Fungal colonization and biodeterioration of plasticized polyvinyl chloride

Significant substratum damage can occur when plasticized PVC (pPVC) is colo nized by microorganisms. We investigated microbial colonization of pPVC in an in situ, longitudinal study. Pieces of pPVC containing the plasticizers dioctyl phthalate and dioctyl adipate (DOA) were exposed to the atmosphere for up to 2 years, Fungal and bacterial populations were quantified, and co lonizing fungi were identified by rRNA gene sequencing and morphological ch aracteristics. Aureobasidium pullulans,vas the principal colonizing fungus, establishing itself on the pPVC between 25 and 40 weeks of exposure, A gro up of yeasts and yeast-like fungi, including Rhodotorula aurantiaca and Klu yveromyces spp,, established themselves on the pPVC much later (after 80 we eks of exposure), Numerically, these organisms dominated A, pullulans after 95 weeks, with a mean viable count +/- standard error of 1,000 +/- 200 yea st CFU cm(-2), compared to 390 +/- 50 A, pullulans CEU cm(-2). No bacterial colonization was observed. We also used in vitro tests to characterize the deteriogenic properties of fungi isolated from the pPVC. All strains of A. pullulans tested could grow with the intact pPVC formulation as the sole s ource of carbon, degrade the plasticizer DOG produce extracellular esterase , and cause weight loss of the substratum during growth in vitro, In contra st, several yeast isolates could not grow on pPVC or degrade DOA. These res ults suggest that microbial succession may occur during the colonization of pPVC and that A, pullulans is critical to the establishment of a microbial community on pPVC.