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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 at10.1002/cssc.202101932. [ABSTRACT FROM AUTHOR]

Mixed plastics waste represents an abundant and largely untapped feedstock for the production of valuable products. The chemical diversity and complexity of these materials, however, present major barriers to realizing this opportunity. In this work, we show that metal-catalyzed autoxidation depolymerizes comingled polymers into a mixture of oxygenated small molecules that are advantaged substrates for biological conversion. We engineer a robust soil bacterium, Pseudomonas putida, to funnel these oxygenated compounds into a single exemplary chemical product, either b-ketoadipate or polyhydroxyalkanoates. This hybrid process establishes a strategy for the selective conversion of mixed plastics waste into useful chemical products. [ABSTRACT FROM AUTHOR]

Poly(ethylene terephthalate) (PET) is the most abundantly consumed synthetic polyester and accordingly a major source of plastic waste. The development of chemocatalytic approaches for PET depolymerization to monomers offers new options for open-loop upcycling of PET, which can leverage biological transformations to higher-value products. To that end, here we perform four sequential metabolic engineering efforts in Pseudomonas putida KT2440 to enable the conversion of PET glycolysis products via: (i) ethylene glycol utilization by constitutive expression of native genes, (ii) terephthalate (TPA) catabolism by expression of tphA2 II A3 II B II A1 II from Comamonas and tpaK from Rhodococcus jostii , (iii) bis(2-hydroxyethyl) terephthalate (BHET) hydrolysis to TPA by expression of PETase and MHETase from Ideonella sakaiensis , and (iv) BHET conversion to a performance-advantaged bioproduct, β-ketoadipic acid (βKA) by deletion of pcaIJ. Using this strain, we demonstrate production of 15.1 g/L βKA from BHET at 76% molar yield in bioreactors and conversion of catalytically depolymerized PET to βKA. Overall, this work highlights the potential of tandem catalytic deconstruction and biological conversion as a means to upcycle waste PET. • Enabled terephthalate (TPA) and bis(2-hydroxyethyl)TPA (BHET) catabolism in P. putida • Engineered conversion of BHET to β-ketoadipate (βKA), a performance-advantaged bioproduct • Achieved a titer of 15.1 g βKA/L at a 76% molar yield from commercial BHET • Demonstrated βKA production from glycolyzed poly(ethylene TPA) (PET) [ABSTRACT FROM AUTHOR]