Microplastics–Lactic Acid Bacteria Interplay: Alterations in Probiotic Function and Microplastic Integrity
This study evaluated the potential reciprocal effects associated with interactions between lactic acid bacteria (LAB) with probiotic potential and two common microplastics, polyethylene terephthalate (PET) and poly(vinyl alcohol) (PVA), under controlled in vitro conditions. Bacterial growth, adhesion-related properties (autoaggregation, hydrophobicity, and coaggregation), safety-related traits (hemolytic activity and mucin degradation), antioxidant activity (ABTS scavenging and oxidative hemolysis inhibition), and anti-inflammatory activity (lipoxygenase and trypsin inhibition) were analyzed, along with structural and thermal changes in microplastics. Microplastic exposure did not affect bacterial growth (p > 0.05) but reduced autoaggregation and hydrophobicity (p < 0.05). None of the strains showed hemolytic activity, although mucin degradation increased. Antioxidant and anti-inflammatory activities decreased (p < 0.05). In addition, FTIR, thermal analysis, and microscopy revealed changes in the chemical composition, thermal behavior, and morphology of PET and PVA after interaction with LAB. Overall, microplastics modulate key probiotic-associated functions in LAB without compromising bacterial viability, while selected strains remain partially resilient and induce physicochemical changes in microplastic particles.