Comparative Performance of PETase as a Function of Reaction Conditions, Substrate Properties, and Product Accumulation

Abstract

Invited for this month′s cover is the BOTTLE Consortium, featuring Gregg Beckham's laboratory from NREL and John McGeehan's laboratory from the University of Portsmouth. The cover image shows the application of poly(ethylene terephthalate) (PET) hydrolase enzymes on post‐consumer waste plastic, towards the development of an enzymatic PET recycling strategy. The Full Paper itself is available at 10.1002/cssc.202101932.

Expanding Plastics Recycling Technologies: Chemical Aspects, Technology Status and Challenges

“…Namely, it was estimated that approximately half of the energy input and GHG emissions arise from substrate pretreatment, which was modeled as thermal extrusion and cryo-grinding to yield micronized, amorphous PET. The development of enzymatic systems that can deconstruct crystalline substrates, which has been highlighted by studies as a major need for the field, 805,817,[819][820] would thus be a major step forward for this approach. Secondly, EG recovery from water was estimated to roughly equate to the other half of energy use and GHG emissions.…”

Conversion of polyethylene terephthalate into pure terephthalic acid through synergy between a solid-degrading cutinase and a reaction intermediate-hydrolysing carboxylesterase

“…We would also like to mention that it is accepted in the field of PET degradation that enzymes that are easily produced in large amounts, soluble at high concentrations and stable at high temperatures (reducing requirements for replenishment), significantly reduce the cost factor associated with degradation. 41 It is also known that the use of temperatures in the range of 40-80 °C does not add anything to energy costs associated with other extant processes for PET degradation through a combination of mechanical and chemical means. 41 The new element added in this paper, to ongoing research and development involving LCC, is the enzyme TTCE.…”

“…41 It is also known that the use of temperatures in the range of 40-80 °C does not add anything to energy costs associated with other extant processes for PET degradation through a combination of mechanical and chemical means. 41 The new element added in this paper, to ongoing research and development involving LCC, is the enzyme TTCE. We have found that TTCE is produced at significantly higher yields over LCC (Fig.…”

“…This need can appear to be fulfilled by a recombinant system imitating the natural system present in I. sakaiensis (a mesophile bacterium), in which a PETase (capable of degrading PET, OETs, and BHET) cooperates with a MHETase (capable of degrading MHET). 40 Unfortunately, (i) both enzymes undergo facile denaturation, 5,7,41 at temperatures below the known T g s of semi-crystalline PET, 19,42 making this system useful mainly for the degradation of amorphous PET; (ii) TPA is generated in 40-60 times lower yield than that of the best cutinases by this system. 7,43 In light of the above, we present here a novel two-enzyme system, consisting of a cutinase, LCC [derived from a metagenomic library derived from a leaf-branch compost], and a thermostable carboxylesterase, TTCE [Thermus thermophilus carboxylesterase, cloned from strain HB8; protein ID TT1662; RCSB ID 1UFO].…”

Expanding Plastics Recycling Technologies: Chemical Aspects, Technology Status and Challenges

“…Namely, it was estimated that approximately half of the energy input and GHG emissions arise from substrate pretreatment, which was modeled as thermal extrusion and cryo-grinding to yield micronized, amorphous PET. The development of enzymatic systems that can deconstruct crystalline substrates, which has been highlighted by studies as a major need for the field, 786,798,[800][801] would thus be a major step forward for this approach. Secondly, EG recovery from water was estimated to roughly equate to the other half of energy use and GHG emissions.…”