Engineered microorganisms for the deconstruction of polymers
Disclosed herein are engineered P. putida KT2440 co-expressing PETase and MHETase enzymes that selectively degrades PET into monomers, ethylene glycol and terephthalate (TPA). In another embodiment, disclosed herein are methods for making and using a highly efficient EG metabolizing P. putida KT2440 strain. Given that native P. putida does not have a TPA metabolic pathway, nor the proteins to transport TPA into the cell, the next metabolic engineering challenge for developing synthetic P. putida strain to plastic upcycling was enabling TPA catabolismin P. putida KT2440. TPA transporters and catabolic pathway have been characterized in several microorganisms including Comamonas sp. strain E6 and Rhodococcus jostii RHA1.
1 . A genetically modified Pseudomonas organism comprising at least two exogenous gene additions, wherein:
a first exogenous gene addition comprises a gene with a sequence that is at least 90% identical to SEQ ID NO: 1 and a second exogenous gene addition comprises a gene with a sequence that is at least 90% identical to SEQ ID NO: 2 and wherein the first exogenous gene encodes for a functional PETase comprising a secretion signal peptide and wherein the second exogenous gene encodes for a functional MHETase comprising a secretion signal peptide and wherein the exogenous genes are incorporated into the genome of the genetically modified Pseudomonas ; and wherein the genetically modified Pseudomonas organism metabolizes poly (ethylene terephthalate) (PET) to produce PET deconstruction products selected from the group consisting of bis(2-Hydroxyethyl) terephthalate, mono-(2-hydroxyethyl) terephthalate, terephthalate, ethylene glycol, β-ketoadipate, and muconate; and wherein the genetically modified Pseudomonas converts bis(2-hydroxyethyl) terephthalate to terephthalate at a rate that is at least three times the rate of a naturally occurring Pseudomonas.
2 . The genetically modified organism of claim 1 , wherein the exogenous genes are derived from Ideonella sakaiensis and codon optimized for expression in Pseudomonas.
3 . The genetically modified organism of claim 1 , wherein the genetically modified Pseudomonas organism is Pseudomonas putida.
4 . A method for the deconstruction of poly (ethylene terephthalate) (PET) comprising contacting poly (ethylene terephthalate) (PET) with the genetically modified organism of claim 1 to produce PET deconstruction products.
5 . The method of claim 4 , wherein the contacting is performed in minimal salt medium.
6 . A genetically modified Pseudomonas organism comprising at least two exogenous gene additions, wherein:
a first exogenous gene addition comprises a gene with a sequence that is at least 90% identical to SEQ ID NO: 1 and a second exogenous gene addition comprises a gene with a sequence that is at least 90% identical to SEQ ID NO: 2 and wherein the first exogenous gene encodes for a functional PETase comprising a secretion signal peptide and wherein the second exogenous gene encodes for a functional MHETase comprising a secretion signal peptide and wherein the exogenous genes are incorporated into the genome of the genetically modified Pseudomonas ; and wherein the genetically modified Pseudomonas organism metabolizes poly (ethylene terephthalate) (PET) to produce PET deconstruction products selected from the group consisting of bis(2-Hydroxyethyl) terephthalate, mono-(2-hydroxyethyl) terephthalate, terephthalate, ethylene glycol, β-ketoadipate, and muconate; and wherein the genetically modified Pseudomonas converts bis(2-hydroxyethyl) terephthalate to terephthalate at a rate that is at least three times the rate of a naturally occurring Pseudomonas ; and wherein the genetically modified Pseudomonas organism further comprises heterologous TPA transporters.
7 . The genetically modified organism of claim 6 further comprising catabolic gene clusters I or II.
8 . The genetically modified organism of claim 7 wherein the catabolic gene clusters I or II are from Comamonas sp. E6.
9 . The genetically modified organism of claim 7 capable of using TPA as a sole carbon source.
10 . The genetically modified organism of claim 9 wherein said organism is capable of metabolizing TPA at about 0.05 g L −1 h −1 .
11 . The genetically modified organism of claim 7 lacking a pcaIJ gene.
12 . The genetically modified organism of claim 11 that metabolizes TPA to β-ketoadipate.
13 . The genetically modified organism of claim 6 , wherein the exogenous genes are derived from Ideonella sakaiensis and codon optimized for expression in Pseudomonas.