Experts have explored the remarkable diversity of microorganisms that play a critical role in maintaining the health of the Brisbane River. 

A research team has conducted an extensive 12-month survey of the river, employing cutting-edge DNA sequencing techniques to identify nearly 2,500 distinct microbial genomes.

Their research, which represents the largest microbial genome database ever compiled for a subtropical estuary, revealed that over 80 per cent of these microorganisms are new to science. 

The team collected samples from three locations along the Brisbane River: Indooroopilly, Eagle Farm, and Shorncliffe in Moreton Bay. 

The findings provide a comprehensive snapshot of the river's microbial ecosystem, highlighting its complexity and the crucial roles these tiny organisms play.

“Microbes are a handy indicator of the health of our waterways,” said study lead, PhD candidate Apoorva Prabhu.

“They’re efficient nutrient recyclers, processing carbon, nitrogen, phosphorus, and sulphur. Unfortunately, we found a high number of microbes that feed on nutrients like nitrates or phosphorus, indicating significant pollution from human activity such as agricultural runoff.”

One of the significant discoveries was a novel bacterium named Hypereutrophica brisbanensis, which serves as a key indicator of elevated nutrient levels in the water. “Whenever we encountered this bacterium, nutrient levels in the river were through the roof, and sadly, the reality is while these microbes remain well-fed, the river is suffering,” Prabhu said.

The study used advanced metagenomics, a method designed to study entire communities of microorganisms, along with machine learning techniques to identify the new species. This approach allowed the team to uncover the previously hidden diversity within the lower Brisbane River.

“Remarkably, more than 80 per cent of the microorganisms we found were entirely new to science, highlighting a vast and previously unexplored diversity,” said Prabhu. 

“This knowledge is vital for developing effective environmental monitoring and management strategies, as it specifically tells us what the most pressing issues are, pollution-wise, facing our waterways.”

“The integration of metagenomics and machine learning presents a robust framework for exploring microbial communities and their ecological functions,” said researcher Honorary Associate Professor Chris Rinke. 

“Future research can build on these findings to further explain the complex interactions within microbial ecosystems and their responses to environmental changes. Our next aim is to focus on the impact of floods on microbial communities.”

The research, published in ISME Communications, sets a new benchmark for microbial ecology research in estuarine environments, particularly in subtropical and tropical regions like Brisbane.