STUDY OF BIOFOULING OF POLYHYDROXYALKANOATE (PHA) FILMS IN WATER BY SCANNING ELECTRON-MICROSCOPY

This study was carried out to evaluate the degradation by microorganisms in marine and freshwater environments, of polyhydroxyalkanoate (PHA) films made from extracts of halobacteria. Scanning electron microscopy observations showed that PHA films, both in sea- and freshwater, were rapidly colonised by bacteria and microalgae, including several species of diatoms. Very few hyphae were seen on the films even after 30 days or more in water. This contrasts with previous studies of PHA degradation in soil (Lopez-Llorca et al., 1992) where fungal hyphae were far more numerous. Signs of decomposition such as etched areas associated with bacteria were found after the immersion of the PHA films, but hyphal tracks were not as common as in PHA samples buried in soil. Microalgae, although frequently observed, appeared to use the PHA film as growth support rather than degrading it. The degradation of the films in an aquatic medium, measured by weight loss, was faster than in the soil.