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°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.
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Kim et al. (2008) studied this question.