Scientists discover some of Australia’s oldest prehistoric bacteria

Some of the oldest examples of prehistoric bacteria of its kind in Australia have been discovered by an international research team.

Deakin University palaeontologists Professor Guang Shi and Dr Elizabeth A. Weldon were part of an international team that found the 268 million year-old bacteria on the coastline near Wollongong.

The bacteria was revealed in a trace fossil—the markings or impressions produced by a creature—believed to have been made by an ancient marine animal.

The researchers believe the bacteria may hold valuable early clues to climate change.

Professor Shi said the team, which included scientists from China, accidentally came across the 268 million year-old fossilised bacteria while on the hunt for other fossils.

Professor Shi and Dr Weldon's collaborator, Professor Yi-Ming Gong from China University of Geosciences, collected some of the trace fossils and took them back to China where he cut and polished the rock and took small samples. Through stringent laboratory treatments and powerful Environmental Scanning Electron Microscope (ESEM) analysis he discovered the bacteria.

"The fossilised bacteria colony looks like a bunch of grapes at microscopic level inside the trace fossil,'' Professor Shi said.

Two different types of bacteria were found in different layers within the trace fossil in the rock. According to the researchers, they may provide valuable clues about how animals reacted to climate change.

"The alternating arrangement of the different layers of sediment containing different bacteria fossils could represent a response of the animal to warm and cold climate changes," Professor Shi said.

"We know the climate was oscillating at that time during a global climate transition from an icehouse to a greenhouse state, and the rhythmic climatic oscillations are indeed reflected in both sediment type and animal behaviour living in the ancient environment."

Professor Shi said the find was highly significant.

"We knew there were trace fossils at the site but we did not know what was inside them. We certainly did not expect to find grape-like fossilised bacteria colonies.

"This is the first report from Australia of this kind of fossilised bacteria of this age," he said.

The research team plans to return to the area for more fieldwork to determine the spread of the fossils.