Ruminants release methane because of the peculiar way they digest their food. Inside a cow’s foregut, which can contain more than 200 pounds of grass at any given time, fermentation of the food leads to the release of hydrogen, a byproduct that would slow down the fermentation. Microbes known as methanogens help the ruminants get rid of the excess hydrogen by producing methane gases that the animals release into the atmosphere.

In other animals known as hindgut fermenters, including humans  in which food is fermented after going through their stomachs  methane is sometimes released through flatulence, a fact that, Mr. Klieve said, has led to misunderstanding about his work

Image Australia has high per capita greenhouse gas emissions. Credit... The New York Times

“We’ve had to put up with that all the time,” Mr. Klieve said. “It comes from the front end! In the cow, it comes from the front end. But if you’re a hindgut fermenter, it goes the other way.”

Leading a visitor through the campus here, which is part of the University of Queensland and is about 60 miles west of Brisbane, the state capital, Mr. Klieve explained his interest in kangaroos.

Like cattle, kangaroos are also foregut fermenters. But instead of relying on methanogens to get rid of the unwanted hydrogen, kangaroos use different microbes that reduce hydrogen by producing not methane, but harmless acetic acids, the basis of vinegar. Could the microbes in the kangaroos be transplanted into cows? Could the right environment be created in cow stomachs so that the good microbes would outcompete the methanogens?

“If we can answer those questions, we’re moving toward being able to get it so that these animals are not producing methane,” Mr. Klieve said.