21 December 2006

Australian and US scientists have discovered a new group of organisms living in the pH equivalent of battery acid at a Californian mine.

University of Queensland scientist Rick Webb was working with scientists from the University of California when they uncovered the extraordinary life forms in acid mine drainage at the Richmond Mine on Iron Mountain in California.

He said the existence of these organisms was nothing short of remarkable considering the harsh environment they were found in.

“The samples for our project were collected from acid mine drainage which is at a pH of about 0.5 to 1,” he said.

“This is the equivalent of battery acid…so the fact that these organisms are living in this extreme environment is no mean feat in itself.”

Even more astounding is the minute size of the organisms.

“When observed with the electron microscope it became apparent to us that they are small - smaller than other organisms in the mine, and they appear to be similar in size to viruses,” he said.

“In fact they are so tiny that they are smaller than the minimum size expected on the basis of theoretical considerations for free-living cells.”

Had it not been for the use of a new method of studying the entire genomic information of the samples, this new group of organisms would have gone undiscovered.

Rick Webb and his colleagues did not isolate the microbes in the laboratory or use polymerase chain reaction (PCR), the methods typically employed to identify new microbes in the environment.

“Instead, we found them by directly isolating genomic DNA from the mine and sequencing the genomes of the organisms present,” he said.

“We have called these new organisms ARMAN - Archaeal Richmond Mine Acidophilic Nanoorganisms.”

Rick Webb, who was called into the project on the back of his expertise in the field of electron microscopy, said the discovery could open the possibilities for discovering new groups of organisms in different environments around the world.

“One of the important things about this study is that it illustrates that direct genomic sequencing of the environment is beginning to reveal entirely new groups of life overlooked using common methods,” he said.

In this case, the research could also have significant environmental implications, helping scientists to develop their understanding of the forces involved in acid mine drainage.

“Here, we discovered new groups of microorganisms, present everywhere we look in the mine, which significantly increases our understanding of life associated with this worldwide environmental problem known as acid mine drainage.”

The Iron Mountain site, which was mined for iron, silver, gold, copper, zinc and pyrite until it was closed in 1963, is well known for its problem with acid mine drainage.

“Historic mining activity has fractured the mountain, exposing its minerals to surface water, rain and oxygen.

“When pyrite is exposed to moisture and oxygen, sulfuric acid runs through the mountain and leaches out copper, cadmium, zinc and other heavy metals.

“These heavy metals, along with the acid run-off, drain into the local water system and eventually into the Sacramento River, causing a serious environmental problem.”

The research was part of a project to identify bacteria living within the acid mine drainage, [that are] involved in the reaction that releases heavy metals from the pyrite deposits.

Rick Webb said further study would be required for scientists to get a firm grip on the existence of the newly discovered organisms.

“We will need to isolate these ARMAN cells and grow them in the laboratory to be certain they are viable,” he said.

The research will be published in the December 22, 2006 edition of the prestigious international journal SCIENCE.

Rick Webb is a senior research officer at the University of Queensland’s Centre for Microscopy and Microanalysis and the School of Molecular and Microbial Sciences.

Media: For further information contact Lucy Manderson at UQ Communications (07 3365 2339 or 0404 388 584) or Rick Webb (07 3346 3959).

For high resolution images contact Diana Lilley (07 3365 2753).