AUTHOR=Khruengsai Sarunpron , Sripahco Teerapong , Pripdeevech Patcharee 

TITLE=Biodegradation of Polyester Polyurethane by Embarria clematidis

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.874842

DOI=10.3389/fmicb.2022.874842

ISSN=1664-302X

ABSTRACT=<p>Polyester urethanes (PUR) are widely used in industries and have led to a worldwide plastic waste problem. Thus, novel solutions for PUR degradation are required to reduce environmental pollution. This work investigates the PUR biodegradation efficiency of 33 fungal species using a polyester-polyurethane colloid branded Impranil DLN (Impranil) compared to <italic>Aspergillus niger</italic>, which served as the positive control. The biodegradation is evaluated based on its ability to clear Impranil in media. Eleven fungi can clear Impranil in both solid- and liquid-medium assays. The highest degradation was attributed to <italic>Embarria clematidis</italic> cultured with Impranil as a carbon source. The degradation was confirmed by the Sturm test, Fourier-transform infrared (FTIR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS). From the Sturm test, CO<sub>2</sub> at a concentration of 0.85 g/L was found in <italic>E. clematidis</italic> cultured with 150 mL of Impranil solution after a 2-week incubation period while the CO<sub>2</sub> at a concentration of 0.53 g/L was detected from <italic>A. niger</italic> in the same conditions. The biodegradation was further confirmed by evaluating the clearance percentage of supernatant of <italic>E. clematidis</italic> and <italic>A. niger</italic> culturing with Impranil from the Sturm test. The clearance percentage of <italic>E. clematidis</italic> and <italic>A. niger</italic> supernatant was 88.84 and 48.97%, respectively. Moreover, the degradation of soft segment and breakdown of ester linkages were observed, as evidenced by the decrease of the carbonyl (1,715 cm<sup>–1</sup>) and N-H stretching (1,340 cm<sup>–1</sup> and 1,020 cm<sup>–1</sup>) FTIR spectral peaks, respectively. GC-MS detected 3Z-heptenol, 5Z-octenol, 2E,4E-hexadienol acetate, and 3E,6Z-nonadienol as degradation products from the <italic>E. clematidis</italic> culture supernatant. This fungus was screened for its ability to produce extracellular esterase, protease, and urease enzymes. Extracellular esterase, very low urease, and no protease activities were detected in the culture supernatant of <italic>E. clematidis</italic> in the presence of Impranil. <italic>E. clematidis</italic> can degrade Impranil partially <italic>via</italic> hydrolysis of ester linkages by cell-bound esterases at a considerable rate without any prior treatment. This fungus not only degraded Impranil but also mineralized them into CO<sub>2</sub> and H<sub>2</sub>O. <italic>E. clematidis</italic> can be applied in the process of biochemical depolymerization of PUR for the pure monomers recycling.</p>