Case of endangered aquarium medicine
For months, vets put drugs in the animal quarantine habitats at Chicago’s Shedd Aquarium, making sure animals entering the building did not bring parasites or dangerous pathogens with them. And for months the drug kept fading away. Where was he going? Who was taking it? And what was their motive?
To help solve this classic thriller mystery, researchers at the Shedd Aquarium have teamed up with microbiologists at Northwestern University to collect clues, follow leads and ultimately find the culprit.
After performing microbial and chemical analyzes on samples from saltwater aquarium systems, the team discovered that it was not just one culprit, but many: a family of microbes hungry for nitrogen.
“Carbon, nitrogen, oxygen and phosphorus are basic necessities that everyone needs to live,” said Erica M. Hartmann of Northwestern, who led the study. “In this case, it seems that the microbes were using the drug as a source of nitrogen. When we looked at the degradation of the drug, we found that the piece of the molecule containing the nitrogen was gone. It would be the equivalent of just eating the pickles from a cheeseburger and leaving the rest behind.
The research was published online Saturday (October 2) in the journal Science of the Total Environment.
An expert in indoor microbiology and chemistry, Hartmann is an assistant professor of civil and environmental engineering at the McCormick School of Engineering at Northwestern.
When a new animal enters the Shedd Aquarium, it must first undergo a quarantine process before entering its permanent residence. This allows aquarium vets to observe the animal for potentially contagious diseases or parasites without risking harm to other animals in the facility.
“Shedd Aquarium’s behind-the-scenes quarantine habitats are a first stop for animals entering the building, allowing us to welcome them safely in a way to ensure that outside pathogens are not introduced into the animals that are entering the building. already live in Shedd, ”said Dr. Bill. Van Bonn, vice president of animal health at the Shedd Aquarium and co-author of the study. “We are grateful to have partnered with Northwestern University to scientifically explore what is happening in our quarantine habitats at the microbial level to inform about how we manage them and continue to provide optimal welfare for the animals we take.” care.”
Antiparasitic drug “mysteriously disappeared”
During this quarantine process, all animals are given chloroquine phosphate, a common pest control drug. Veterinarians proactively add it directly to water as a pharmaceutical bath to treat a variety of ailments. After adding chloroquine to the water, aquarists then measure the concentration of the drug. That’s when they realized something was wrong.
“They have to maintain a certain concentration in habitats to effectively treat animals,” Hartmann said. “But they noticed that the chloroquine mysteriously disappeared. They would add the correct amount, then measure it out and the concentration would be much lower than expected – to the point that it wouldn’t work anymore. “
754Microbes identified by Hartmann’s laboratory
Aquarists at the Shedd Aquarium collected water samples and swabs and sent them to Hartmann’s lab. Swabs were taken from the sides of the habitats as well as from the pipes entering and leaving them. In total, the team found around 754 different microbes.
“There are microbes in the water, obviously, but there are also microbes that stick to the walls of surfaces,” Hartmann said. “If you’ve ever had a home aquarium, you’ve probably noticed grime growing on the sides. People sometimes add snails or algae-eating fish to help clean up the sides. So we wanted to study everything that was in the water and what was stuck to the walls of the surfaces. “
Study the “leftovers” of the meal
By studying these samples, the Northwestern and Shedd Aquarium teams first determined that the microbes were killing the drug and then located the responsible microbes. Hartmann’s team cultured the collected microbes and then provided chloroquine as the sole carbon source. When the results of this experiment were inconclusive, the team performed sensitive analytical chemistry to study the degraded chloroquine.
“If the chloroquine was consumed, we were basically looking at the leftovers,” Hartmann said. “That’s when we realized that nitrogen was the main driver.
The unusual suspects
Of the 754 microbes collected, the researchers narrowed it down to at least 21 different guilty suspects – belonging to the phyla Actinobacteria, Bacteroidetes, Chloroflexi, and Proteobacteria – living inside habitat outlet pipes. Some of the microbes even appear to be brand new and never studied before.
“We couldn’t identify a single culprit, but we could isolate the specific location,” Hartmann said. “Our results determined that simply flushing quarantine habitats with fresh water would not be enough to solve the problem because the responsible microbes cling to the sides of the pipes.”
Hartmann said the pipes may need to be cleaned or replaced in order to prevent the chloroquine from wiping out in the future. Another potential solution could be to switch regularly between fresh and salt water, as microbes are usually sensitive to one or the other.
“Everyone at Shedd Aquarium is obviously very committed to the health and welfare of the animals they house and is very enthusiastic about the research,” Hartmann said. “It was really cool working with them because we were able to help the animals and maybe discovered new organisms.”
The study, “Towards Understanding the Microbial Degradation of Chloroquine in Large Saltwater Systems,” was supported by the Searle Leadership Fund and the Helen V. Brach Foundation.