December 9, 2022

Plastic debris in the ocean can produce useful antibiotics •

Scientists estimate that between 5 and 13 million metric tons of plastic pollution enter the oceans every year, ranging from large floating chunks to microplastics with a massive combined surface area. Microbes easily attach to the surfaces of these plastic debris and form floating or suspended ecosystems rich in biomass. But, as the attachment space is limited on the plastic fragments, it is likely that competition will exist between the microbes. Under such conditions, it is not uncommon for microbes to produce antibiotics to gain a competitive advantage.

To determine if these tiny inhabitants of the plastisphere produce antibiotics that might be of interest, a student-led research study has been set up under the auspices of the National University and in collaboration with the Scripps Institution of Oceanography. The researchers modified the tiny earth citizen science approach (developed by Dr. Jo Handelsman) to marine conditions. They incubated high- and low-density polyethylene plastic (the type commonly seen in grocery bags) in water near Scripps Pier in La Jolla, Calif., for 90 days, then cultured and tested the microbes in laboratory.

Researchers have isolated five antibiotic-producing bacteria from ocean plastic, including strains of Bacillus, Phaeobacter and vibrio. They tested the antibiotics produced by these bacteria against a variety of Gram-positive and negative microbes, and found the antibiotic isolates to be effective against bacteria commonly used in the laboratory, as well as two antibiotic-resistant strains.

“Given the current antibiotic crisis and the rise of superbugs, it is essential to seek alternative sources of new antibiotics,” said study lead author Andrea Price of National University. “We hope to expand this project and further characterize the microbes and the antibiotics they produce.”

This project was part of a STEM education project funded by the National Science Foundation. The research results will be presented at the American Society for Microbiology conference in Washington, DC, to be held June 9-13, 2022.

By Alison Bosman, Personal editor