Heat-Treated Polyethylene Degradation in Presence of Extracellular Enzymes of Staphylococcus epidermidis

Abstract

Staphylococcus epidermidis BP/SU1 can survive in a mineral medium supplemented with shredded autoclaved commercial LDPE (Low density polyethylene) as well as heat cast pure LDPE as its only carbon source and degrade commercial LDPE as seen by scanning electron microscopy. The extracellular supernatant of both the cultures show over expression of the same two proteins compared with the glucose supplemented one and the one where there is no carbon source. Tryptic digestion of these proteins was followed by Matrix Assisted Laser Desorption and Ionization-Mass Spectroscopy (MALDI-MS). Comparative proteomic analysis yielded significant homology with two proteins originating from Staphylococcal origin, one of them was fructose-bisphosphate aldolase class 1 (AAW52952) and the other one was superoxide dismutase (AAO04839). The effects of these two proteins were studied separately, along with the extracellular exudates, on commercial LDPE with the help of Fourier Transform-Infra Red spectroscopy (FT-IR) and Atomic Force Microscopy (AFM). The effect of the same two proteins on pure LDPE is studied using GC-MS (Gas Chromatography- Mass Spectrometry). Light scattering experiments with the residual mineral media after the proteins have acted on the pure LDPE give evidence of increase in the size of particulate matter when these enzymes act on it.

Keywords: biodegradation, fructose-bisphosphate aldolase, polyethylene, Staphylococcus epidermidis, superoxide dismutase

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