Deep inside the Frasassi cave system in Italy and more than 1,600 feet below the Earth's surface, divers found filamentous ropes of microbes growing in the cold water, according to a team of Penn State researchers.
"Sulfur caves are a microbiology paradise. Many different types of organisms live in the caves and use the sulfur," says Jennifer L. Macalady, assistant professor of geosciences. "We are trying to map which organisms live where in the caves and how they correspond to the geochemical environment."
In this process, Macalady and her team discovered a previously unknown form of biofilm growing in the oxygen-deficient portion of the lake.
"The cave explorers had seen these strange biofilms," says Macalady. "So we asked them if they could get us a sample."
The Frasassi cave system is located north of Rome and south of Venice in the Marche region. These limestone caves are like New Mexico's Carlsbad Caverns and Lechuguilla Cave, but in those caves, sulfur entered the caves from oil and gas reserves, while in Italy, the sulfur source is a thick gypsum layer below. Having sulfur in the environment allows sulfur-using organisms to grow.
The researchers received about the weight of two paper clips of the strange rope to analyze. They reported the results of their DNA sequencing today (Dec. 19) at the American Geophysical Union Conference in San Francisco.
"We did not retrieve any sequences for known methane-producing organisms or known methane oxidizers," says Macalady.
The researchers did find that about half the organisms were bacteria and the other half belonged to another single-celled group of organisms called archaea. The researchers identified half the bacteria as sulfate reducers, bacteria that convert sulfates into sulfide to obtain energy. Of the archaea, more than half were associated with organisms usually found in deep sea sediments and referred to as marine benthic group D (MBG-D). Researchers do not kno
|Contact: A'ndrea Elyse Messer|