Microbial degradation of natural and of new synthetic polymers

Abstract

In landfills, deposited waste material is usually faced with strictly anoxic conditions. This means that the design of new biodegradable polymers must take into consideration that degradation should be possible especially in the absence of molecular oxygen. Poly‐β‐hydroxybutyrate is depolymerized by the anaerobic fermenting bacterium Ilyobacter delafieldii through an extracellular hydrolase. Monomers are degraded inside the cells through classical β‐oxidation. Polyalkanoates containing odd‐numbered or branched‐chain acid monomers should he degraded in an analogous manner; in most cases the final mineralization of these residues requires special pathways. A comparison of the chemistry of natural polymer biodegration leads to the conclusion that synthetic biodegradable polymers should be designed in the future to contain linkages which can be cleaved by extracellular hydrolytic enzymes. Recent findings on aerobic and anaerobic bacterial degradation of synthetic polyethers suggest that natural evolution of new depolymerizing enzymes, perhaps from existing hydrolases, could be possible in a reasonable amount of time, provided that the monomers are likely energy sources for a broad variety of microbes.

Polymers as Solid Waste in Municipal Landfills

“…30 Laboratory studies have shown that polyhydroxybutyrate (PHB) can be biodegraded by either aerobic or anaerobic conditions. 31 The tendency for PCL and PHB to biodegrade under active aerobic conditions is consistent with results from field soil burial tests, 32 suggesting that PCL and PHB polymers will degrade in the relatively few landfills that are managed for active biodegradation. Other polyesters are alkyd resins for paints, which are formed by condensation of polyhydric alcohols with mono-or polybasic acids.…”

Recent Advances in Biodegradable and Biocompatible Synthetic Polymers Used in Skin Wound Healing

“…Natural polymeric biomaterials include polypeptides (such as collagen, gelatin, and silk fibroin (SF)), polysaccharides (such as sodium alginate (SA), chitosan (CS), cellulose, and hyaluronic acid (HA) derivatives), and so on [8]. These materials are derived from biological sources which possess excellent biocompatibility and can be degraded by enzymes [9]. Beyond that, their specific molecular structures can assist in wound healing.…”

Exploitation of microbial activities at low pH to enhance planetary health

“…Even highly polluting fossil-based polymers, which are not biodegradable in reasonable time, could be degraded, under the specific conditions, by Aspergillus spp., Pseudomonas spp., Brevibacillus spp., Mucor spp., and so on (Ru et al 2020 ). A circular design concept, that involves the design of new polymers based on the knowledge on metabolic capabilities of micro-organisms and suitability of specific bonds for microbial cleavage in order to enable degradation and resource recovery (Schink et al 1992 ), could indeed play an important role for really circular and sustainable solutions in the future.…”