Degradation of poly(ethylene succinate) by mesophilic bacteria

Abstract

We report for the first time the mesophilic poly(ethylene succinate)(PESu)-degrading microorganisms isolated from aquatic and soil environments. The degrading isolates were classified into two groups, Gram-positive bacterium and fungus. Phylogenetic analysis revealed that the degrading bacteria belong to the genera Bacillus and Paenibacillus. Thus, PESu may be degraded by very limited species in natural environments. Furthermore, strain KT 1012 which could degrade PESu film at the fastest rate among the degrading bacteria in this study was characterized in detail. The DNA G+C content was 40.4 mol% and iso-C15:0 was the major fatty acid. The temperature optima for growth was approximately 40–45 °C. The phenotypic properties and the phylogenetic inference indicate that strain KT1012 is a related species to Bacillus pumilus. Strain KT1012 did not hydrolyze poly(lactic acid), poly(butylene succinate), poly(3-hydoroxybutyrate) but hydrolyzed PESu, poly( ϵ-caprolactone) films and olive oil. Strain KT1012 exhibited a high PESu hydrolytic activity in liquid culture when it was cultivated on a nutrient rich medium such as LB medium, suggesting that the hydrolytic activity is not expressed inducibly but constitutively in strain KT1012.