(September 10, 2015) Tiny
microbes like the ones in Kabuno Bay may have created some of the world’s
largest ore deposits.
An isolated, iron-rich bay in the heart of East Africa is
offering scientists a rare glimpse back into Earth’s primitive marine
environment, and supports theories that tiny microbes created some of the
world’s largest ore deposits billions of years ago.
According to University of British Columbia research
published this week in Scientific Reports, 30 per cent of the microbes in the
Democratic Republic of the Congo’s Kabuno Bay grow by a type of photosynthesis
that oxidizes (rusts) iron rather than converting water into oxygen like plants
and algae.
“Kabuno Bay is a time machine back to the Earth’s early
history when iron-rich ocean chemistry prevailed,” said Marc Llirós of the
University of Namur, first author of the paper.
“The bay is giving us real-world insight into how ancient
varieties of photosynthesis may have supported Earth’s early life prior to the
evolution of the oxygen producing photosynthesis that supports life today,”
said UBC geomicrobiologist Sean Crowe, senior author of the study.
While iron-photosynthesizing bacteria were discovered in
1993, the new Scientific Reports study provides evidence that microorganisms
could have been directly involved in depositing the Earth’s oldest iron
formations.
Before 2.3 billion years ago, there was little oxygen in the
atmosphere but plenty of dissolved iron and many organisms like bacteria
derived energy by metabolizing the metal. Many researchers believe
iron-metabolizing microbes might have turned plentiful dissolved iron into
minerals, which then settled out of seawater and deposited along the ocean
floor.