The research aimed to select the optimal mineral salt medium (MSM) for low-density polyethylene (LDPE) biodegradation by the strain Pseudomonas fluorescens CNM-PFB-01. Four culture media were selected, which differed in salt content, N:P and C:N ratio. After 40 days of submerged cultivation, the following parameters were determined: catalase activity, pH of culture media, biomass accumulation, rate of degradation and the tensile tests of LDPE. It was observed that the strain is catalase-negative both in the control without LDPE and in the presence of LDPE. A weak positive reaction was established only on MSM 4 supplemented with LDPE. In the presence of polyethylene, the pH of the media increased, especially on the MSM 4 - by 0.6 units. The addition of polyethylene to the growth media stimulated the bacterial biomass accumulation by 2-3.6 times. The degradation rate of polyethylene films ranged from 0.37% to 0.86% depending on the culture medium. The tensile test showed increased elasticity of the plastic in the variants treated with bacterial strain. In conclusion, in order to stimulate the biodegradation of LDPE by the strain P. fluorescens CNM-PFB-01, the medium MSM 4 (N: P ratio 4.30: 1 and C: N ratio 0.29: 1) was selected.