omar Rota-Stabelli, an evolutionary microbiologist at the foundation. They followed their muse, who once said he made a living by drawing dots on paper and connecting them. Rota-Stabelli used a "molecular clock" analysis, based on rates of DNA mutation, to estimate when the bacterium might have made its leap from finger to vine. "It turns out that the most probable date is about 7,000 years ago, which is when we estimate that we started cultivating grape vines," said Campisano. "Probably as soon as humans started to touch this plant, this bug that used to live on human skin found a very hospitable environment inside the cells of the grape vine." Comfortably ensconced in bark tissue and pith, the bacterium does not appear to harm the grape vines. Researchers believe it simply changed its appetite from human fatty acids to those of plant cells. "It has extensively restructured its genome and DNA and it's now unable to go back to its earlier, human-associated form," said Campisano. And that's a state of being that Frank Zappa probably would appreciate.