Bacteria's invisible predators in the Merri

Like all of Australia’s waterways, the Merri is home to a diverse set of microbes: bacteria, viruses, fungi and other single-celled organisms. We’ve been really keen to study an armour-coated subset of viruses in the creek: the bacteriophages (for short: phages).

Bacteriophages (red) are the natural predators of the much larger bacteria (blue). Photograph from iStock

In nature – including in the Merri – phage act as bacteria’s natural predators, helping to keep bacterial populations in check. However, these phages can also be harnessed to treat bacterial populations that cause food spoilage, or infections, in people, animals and plants.

“Melbourne's waterways, like Merri Creek, are thriving ecosystems at the microscopic scale.
Even the most mundane site can support a diverse heritage of microbes in its waters.” Alex Hall.

In 2019, we collected Creek water and, through an isolation and analysis process, identified two new phages. We worked with Wurundjeri Elder, Aunty Gail Smith, to name the phages in Woi-wurrung language. The Centre to Impact AMR scientists were able to determine the characteristics of the bacteriophage, which assisted in the appropriate naming of the phage. Both phage had unique physical attributes and their specific hunting style, so the phage were named, based on how they hunt.

Merri-meeri-uth nyilam marra-natj (MMNM)

This phage makes surprise encounters with its prey (bacteria). It uses its short bulbous legs to make contact with the bacteria. These legs help it bury into the bacteria's surface and trigger the phage to contract like a spring. In this crouched position, it kills the bacteria.

Drawing by Dr Eleanor Jameson

Merri-merri baany-a bundha-natj (MMBB)

The second phage was named Merri-merri baany-a bundha-natj (MMBB), which translates as “Merri water biter.” This phage moves like a snake to strike its prey (bacteria). It chews into the bacteria, then replicates inside the bacteria and releases its progeny into the creek water.

Drawing by Dr Eleanor Jameson

We published our first scientific article on this project in 2021, forever embedding Woi-wurrung language in the scientific literature. There are several more we are currently working on. These two phages served as test cases for the development of new software for recognising and characterising new and previously unseen phages from any of Australia’s waterways.

In our current work, we are also trying to understand why some of the bacteria in waterways, like the Merri, are evolving to become antimicrobial resistant (i.e. superbugs). With the increasing industrialization and population density of the space near creeks, the spread of contaminants, including soaps and other cleaning products, into our water has increased. We hope that by closely monitoring these waterways, leaning on both traditional knowledge and modern science, we can create a more sustainable future for our special places like Merri Creek.

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Authors
Kayla Cartledge (Gurindji) is the Aboriginal Communities Engagement Lead at the Centre to Impact AMR, Monash University

Alex Hall is a PhD student in the Department of Microbiology at Monash University

Trevor Lithgow is a Professor in the Biomedicine Discovery Institute at Monash University

Artwork
Dr Eleanor Jameson, Monash Warwick Alliance

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Source:  Friends of Merri Creek's Newsletter