Isotactic polypropylene biodegradation by a microbial community: physicochemical characterization of metabolites produced.

From a selective enrichment culture prepared with different soil samples on starch-containing polyethylene we isolated four microaerophilic microbial communities able to grow on this kind of plastic with no additional carbon source. One consortium, designated community 3S, was tested with pure isotactic polypropylene to determine whether the consortium was able to degrade this polymer. Polypropylene strips were incubated for 5 months in a mineral medium containing sodium lactate and glucose in screw-cap bottles. Dichloromethane crude extracts of the cultures revealed that the weight of extracted materials increased with incubation time, while the polypropylene sample weight decreased. The extracted materials were characterized by performing chromatographic and spectral analyses (thin-layer chromatography, liquid chromatography, gas chromatography-mass spectrometry, infrared spectrometry, nuclear magnetic resonance). Three main fractions were detected and analyzed; a mixture of hydrocarbons at different degrees of functionalization was found together with a mixture of aromatic esters, as the plasticizers usually added to polyolefinic structures.