Microplastic particles (MPs) are widely distributed pollutants in the environment. While a growing number of studies have shown that MPs are toxic to plant and animal life, systemic efforts to reduce their presence have been scarce. Low-density polyethylene (LDPE) and polystyrene (PS) are one of the most common among all plastic-forming MPs. In this study, pure bacterial strains, Bacillus licheniformis and Lysinibacillus <br /> massiliensis, and a mixed bacterial culture of Delftia acidovorans and Bacillus sp., were <br /> used for biodegradation of LDPE and PS microplastics. Biodegradation of MP-PS and <br /> MP-LDPE of particle size 300 – 500 μm was carried out under batch operating conditions at a temperature of 25 ± 2 °C, pH values of 7.15, and 160 rpm during 22 days. The <br /> obtained results showed that mixed bacterial cultures degraded MP-LDPE and MP-PS <br /> better than pure bacterial cultures, and the biodegradation efficiency was higher for MP-LDPE than for MP-PS, as indicated by greater reduction in peak intensity and spectral <br /> deformation, higher colony forming unit (CFU), and inorganic carbon (IC) values.