From Delhi to Canberra and Oxford: Tanuka's journey studying deadly bacteria

Publication date
Thursday, 9 Jun 2022
A young woman in a shirt and jeans sits on a lawn at ANU, smiling at the camera.
Tanuka Sen. (Photo: Kirat Alreja/ANU.)

Tanuka Sen almost didn’t make it to Australia for her PhD studies. After completing her undergraduate studies in her home country of India, she applied to several universities in Europe. But there was a single Australian university on her list: ANU.

She already had a few offers from European universities, but then an ANU professor at the Research School of Biology got in touch with her, suggesting she apply for a scholarship.

“The process went so smoothly: I got this scholarship and decided to leave behind the offers from Europe and come to Australia,” says Tanuka.

Despite arriving in Australia just in time for severe bushfires, a hailstorm and a global pandemic, she says that coming to ANU was “the best option” for her: “I’m really happy with how it has turned out!”

Now that she’s finished her PhD, she gets to experience the best of both parts of the world after accepting an offer to continue her postdoctoral studies at the University of Oxford in the UK.

Across all of these countries, she’s been on a mission to discover more about Shigella, a group of bacteria that cause devastating diseases, primarily, bacillary dysentery, which is an “extreme form of diarrhoea”.

This diarrhoea is “not what you’d normally get after eating something bad – it can lead to blood in the stools and other severe complications, such as chronic arthritis,” Tanuka clarifies.

Tanuka researched a species of Shigella that is “very prominent in underdeveloped and developing countries where hygiene standards are lower”. According to the World Health Organization, bacillary dysentery causes more than a million deaths worldwide per year, often affecting children under five years old.

Researchers around the world have been working towards a vaccine for decades. However, with four different species of Shigella and multiple evolving strains, finding an effective vaccine is “a real struggle”.

One approach that could work is to find a protein that is common across all strains. But first, researchers need to know which all proteins exist and what they do.

“In all bacteria, and even humans as well, there are proteins called ‘hypothetical proteins’ that are abundantly present but we don’t know what they do in us, or in the bacteria,” says Tanuka.

“For example, in the bacterial strain I worked on, out of the 4,000 protein encoding genes, 720 of those were annotated as hypothetical proteins as their functions are not known. My project was based on functional genomics, which is trying to understand what those hypothetical proteins actually do in the bacteria and if they play a role in their growth, survival or virulence.”

Tanuka used computational methods to help predict which proteins were most likely to have important functional roles in the bacteria.

“Once you have that list, you need to do experimental work to prove that the computer’s prediction was right,” she says. “So out of the 720 proteins that I started with, I worked with around 25.”

“If I did experimental work for all 720 of those proteins, that’s about 10 PhDs of work!”

Ultimately her work will help contribute a piece of the puzzle towards developing an effective vaccine or new antibiotic drugs.

“It takes so much time to know what the functions of these hypothetical proteins are,” Tanuka says. “That’s partly why it’s so hard to find a good vaccine.”

“A vaccine would help us decrease our reliance on antimicrobials and antibiotics – and we know that antibiotic and multi-drug resistant bacteria are a bigger problem than anything else.”

Tanuka hopes to continue working as a researcher for many years to come, either as an academic or in industrial research working towards new preventative treatments.

“My undergraduate teachers told us in our first microbiology lecture to remember that all microorganisms are smarter than humans: you do something to fight them, and they’ll adapt to it, and fire back at you,” Tanuka says.

Soon, perhaps, humans will be much closer to outsmarting Shigella and saving millions of lives.

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