Microbial degradation of polyester polyurethane

Abstract

During the course of these studies, polyester polyurethane foam has been found to be readily degraded in soil and marine environments. The incorporation of the formulation biocide Vinyzene E.P. reduced the rate and extent of degradation in test material exposed to soil conditions, but was found to be ineffective in preventing degradation when exposed to the marine environment.
As a result of these studies, a number of fungi, representing a range of genera, have been isolated, identified, and shown using Kochian principles to degrade polyester polyurethane as a sole source of carbon. A list of isolates is submitted. In addition, a number of bacteria, hitherto unreported as deteriogens of polyester polyurethane, have been isolated and also shown, again using Kochian principles, to degrade polyester polyurethane. In order to effect degradation, the bacteria were found to require supplementation of the basal mineral salts medium with non-defined, complex sources of organic nitrogen, such as yeast extract.
Chemical analysis of degraded test material, using FT-IR spectroscopy has provided evidence to suggest that the ester linkage of the polymer was hydrolysed during degradation by a bacterial isolate studied, resulting in marked reductions
in the physical properties recorded. No degradation, either in terms of chemical composition or in the physical properties of the polymer was recorded where the test material was inoculated with this isolate in a mineral salts medium supplemented with glucose, suggesting that the enzymes involved in the degradation process were catabolically suppressed and therefore inducible.
Extracellular esterase enzyme activity was detected in cellfree supernatants where the mineral salts medium was supplemented with yeast extract, but not in the case where glucose was used. However the addition of the test material
did not enhance the level of esterase activity detected.
Purification/concentration of these enzymes and characterisation studies using gel filtration chromatography, SDS-PAGE and PAGE were found to support these findings. The results of the present studies suggest that the test material was degraded by the bacterial isolate as a result of co-metabolism.