Fungal Communities Associated with Degradation of Polyester Polyurethane in Soil

Abstract

Soil fungal communities involved in the biodegradation of polyester polyurethane (PU) were investigated. PU coupons were buried in two sandy loam soils with different levels of organic carbon: one was acidic (pH 5.5), and the other was more neutral (pH 6.7). After 5 months of burial, the fungal communities on the surface of the PU were compared with the native soil communities using culture-based and molecular techniques. Putative PU-degrading fungi were common in both soils, as <45% of the fungal colonies cleared the colloidal PU dispersion Impranil on solid medium. Denaturing gradient gel electrophoresis showed that fungal communities on the PU were less diverse than in the soil, and only a few species in the PU communities were detectable in the soil, indicating that only a small subset of the soil fungal communities colonized the PU. Soil type influenced the composition of the PU fungal communities. Geomyces pannorum and a Phoma sp. were the dominant species recovered by culturing from the PU buried in the acidic and neutral soils, respectively. Both fungi degraded Impranil and represented >80% of cultivable colonies from each plastic. However, PU was highly susceptible to degradation in both soils, losing up to 95% of its tensile strength. Therefore, different fungi are associated with PU degradation in different soils but the physical process is independent of soil type.The worldwide production of synthetic polymers continues to rise, resulting in an increased environmental burden through the generation of plastic waste. More than 140 million tonnes of plastic was produced worldwide in 2001 (34), and the proportion of household plastic waste in the average American home increased from 3 to 5% of total waste in 1969 (15) to more than 30% in 1995 (21) and continues to rise. Many plastics are both physically and chemically robust and cause waste management problems (10). However, several families of plastics undergo biodegradation in the environment, and an understanding of how this degradation occurs may aid in the development of strategies to exploit these processes for waste management purposes.Microorganisms are responsible for the majority of plastic degradation (6), and abiotic factors such as photodegradation or hydrolysis play a very minor role (18,42). Plastics vulnerable to biodegradation include the polyhydroxyalkanoates, polycaprolactone, polylactic acid, polyvinyl chloride (31, 32), and polyester polyurethane (PU). PU is used in a variety of industrial applications, including insulating foams, fibers, and synthetic leather and rubber goods. The presence of ester and urethane linkages in the backbone of PUs makes them susceptible to hydrolysis by enzymes secreted by microorganisms, releasing breakdown products which may act as a carbon source and lead to a weakening of the tensile strength (1,13,22,26,27).Both PU-degrading fungi (5,6,12,32) and bacteria (1, 20, 23) have been isolated from PU, indicating that there are potential reservoirs of PU-degrading organisms widespread in the environment. It...

Polycarbonate biodegradation by isolated molds using clear-zone and atomic force microscopic methods

“…With the growth of global population and advances in technology, the worldwide use of plastic materials has increased, causing many waste management problems (Cosgrove et al 2007;Tokiwa et al 2009). A considerable attention has been devoted to the biodegradability of polymeric materials mainly because of the environmental pollution by waste polymers.…”

“…Suyama et al (1998) and Pranamuda et al (1999) isolated poly(hexamethylene carbonate)-and poly(butylene carbonate)-degrading microorganisms that were phylogenetically diverse (Pranamuda et al 1999;Suyama et al 1998). Cosgrove et al (2007) investigated the fungal communities associated with degradation of polyester polyurethane (PU) in soil and reported that different fungi can degrade PU in different soils (Cosgrove et al 2007). Also, the degradation of poly-3-hydroxy-butyric acid (PHB) by fungi isolated from various environments was detected by clear-zone method, and fungi such as Aspergillus and Penicillium showed PHB degradation activity (Lee et al 2005).…”

“…Fungi may be involved in the primary degradation of polymers due to their dominant ability to compose organic matter (Lee et al 2005) and also can generally exceed the bacterial biomass (Kim and Rhee 2003). There are many reports on bacterial degradation of polymers; however, the reports on fungal degradation are relatively rare (Cosgrove et al 2007). The present study aimed to investigate the biodegradation activity of molds isolated from soil and waste leachate on polycarbonate polymers in an in vitro condition.…”

Biodegradation of Synthetic Plastics

“…[ 16] Geomyces pannorum Nectria gliocladioides Penicillium ochrochloron [17] Bacillus subtilis [20] Pseudomonas chlororaphis [21] Alicycliphilus spp. [19] Polyethylene Brevibacillus borstelensis [36] Rhodococcus rubber [37] Penicillium simplicissimum YK [9] Brevibacillus borstelen [38] Penicillium frequentans Bacillus mycoides [10] Aspergillus niger Penicillium pinophilium [11] Penicillium pinophilium Aspergillus niger Cliocladium virens Penicillium chrysosporium [12] Bacillus sphericus Bacillus cereus [13] Streptomyces spp.…”

Biodegradation of Polylactide Modified with Starch by Selected Species of Molds

“…Although there were many experiments conducted with use of bacteria to degrade plastics [12], the molds effect on unmodified and starch modified PLA is still relatively uninvestigated field [13]. In this study the biodegradation by two mold species of unmodified and starch-modified with two different starch concentrations (20% and 50%) PLA was tested.…”