Isolation of a thermophile degrading poly(butylene succinate-co-butylene adipate)

A thermophile, strain 73, which degrades poly(butylene succinate-co-butylene adipate) (PBSA) film was isolated from 95 soil samples obtained from different locations by cultivation using an enrichment culture technique at 60 degrees C. At this temperature, the strain grew on PBSA and the dissolved total organic carbon (TOC) concentration in the medium changed according to the growth stage, i.e., after the TOC concentration rapidly reached the minimum, it increased rapidly until it reached a peak and then decreased thereafter. During cultivation, PBSA was almost eliminated and the solution viscosity of the residual PBSA decreased markedly. Gel permeation chromatograms of the residual PBSA showed a significant decrease in the main peak and the appearance of a new peak at the low molecular weight region. The strain was identified as Bacillus stearothermophilus, which has an optimum growth temperature of approximately 63 degrees C.