Screening of cultivation media for LDPE biodegradation by Penicillium verrucosum CNM-FP-02

The paper’s aim was to select the optimal mineral medium for LDPE biodegradation by the strain
Penicillium verrucosum CNM-FP-02. It was selected 5 mineral salt media (MSM), which differed in
salt content and N/P ratio. After 40 days of submerged cultivation, the following parameters were
determined: catalase activity and pH of cultural media, biomass accumulation, rate of LDPE
degradation, optical microscopy, and the tensile testing of polyethylene. It was observed that
catalase activity on all media, except MSM 4, was higher in the presence of LDPE. The addition of
polyethylene to the growth media stimulated the fungal biomass accumulation by 19.3-93.1% (4
media out of 5 tested). The percentage of degradation of LDPE films was different, depending on
the culture medium, from 0.41% to 0.92%. The most active LDPE films were degraded on medium
MSM 2. Visualization of plastic strips under an optical microscope revealed the immobilization of
the microorganism and the damage on the polyethylene surface. The tensile test showed increased
elasticity of the plastic in the variants treated with fungal strain. In conclusion, in order to stimulate
the biodegradation of LDPE by the strain P. verrucosum CNM-FP-02, the medium MSM 2 (N/P
ratio 1:1) was selected.