Biodegradative Activities of Selected Environmental Fungi on a Polyester Polyurethane Varnish and Polyether Polyurethane Foams
Por:
Alvarez-Barragan, Joyce, Dominguez-Malfavon, Lilianha, Vargas-Suarez, Martin, Gonzalez-Hernandez, Ricardo, Aguilar-Osorio, Guillermo, Loza-Tavera, Herminia
Publicada:
1 sep 2016
Resumen:
Polyurethane (PU) is widely used in many aspects of modern life because
of its versatility and resistance. However, PU waste disposal generates
large problems, since it is slowly degraded, there are limited recycling
processes, and its destruction may generate toxic compounds. In this
work, we isolated fungal strains able to grow in mineral medium with a
polyester PU (PS-PU; Impranil DLN) or a polyether PU (PE-PU; Poly Lack)
varnish as the only carbon source. Of the eight best Impranil-degrading
strains, the six best degraders belonged to the Cladosporium
cladosporioides complex, including the species C. pseudocladosporioides,
C. tenuissimum, C. asperulatum, and C. montecillanum, and the two others
were identified as Aspergillus fumigatus and Penicillium chrysogenum.
The best Impranil degrader, C. pseudocladosporioides strain T1. PL. 1,
degraded up to 87% after 14 days of incubation. Fourier transform
infrared (FTIR) spectroscopy analysis of Impranil degradation by this
strain showed a loss of carbonyl groups (1,729 cm(-1)) and NOH bonds
(1,540 and 1,261 cm(-1)), and gas chromatography-mass spectrometry
(GC-MS) analysis showed a decrease in ester compounds and increase in
alcohols and hexane diisocyanate, indicating the hydrolysis of ester and
urethane bonds. Extracellular esterase and low urease, but not protease
activities were detected at 7 and 14 days of culture in Impranil. The
best eight Impranil-degrading fungi were also able to degrade solid
foams of the highly recalcitrant PE-PU type to different extents, with
the highest levels generating up to 65% of dry-weight losses not
previously reported. Scanning electron microscopy (SEM) analysis of
fungus-treated foams showed melted and thinner cell wall structures than
the non-fungus-treated ones, demonstrating fungal biodegradative action
on PE-PU.
IMPORTANCE
Polyurethane waste disposal has become a serious problem. In this work,
fungal strains able to efficiently degrade different types of
polyurethanes are reported, and their biodegradative activity was
studied by different experimental approaches. Varnish biodegradation
analyses showed that fungi were able to break down the polymer in some
of their precursors, offering the possibility that they may be recovered
and used for new polyurethane synthesis. Also, the levels of degradation
of solid polyether polyurethane foams reported in this work have never
been observed previously. Isolation of efficient polyurethane-degrading
microorganisms and delving into the mechanisms they used to degrade the
polymer provide the basis for the development of biotechnological
processes for polyurethane biodegradation and recycling.
Filiaciones:
Alvarez-Barragan, Joyce:
Univ Nacl Autonoma Mexico, Dept Bioquim, Fac Quim, Mexico City, DF, Mexico
Dominguez-Malfavon, Lilianha:
Univ Nacl Autonoma Mexico, Dept Bioquim, Fac Quim, Mexico City, DF, Mexico
Vargas-Suarez, Martin:
Univ Nacl Autonoma Mexico, Dept Bioquim, Fac Quim, Mexico City, DF, Mexico
Gonzalez-Hernandez, Ricardo:
Univ Nacl Autonoma Mexico, Dept Bioquim, Fac Quim, Mexico City, DF, Mexico
Aguilar-Osorio, Guillermo:
Univ Nacl Autonoma Mexico, Dept Alimentos & Biotecnol, Fac Quim, Mexico City, DF, Mexico
Loza-Tavera, Herminia:
Univ Nacl Autonoma Mexico, Dept Bioquim, Fac Quim, Mexico City, DF, Mexico
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