Fungal Biodegradation of Polyurethanes

Abstract

Polyurethanes (PURs) are versatile polymers used in a wide variety of fields, such as the medical, automotive, textile, thermal insulation, and coating industries as well as many everyday objects. Many PURs have applications that require a long service life, sometimes with exposure to aggressive conditions. They can undergo different types of physicochemical and biological degradation, but they are not compostable, and many of them constitute persistent waste in the environment. Although both bacteria and fungi can be involved in the degradation of PURs, fungi are often the main biodegradation agents. The chemical structure of PURs determines their degree of biodegradation. Fungal biodegradation of PURs is linked to the production of enzymes, mainly esterases and proteases, alongside laccases, peroxidases, and tyrosinases, which can modify the structure of polyurethane compounds by forming carbonyl groups. The experimental analysis of the biodegradation of PUR can be carried out by bringing the polymer into contact with a mold in pure culture or with a microbial consortium. Then, global measurements can be taken, such as weight loss, tensile tests, or the ability of microorganisms to grow in the presence of PUR as the sole carbon source. The analysis of the chemical structure of the polymer and its degradation products after fungal growth can confirm biodegradation and specify the mechanism. The main avenues of future research are directed towards the development of fully biodegradable PURs and, on the contrary, towards the development of PURs that are more resistant to degradation phenomena, in particular biodegradation, for applications where the material is in contact with living organisms.

A New Strategy for the Treatment of Old Corrugated Container Pulping Wastewater by the Ozone-Catalyzed Polyurethane Sponge Biodegradation Process

“…The diversity of microbial communities also decreased to different degrees after the treatment of OCC pulping wastewater. In addition, the Shannon index of fungi remained relatively stable, which may be due to the presence of dominant fungal species and the fact that certain fungi can maintain their growth level by degrading polyurethane sponges [21].…”

“…The diversity of microbial communities also decreased to different degrees after the treatment OCC pulping wastewater. In addition, the Shannon index of fungi remained relatively stable, which may be due to the presence of dominant fungal species and the fact that certain fungi can maintain their growth level by degrading polyurethane sponges [21]. To further investigate the functional fungal species in the mixed microbial community, Figure 9a shows the changes in fungal genus-level diversity in three different samples of biofilms.…”

Surface Properties of a Biocompatible Thermoplastic Polyurethane and Its Anti-Adhesive Effect against E. coli and S. aureus

“…A very versatile biomaterial used in medical applications such as catheters, wound dressings, coatings, and drug delivery systems is represented by polyurethane (PU) [23][24][25][26], in particular by thermoplastic PU (TPU). This polymer is composed of soft and hard segments, polyols and isocyanates, respectively [24,26], whose proportions determine a different degree of flexibility, toughness, and softness [23] and confer good mechanical properties. In addition, TPUs have been shown to be durable, biocompatible, biostable [27], and hemocompatible [28][29][30], making them suitable for biomedical applications.…”