Sun-Hee Lee and Mal-Nam Kim
Department of Biology, Sangmyung University, 7 Hongji-dong, Chongro-gu, Seoul 110-743, South Korea.
Two bacteria, Burkholderia cepacia PBSA-1 and Pseudomonas aeruginosa PBSA-2, capable of degrading poly(butylene succinate-co-butylene adipate) (PBSA) were isolated from activated sludge soil and cultivating soil in Korea by using the enrichment culture and the clear zone test at 27 °C and 37 °C. In this study, two bacteria showed a very high activity for PBSA degradation so that 78% of PBSA with an initial concentration of 0.01% was mineralized into CO2 during 40 days of the modified Sturm test. To analyze the PBSA-degrading enzyme encoding gene, lip A, PCR, cloning and sequencing were performed on the PBSA-degrading strains. The lip A appeared at about 1.5 kb. The amino acid sequences possessed the lipase box, Gly-His-Ser-Gln-Gly and sequences of the two strains received their accession number of EF189714 and EF189715, respectively, from GenBank. The lip A showed 87.9% homology between those of B. cepacia PBSA-1 and P. aeruginosa PBSA-2. Also they showed 83.2–86.9% and 85.9–89.7% homology compared with the Pseudomonas lipase subfamily, respectively. However, the genes of B. cepacia PBSA-1 and P. aeruginosa PBSA-2 exhibited no more than 22.9–26.9% and 21.3–23.5% of homology, respectively, when compared with the previously reported bioplastics-degrading enzyme encoding genes. Consequently, the PBSA-degrading enzyme lipase gene, lip A, was presumed to be a characteristic gene distinct from other bioplastics-degrading enzyme encoding genes.