Biodegradation of plastics by the phosphorus-solubilising cyanobacterium Chroococcus sp.

Plastics often contain additives such as flame retardants, plasticisers, and stabilisers, with phosphorus-based compounds playing a key role in microbial interactions. Most previous studies have focused on heterotrophic microbes targeting carbon backbones, but their degradation efficiency remains limited. This study examined the phosphorus-solubilising ability of autotrophic cyanobacteria carrying the phoD gene to weaken polypropylene (PP) and polyethylene terephthalate (PET). Plastic samples collected from the Aquatic Research Complex fishpond at Universiti Sains Malaysia were incubated with isolates and analysed using NBRIP medium, molybdenum blue assay, UV–Vis, FTIR, SEM, and tensile strength testing over 61 days. Of the five strains isolated, Chroococcus sp. solubilised phosphorus from both PP and PET, releasing phosphorus into the medium and reducing plastic surface phosphorus. Treated plastics exhibited surface roughness, reduced dry mass, and significant tensile strength loss. This is the first report of photosynthetic cyanobacteria promoting plastic degradation via phosphorus scavenging.