Coloured scanning electron micrograph of Cladosporium species. Credit: Science Photo Library/Alamy Stock Photo

A fungus, isolated from microbe-infested floating debris of microplastics, can rapidly break down and reduce the weight of a polymer commonly used to make disposable plastic bags1.

Previously identified fungi slowly degraded plastics. To find a better option, researchers at Bharathisdasan University and the University of Madras in Chennai selected 33 fungi in a ‘plastisphere’ sample extracted from the city's garbage dumpsites and polluted water bodies.

Of these, 28 showed the ability to degrade low-density polyethylene (LDPE) films. They screened these fungi and identified Cladosporium sphaerospermum as the most potent. The scientists introduced a small piece of LDPE film into a fungus culture and compared it with an untreated LDPE film.

The fungus used mycelia, slender root-like structures, to attach to the film and secrete specific enzymes that converted the plastic polymers into small molecules. The film's structure collapsed, developing cracks, pits, and cavities. Its surface eroded and became rough.

These changes eventually reduced the plastic film's weight by 15.12% in a week and by 50% in 31 days. However, the untreated film showed no such changes or loss in weight.