Fermentative production of cadaverine from renewable resources may support a sustainable biorefinery process to produce carbon-neutral nylons such as biopolyamide 510 (PA510). Cost-competitive production of cadaverine is a key factor in the successful commercialization of PA510. In this study, an integrated biological and chemical process involving cadaverine biosynthesis, purification, and its polymerization with sebacic acid was developed to produce bio-PA510. To stably express ldcC from Escherichia coli in an engineered Corynebacterium glutamicum PKC strain, an expired industrial L-lysine-producing strain, ldcC, was integrated into the chromosome of the C. glutamicum PKC strain by disrupting lysE and controlling its expression via a strong synthetic H30 promoter. Cadaverine was produced at a concentration of 103.78 g/L, the highest titer to date, from glucose by fed-batch culture of this engineered C. glutamgicum PKC strain. Fermentation-derived cadaverine was purified to polymer-grade biocadaverine with high purity (99%) by solvent extraction with chloroform and two-step distillation. Finally, biobased PA510 with good thermal properties (T m 215 °C and T c 158 °C) was produced by polymerization of purified cadaverine with sebacic acid. The hybrid biorefinery process combining biological and chemical processes demonstrated in this study is a useful platform for producing biobased chemicals and polymers.

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Poly(ethylene terephthalate) (PET), composed of terephthalic acid (TPA) and ethylene glycol (EG), is the most commonly produced polyester. Unrecycled PET waste causes serious environmental problems. To increase the PET recycling rate, the upcycling of PET into products that are higher value than PET is desired. In this study, the feasibility of biological valorization of PET for its upcycling was experimentally evaluated. Among the two monomers obtained from the chemical hydrolysis of PET, TPA was biologically converted to five different aromatics and aromatic-derived compounds by using whole-cell catalysts comprising Escherichia coli engineered to express necessary metabolic enzymes for biosynthetic routes for converting TPA. These five higher-value products from TPA, gallic acid, pyrogallol, catechol, muconic acid, and vanillic acid were synthesized via protocatechuic acid as the key intermediate at relatively high molar conversion yields, 32.7−92.5%. The other monomer from PET, EG, was fermented to glycolic acid, a cosmetic ingredient. This is the first experimental validation of producing various higher-value chemicals from PET monomers.

The use of microarray technology enables definition of complex genetic changes underlying distinct phases of the cellular response to retinal injury. The early response clusters genes associate with the transcriptional regulation of the wound-healing process and cell death. Most of the genes in the late, sustained response appear to be associated with reactive gliosis.

In this study, we developed recombinant Escherichia coli strains expressing Lactococcus lactis subsp. lactis Il1403 glutamate decarboxylase (GadB) for the production of GABA from glutamate monosodium salt (MSG). Syntheses of GABA from MSG were examined by employing recombinant E. coli XL1-Blue as a whole cell biocatalyst in buffer solution. By increasing the concentration of E. coli XL1-Blue expressing GadB from the OD₆₀₀ of 2-10, the concentration and conversion yield of GABA produced from 10 g/L of MSG could be increased from 4.3 to 4.8 g/L and from 70 to 78 %, respectively. Furthermore, E. coli XL1-Blue expressing GadB highly concentrated to the OD₆₀₀ of 100 produced 76.2 g/L of GABA from 200 g/L of MSG with 62.4 % of GABA yield. Finally, nylon 4 could be synthesized by the bulk polymerization using 2-pyrrolidone that was prepared from microbially synthesized GABA by the reaction with Al₂O₃ as catalyst in toluene with the yield of 96 %.