Odd Jobs: Dr Dog Poo

If anybody knows how to get their hands dirty, it is Emily Bryson, PhD student at Central Queensland University.

“I really want, when I graduate, to be known as Dr dog poo,” says Bryson.

Asked what her expertise is, she wittily replies: “Maybe canine fecal decompologist, with a horticultural sub-specialty.”

Bryson is working on a PhD project to determine how dog poo breaks down in compost, and whether this is pathogenic to humans and worms. This research falls under the umbrella of permaculture, which is understudied, considering its implications in agriculture.

“I think with permaculture, there’s a lot of collected knowledge and a lot of it is anecdotal,” Bryson explains. “If it’s research based, it hasn’t necessarily been either scientifically peer reviewed or has not been labelled as permaculture.

“There really hasn’t been a lot of robust, evidence-based science around it. And I think that’s a shame because one of the guiding principles around permaculture is that there’s no blanket solution for problems.”

Emily bryson and her lab assistant and sample donator, bailey.
Emily Bryson and her lab assistant and sample donator, Bailey. Credit: Emily Bryson.

Byrson fell into the field of study naturally. It had both practical applications that she could see in her life, and was a whole area of science that had yet to be explored.

“I’m a dog owner,” she says, describing why she noticed the data gap, “and I am really, really conscious about my waste and where it goes and what I do with it. And that’s just something that’s been evolving over the years.”

One of the major hurdles of studying dog poo is collecting samples. For a renewable resource, usable, uncontaminated dog-poo samples are rare, and that’s not even considering how few people are actually willing to donate their doggies’ doodoo.

“I need a big sample of different diets, with different breeds and different ages,” Bryson says. “So I went to dog daycare.

“The staff who work there are really good about hygiene, so when they see a poo, it [is picked] straight up. So, I thought, if they’re collecting that poo anyway, they could give it to me, and I could mix it up and use it in my study. So I [asked].”

Of course, there’s another star donator – who set the whole project off in the first place.

“My dog’s name is Bailey,” gushes Bryson. “He’s my research assistant.”

“He’s probably been the most consistent, ah, physical contributor to my study so far. He has diligently been giving me his poo over the past six months.”

Bryson’s research is a combination of multiple areas of science: microbiology, genetics, chemistry, ecology and biology are all considered, because the use of compost is multifaceted and holistic.

One of the first things she needed to establish was what variety of pathogens were in dog poo in the first place, to see whether any of these could harm humans or compost worms.

Bryson's home lab
Bryson’s home lab. Credit: Emily Bryson.

She explains that she knew pathogens were there – all poo has pathogens – but identifying them was a difficult, long process.

“I [have been] doing microbial plate cultures,” she says. “I take a sample of the poo, mix it with some liquid, and sometimes an enrichment broth to make sure that I’m targeting a specific type of bacteria, and then I put a sample of that onto a plate and see what grows.”

This creates a nutrient-rich environment for microbes to grow in abundance, which helps the sample to grow big enough to visibly collect and isolate. She also laces the microbial plates with specific antibacterial agents to remove any extra ‘noise’ from other bacteria she isn’t interested in.

This selective media only takes her so far, though, especially as she is working with little prior knowledge and methodology because of how understudied the dog-poo pathogens are. Specifically, she’s looking for salmonella.

“Other things tend to swarm on the plates that I don’t want, so it’s a matter of repeating and repeating the test and finetuning the technique.”

Once bacteria has been isolated, “it goes away”, says Bryson. “It goes to another lab and they do DNA sequencing, and so they can tell me exactly whether it’s salmonella or not.”

She planned to split her time between being in the microbiology lab and out with her composting piles, because lab compost isn’t indicative of a real environment. She spends a huge chunk of time maintaining her compost to keep the experiment as controlled as possibly, as well has constantly assessing the health of the worms.

“I’m not actually in the lab that much,” she says. “The rest of the time I’m composting and gathering data so it’s [collecting] the physical, chemical stuff,” she says.

Unfortunately, this process isn’t representative of everything Bryson actually does, because unfortunate global events threw a spanner in the works and stranded her in a different state from her lab.

“Researchers are still holding their breath, particularly if they’ve got to travel,” she laments. “And that can be a bit tricky, particularly if you want to stay on track with your work. That’s been the same case with me.”

This at-home composting experiment heavily focuses on worm and soil health, to assess whether composted dog poo affects worms that are commonly used for composting.

“I’m also running a worm eco-toxicity trial. That [involves] looking at earthworms, [in this case a] specific type of earthworm called Eisenia fetida. These guys are kind of like the canary in the coal mine for soil health.

“It’s been tricky, I think, trying to set up a really robust scientific trial, from the same place that I live. There’s always, always things that you can’t predict. And one of the main things I couldn’t predict was gnats – fungus gnats.

“The compost inoculant that I put into the containers, as a sort of organic amendment compost, is chock full of a fungus because that’s really good for building soil. I didn’t realise at the time that this fungus would start to grow, and it would attract gnats.

Bryson sorting worms at home.
Bryson sorting worms at home. Credit: Emily Bryson.

“So, they got into some of the test containers that were specifically for replication and just started having a disco. And replicating like mad.”

The challenges of home research hasn’t deterred her, though; her driving thirst for knowledge in an area she loves keeps her going.

“I want to know all the things about compost,” she says. “I feel like I could spend three or four lifetimes, just studying compost. There’s so much to know! There’s so much variability of what you can compost, where it can be used, who’s doing different types of composting, and how this technology can be improved.”

This thirst is also fuelled by her creativity. Bryson came from an arts background, which, she believes, has given her extra tools to handle such an unconventional research topic – especially as she has to build her own composting apparatus to reflect what people in real life have access to.

“There’s a lot of creativity and, and empathy as well – thinking about the end users of my research,” she says.

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