Student research project looks at how different diets affect gut bacteria in cockroaches

By University Advancement and Communications Posted: December 8, 2020 2:00 p.m.

Dr. Mel Hart, Faraz Khan, and Dr. Maria Davis
Dr. Mel Hart, Faraz Khan, and Dr. Maria Davis Photo: University Advancement and Communications

In 2019, biology lab instructors Maria Davis, Heather Dietz, and Mel Hart put their heads together to come up with an independent research project for a student who needed a course that was no longer offered. The result was an interdisciplinary, hands-on experience that touched on each of their respective areas of expertise – genetics and DNA sequencing, microbiology, and entomology. Through this research project, the student learned how to rear insects and culture their gut bacteria. When the semester came to an end, Dr. Davis and Dr. Hart knew that there was so much more research that could be done.

They encouraged third-year biology student Faraz Khan to apply for the Natural Sciences and Engineering Research Council (NSERC) of Canada’s Undergraduate Student Research Award, which would give him the opportunity to continue the research project over the course of the summer. This time, they wanted to focus on the effects that diet can have on the gut microbial community of Blaberus discoidalis, a species of cockroach commonly used as reptile food.

Khan holding on to a live cockroach
Credit: UAC

“You are what you eat; this is true for all organisms. We are very invested in our pets and we want to make sure what we are feeding them will keep them healthy,” says Dr. Davis. “For example, bearded dragons need very specific caloric intakes and micro and macro nutrients, which come from what they’re eating.”

The award gave Khan the opportunity to research cockroach gut microbiomes throughout the summer under the supervision of Drs. Davis and Hart. He has continued his research in the Fall 2020 semester in his Independent Research in Biology (BIOL 396) course.

Due to the COVID-19 pandemic, Khan started the summer at home doing literature searches, looking at similar research projects, and creating a plan for the rest of the summer. Once permitted to return to the lab, he joined Drs. Davis and Hart (and 144 cockroaches) and began to put his plan into action.

The research team set up nine insect cages, each with eight female and eight male cockroaches. They fed the cockroaches one of three different diets: sweet potato, Cheese Pleesers, or a mixture of fruit and vegetables.

“Quite often, this species of cockroach is fed to pet reptiles, and pet owners will do gut loading, which means they feed specific nutrients to the cockroach so that their reptile also gets the nutrients,” says Khan. “We wanted to see whether these practices impacted the gut community, and whether it translated to any bacterial effects that your reptile will then be ingesting. It’s kind of like a reptile probiotic.”

After the cockroaches ate their designated diets for 21 days, it was time to dissect them. Drs. Davis and Hart joined Khan to dissect all 144 cockroaches in one day. This included removing the entire gut, cutting it into the foregut, midgut, and hindgut, and freezing those sections in liquid nitrogen. Khan then focused on extracting DNA from the hindgut portion to look at the bacterium.

A cockroach eating sweet potato
Photo by Dr. Mel Hart

Coincidentally, Kirsten Palmier, a PhD student pursuing a doctoral degree in biology, was doing a similar research project in the summer, working on extracting and exploring the gut community in bumblebees. Khan was able to adapt Palmier’s protocol for extracting the DNA from bumblebees and apply it to the much larger cockroach guts. He extracted all of the gut samples and removed any debris and remaining proteins, which left him with pure DNA. The research team sent off the DNA for DNA sequencing to determine what bacteria were in the guts. Khan has spent time in his Independent Research in Biology (BIOL 396) class looking at the DNA sequencing data and learning how to analyze it.

“There are so many open-ended things to do with this data. This is where you can compare the different diets and how it affects the bacteria,” says Khan. ‘You could even analyze the other two sections of the gut.”

Right now, Khan is focused on completing his Bachelor of Science (BSc) in biology, and considering pursuing a master’s degree. He says this experience has made pursuing a master’s degree more approachable; prior to working on this research project, he didn’t really think of it as being an option.

Both Drs. Davis and Hart credit the Research Office for ensuring research projects such as this one can safely take place on campus during the pandemic. They also recognize Dr. Doug Farenick, Dean of Science, for being extremely supportive of student research projects. Such projects are key to the future successes of our undergraduates.

“As a Lab Instructor, I care most about our student's learning experience, and preparing them for life after their undergraduate career. Research such as this allows students a rich learning experience that not all universities can offer their undergraduates,” says Dr. Hart. “What they learn in these projects add to their skill set, making them more successful competitors in the job market once they leave our doors.”

The next round of NSERC Undergraduate Student Research Award applications are due in January. Students interesting in applying can find more information and an application on the NSERC website


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