Method for degrading PET plastics by utilizing synergistic effect of two enzymes

Abstract

The invention discloses a method for degrading PET plastics by utilizing the synergistic effect of two enzymes, which comprises the following steps of putting the PET plastics into a mixed enzyme solution of PETase enzyme and MHETase enzyme, and carrying out degradation reaction at 30 DEG C for 48 hours, with the enzyme activity unit ratio of the PETase enzyme to the MHETase enzyme being 3: 1. The PET plastics can be quickly degraded into two monomers, namely terephthalic acid and ethylene glycol. Compared with bacteria Ideonella sakaiensis and a degrading enzyme which is independently used, the degradation rate is obviously improved, the reaction condition is mild, the reaction process is safe, and no secondary pollution is generated. Especially, the gene of the PETase enzyme and the gene of the MHETase enzyme are subjected to codon optimization to construct recombinant escherichia coli capable of expressing the MHETase enzyme and the PETase enzyme, expression is carried out under the optimized condition, and the degradation speed of PET can be further increased.

Description

technical field [0001] The invention relates to the technical field of genetic engineering, in particular to a method for degrading PET plastics through the synergistic action of two enzymes. Background technique [0002] Since plastic was first synthesized in the 18th century, it has been widely used in various fields. In 2016 alone, the total global plastic production has reached 335 million tons. Polyethylene terephthalate (PET) is one of the most common plastics, accounting for about one-fifth of global plastic production. Since plastics are artificially synthesized high polymers with compact texture and difficult to degrade in the natural environment, the previous treatment methods were landfill or incineration, which caused huge pollution to the environment. In 2016, Japanese scientists discovered a bacterium Ideonella sakaiensis 201-F6 that feeds on PET plastic, but the bacterium grows slowly and has low degradation efficiency. (Yoshida S , Hiraga K , Takehana T , T...

AI Technical Summary

Problems solved by technology

Since plastics are artificially synthesized high polymers with compact texture and difficult to degrade in the natural environment, the previous treatment methods were landfill or incineration, which caused huge pollution to the environment

In 2016, Japanese scientists discovered a bacterium Ideonella sakaiensis 201-F6 that feeds on PET plastics, but this bacterium grows slowly and has low degradation efficiency

Although the degradation rate has been improved compared with the bacteria Ideonella sakaiensis 201-F6, there is still the problem of low degradation efficiency

[0004] Later research found that there are two enzymes PETase and MHETase related to PET degradation in the bacteria Ideonella sakaiensis, but the degradation of PET plastics is degraded in stages, that is, the PETase enzyme is used alone in the first stage to convert PET into single (2-Hydroxyethyl) terephthalate (MHET), using MHETase alone in the second stage, hydrolyzing MHET to obtain terephthalic acid and ethylene glycol, still has not completely solved the phenomenon of slow enzyme degradation of PET plastics, it is difficult Application in industry

[0005] So far, there is no report on the combination of two enzymes for the degradation of PET plastics

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