Keywords :
Degradation,
Lipase,
Streptomyces sp.,
Solvent tolerant,
Re-polymerization,
Poly lactic acid
บทคัดย่อ :
Poly (lactic acid) (PLA) is a biodegradable plastic that has received considerable attention since it plays an
important role in replacing commercial plastics and resolving the global warming problem. Recently, biological
degradation and polymerization studies of PLA have been an active topic. Microbial solvent-tolerant and ther-
mostable lipases are interesting since they have the potential to induce PLA polymerization. The aims of this
study are to isolate solvent-tolerant and thermostable lipase-producing actinomycetes and to apply the crude
enzyme produced by an isolated strain for PLA polymerization. According to the results, the best solvent-tolerant
and thermostable lipase-producing actinomycete was strain A3301, with a lipase activity of 108 U/ml in the
production medium. The crude enzyme produced by strain A3301 demonstrated the optimum temperature and
thermostability at 60 ?C and 45-55 ?C, respectively. Moreover, the enzyme showed the ability to tolerate
10-20% (v/v) hexane and toluene. Strain A3301 was identified as Streptomyces sp. by using the 16S rDNA
sequence. A thermo-solvent-tolerant lipase from this strain was used in PLA polymerization experiments. The
optimal conditions for PLA synthesis were 60 ?C for 8 h, using dried lipase at a concentration of 10% (w/v) and a
fixed lactic acid concentration of 450 g/L under a nitrogen atmosphere. The highest molecular weight of the PLA
product was 525 Da, and the degree of polymerization was approximately 7. Subsequently, the repolymerization
process of PLA using this enzyme was investigated. The maximum molecular weight of the PLA product was 577
Da, and the degree of polymerization was approximately 8.
เอกสารอ้างอิง :
Panyachanakul, T., Lomthong, T., Lorliam, W., Prajanbarn, J., Tokuyama, S., Kitpreechavanich, V., & Krajangsang, S. (2020). New insight into thermo-solvent tolerant lipase produced by Streptomyces sp. A3301 for re-polymerization of poly (DL-lactic acid). Polymer, 204, 122812.
