Deterioration of expanded polystyrene caused by Aureobasidium pullulans var. melanogenum

CASTIGLIA VALERIA; KUHAR FRANCISCO

REVISTA ARGENTINA DE MICROBIOLOGíA

ASOCIACION ARGENTINA MICROBIOLOGIA

Lugar: Buenos Aires; Año: 2015

0325-7541

An expanded-polystyrene factory located in northern Buenos Aires reported unusual dark spots causing aesthetic damage in their production. A fungal strain forming black-olive colonies on extract malt agar medium was isolated from the damaged material and identified as Aureobasidium pullullans var. melanogenum. This fungus is particularly known for its capacity to produce hydrolytic enzymes and a biodegradable extracellular polysaccharide known as pullulan, which is used in the manufacture of packaging material for food and medicine. Laboratory tests were conducted to characterize its growth parameters. It was found that the organism was resistant to a wide range of pHs but did not survive at temperatures over 65 °C. The proposed action plan includes drying of the material prior to packaging and disinfection of the machinery used in the manufacturing process and the silos used to storage the raw material.