Kiwi scientists decode antibiotic-resistant bacteria

Andrea Graves

New Zealand Listener·

2 Feb, 2026 05:04 PM4 mins to read

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Adele Williamson: Found a piece of the puzzle on marine bacterium in the Arctic. Photo / Supplied

Sexually transmitted diseases are awful, particularly when you’re stuck with them. Gonorrhoea, for example, is now resistant to almost all classes of antibiotics in some countries. With global air travel that could eventually happen here too, because antibiotic-resistant versions spread rampantly. New Zealand has about 7500 gonorrhoea infections a year.

Concern about antibiotic resistance in general is growing, and four research projects on the topic won funding in the recent round of Marsden Fund grants. One, based at the University of Waikato, explores a previously unknown ploy that the gonorrhoea-causing bacterium seems to use to grab antibiotic-resistance genes from its surroundings and draw them into itself.

Chief investigator Adele Williamson describes how antibiotic resistance arises. “Somebody takes an antibiotic that kills off all the bacteria that don’t have that resistance gene and you’re left with the few bacteria that do. They then have a massive advantage over all their mates who weren’t resistant. They’re going to out-compete them. Now the antibiotic is no longer effective.”

But how do they acquire that gene? A few undergo a genetic mutation in whatever target the antibiotic works against, says Williamson. But some simply incorporate related bacteria’s DNA into their own.

Bacteria can get genes from other bacteria directly or from DNA in the environment. That could be anywhere that’s warm, moist and teaming with microbes, such as an infected body part or a wastewater treatment plant.

DNA tends to break up in the environment, limiting its usefulness. Williamson and her team, including infectious disease expert Joanna Hicks, biochemist Jolyn Pan and international scientists, think they’ve found a novel way some bacteria overcome that. It seems they make an enzyme called ligase E and expel it outside their cell membranes. There it homes in on broken DNA and repairs it so it again codes for antibiotic resistance. The bacteria then pull the repaired DNA strand inside themselves, perhaps with ligase E protecting it as it crosses the cell membrane, and incorporate it into their own genome.

There’s persuasive evidence for this hypothesis. For example, deleting the bacteria’s ligase E gene means it doesn’t become antibiotic resistant as easily. But there’s still proof-of-concept work to do, which the Marsden grant will fund.

The research is the latest step in Williamson’s exploration of the ligase E gene, which she came across by chance deep in the Arctic when working at a Norwegian university. There she found ligase E in marine bacteria. And she couldn’t let go of a certain enigma. “We were scratching our heads. That’s weird. It’s got a signal on it saying ‘send me outside the cell’. Why would a bacteria make a protein that should join pieces of DNA and then spit it outside? Bacteria’s DNA is inside the cell.”

It turned out that gonorrhoea, campylobacter and cholera also make ligase E, like Williamson’s cold-loving bacteria. The discovery has turned into an endeavour that could tackle antibiotic resistance in highly problematic diseases.

“If we could find a way to actually stop some of these repair processes that are allowing bacteria to pick up new bits of DNA, or we could interfere with that process, then the long-term idea would be can we interfere with that to help curb the spread of resistance?”

The potential benefits are obvious, but the discovery came from studying the natural world in a “blue-sky” way, meaning real-world applications weren’t known at first. “The journey would never have started if I hadn’t been able to get some funding and [without] the support of the university I was at in Norway. It’s so important that mechanisms like the Marsden Fund can continue to support this type of research.”

The fund administered by the Royal Society Te Apārangi faces successive cuts and the government in 2024 withdrew support for social sciences and humanities research.

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