ORIGINAL PAPER Degradation of polyester polyurethane by a newly isolated soil bacterium, Bacillus subtilis strain MZA-75 Ziaullah Shah • Lee Krumholz • Deniz Fulya Aktas • Fariha Hasan • Mutiullah Khattak • Aamer Ali Shah Received: 8 December 2012 / Accepted: 18 March 2013 / Published online: 28 March 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract A polyurethane (PU) degrading bacterial strain MZA-75 was isolated from soil through enrich- ment technique. The bacterium was identified through 16S rRNA gene sequencing, the phylogenetic analysis indicated the strain MZA-75 belonged to genus Bacillus having maximum similarity with Bacillus subtilis strain JBE0016. The degradation of PU films by strain MZA-75 in mineral salt medium (MSM) was analyzed by scanning electron microscopy (SEM), fourier transform infra-red spectroscopy (FT-IR) and gel permeation chromatography (GPC). SEM revealed the appearance of widespread cracks on the surface. FTIR spectrum showed decrease in ester functional group. Increase in polydispersity index was observed in GPC, which indicates chain scission as a result of microbial treatment. CO 2 evolution and cell growth increased when PU was used as carbon source in MSM in Sturm test. Increase in both cell associated and extracellular esterases was observed in the presence of PU indicated by p-Nitrophenyl acetate (pNPA) hydrolysis assay. Analysis of cell free supernatant by gas chromatography–mass spectrometry (GC–MS) revealed that 1,4-butanediol and adipic acid mono- mers were produced. Bacillus subtilis strain MZA-75 can degrade the soft segment of polyester polyure- thane, unfortunately no information about the fate of hard segment could be obtained. Growth of strain MZA-75 in the presence of these metabolites indicated mineralization of ester hydrolysis products into CO 2 and H 2 O. Keywords Polyester polyurethane Á Biodegradation Á Bacillus subtilis Á Scanning electron microscopy Á Fourier transform infra-red spectroscopy Á Gas chromatography–mass spectrometry Introduction Polyurethane (PU) is the condensation product of polyisocyanate and polyol having intra-molecular urethane bonds (carbonate ester bond, –NHCOO–). It is a diverse group of synthetic polymers, commonly utilized as a constituent material in many industries including furniture, coating, construction materials, fibers, and paints (Sauders and Frisch 1964). Since PU is such a versatile polymer, its production continues to rise worldwide. The global market for PU was estimated at 13,650.00 kilo tons in 2010 which is expected to reach 17,946.20 kilo tons by 2016, growing at a compound annual growth rate (CAGR) Z. Shah Á F. Hasan Á M. Khattak Á A. A. Shah (&) Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan e-mail: alishah@qau.edu.pk; alishah_75@yahoo.com L. Krumholz Á D. F. Aktas Department of Microbiology and Plant Biology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, USA 123 Biodegradation (2013) 24:865–877 DOI 10.1007/s10532-013-9634-5