In Vitro Evaluation of Polypropylene Microplastic Biodegradation Potential by the Probiotic Bifidobacterium Species

Polypropylene (PP) is widely used, but its fragmentation into microplastics raises concerns about environmental accumulation and potential human exposure through ingestion and medical settings. These microplastics may disrupt microbiota composition and intestinal functions, highlighting the need to explore microbial interactions and biodegradation potential. Although probiotics are increasingly recognized for their benefits to gut health, their potential to degrade microplastics, particularly PP, remains largely unexplored. To address this gap, the present study evaluates the ability of Bifidobacterium bifidum BCMC® 12130, Bifidobacterium longum BCMC® 02120, and Bifidobacterium longum subsp. infantis BCMC® 02129 to biodegrade PP powder and commercially available PP film under controlled laboratory conditions. Preliminary concentration screening with Bifidobacterium longum BCMC® 02120 showed the greatest apparent bacterial growth response at 0.10% (w/v) PP. For the subsequent 30-day exposure experiment, however, PP was standardized at 0.01% (w/v). Following incubation at 25 ± 2 °C with agitation, changes in recovered PP mass and surface morphology were assessed. Among the strains tested, B. longum BCMC® 02120 exhibited the greatest reduction in recovered PP powder mass, with an 86.7% decrease after 30 days (p < 0.05). Scanning electron microscopy revealed dense biofilm formation alongside surface roughening, voids, and erosion, consistent with microbial colonization and deterioration of the polymer surface. Energy-dispersive X-ray spectroscopy showed a decrease in surface carbon content from 92.62% to 90.00% and from 7.38% to 10.00%, respectively; however, these changes were not statistically significant. Together, these preliminary findings suggest that the probiotic strain B. longum BCMC® 02120 has potential for PP microplastic biodegradation. Further studies are needed to confirm polymer breakdown and determine whether this activity could help mitigate microplastic-related effects on gut health.