Biology subjects

Friscic, T.

Publications and source records attributed to Friscic, T..

4 recordsLinked to original sources

bioRxiv2022

Efficient mechano-enzymatic hydrolysis of polylactic acid under moist-solid conditions.

Quantitative mechano-enzymatic depolymerisation of polylactic acid to lactic acid was achieved at 55{degrees}C using the Humicola insolens cutinase enzyme in moist-solid reaction mixtures. The resulting lactic acid was easily recovered, and the crude product was pure enough to be used in further synthesis of a value-added compound, a known benzimidazole-based drug precursor. The presented mechano-enzymatic depolymerisation strategy enables the closed-loop recycling of untreated polylactic acid under mild conditions, using a renewable, non-toxic catalyst and producing minimum solvent waste.

biochemistry↗

bioRxiv2022

Solid-state enzymatic hydrolysis of mixed PET-cotton textiles

Waste polyester textiles trap copious amounts of useful polymers, which are not recycled due to separation challenges and partial structural degradation during use and thermo-mechanical recycling. Chemical recycling of polyethylene terephthalate (PET) through depolymerization can provide a feedstock of recycled monomers to make "as-new" polymers, and reduce the accumulation of plastic waste in landfills. Enzymes are highly specific, renewable, environmentally benign catalysts, with hydrolases available that are active on common PET textile fibers and on cotton. The enzymatic PET recycling methods in development, however, have thus far been limited to clean, high-quality PET feedstocks, and most such processes require an energy-intensive melt-amorphization step ahead of enzymatic depolymerization. Here we report that high-crystallinity PET in mixed PET/cotton textiles can be directly and selectively depolymerized to terephthalic acid (TPA) by using a commercial cutinase from Humicola insolens under moist-solid reaction conditions, affording up to 30 {+/-} 2% yield of TPA. The process is readily combined with cotton depolymerisation through simultaneous application of cellulase enzymes (CTec2(R)), providing up to 83 {+/-} 4% yield of glucose without any negative influence on the TPA yield. The herein presented selective and/or simultaneous enzymatic hydrolysis of PET/cotton textiles in solid reaction mixtures can expand the biocatalytic recycling processes of PET to less-valuable waste materials, and significantly increase its profitability through operating at very high solid-loading (40%), without the need for melt-amorphization.

biochemistry↗

bioRxiv2020

Clean Enzymatic depolymerization of highly crystalline polyethylene terephthalate in moist-solid reaction mixtures

Less than 9% of the plastic produced is recycled after use, contributing to the global plastic pollution problem. While polyethylene terephthalate (PET) is one of the most common plastics, its thermomechanical recycling generates a material of lesser quality. Enzymes are highly selective, renewable catalysts active at mild temperatures; however, the current consensus is that they lack activity towards the more crystalline forms of PET. We report here that when used in moist-solid reaction mixtures instead of the typical dilute aqueous solutions, enzymes can directly depolymerize high crystallinity PET in 13-fold higher space-time yield and a 15-fold higher enzyme efficiency than prior reports. Further, this process shows a 26-fold selectivity for terephthalic acid over other hydrolysis products, which allows the direct synthesis of UiO-66 metal-organic framework.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biochemistry↗

bioRxiv2020

Rapid mechanoenzymatic saccharification of lignocellulosic biomass without bulk water or chemical pre-treatment

Lignocellulosic material is an abundant renewable resource with the potential to replace petroleum as a feedstock for the production of fuels and chemicals. The large scale deployment of biomass saccharification is, however, hampered by the necessity to use aggressive reagents and conditions, formation of side-products, and the difficulty to reach elevated monosaccharide concentrations in the crude product. Herein we report the high efficacy of Reactive Aging (or Raging, a technique where enzymatic reaction mixtures, without any bulk aqueous or organic solvent, are treated to multiple cycles of milling and aging) for gram-scale saccharification of raw lignocellulosic biomass samples from different agricultural sources (corn stover, wheat straw, and sugarcane bagasse). The solvent-free enzymatic conversion of lignocellulosic biomass was found to proceed in excellent yields (ca. 90%) at protein loadings as low as 2% w/w, without the need for any prior chemical pre-treatment or high temperatures, to produce highly concentrated (molar) monosaccharides. This crude product of mechanoenzymatic depolymerization is non-toxic to bacteria and can be used as a carbon source for bacterial growth.

biochemistry↗