A new strain exhibiting poly(L-lactic acid) (PLLA)-degrading activity was isolated from the compost loaded with low-molecular weight PLLA. The strain was rod-shaped gram positive bacterium and was identified to be Bacillus licheniformis by the 16S rDNA sequence analysis. It degraded not only low-molecular weight PLLA but also other PLLAs having higher molecular weight. The lower the molecular weight of PLLA, the faster the biodegradation rate. And thereby 45% and 81% of PLLAs with weight average molecular weight of 256,000 and 5,000, respectively, were metabolized into CO2 after 40 days of biodegradation at 58 degrees C in the sterilized compost inoculated with the bacterium. According to the 16S rDNA sequence analysis, B. licheniformis PLLA-2 belonged to Bacillus spp. phylogenetically. However, there existed almost no phylogenetic relationship between B. licheniformis PLLA-2 and the previously reported PLLA-degrading strains. (C) 2008 Wiley Periodicals, Inc.