Bio-synthesis of poly(lactic acid) by wild type PHA-producing bacteria

2013 Fiscal Year Final Research Report

• Project/Area Number: 23655145
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Environmental chemistry
• Research Institution: Kyoto Institute of Technology
• Principal Investigator: AOKI Takashi 京都工芸繊維大学, 工芸科学研究科, 准教授 (80231760)
• Project Period (FY): 2011 – 2013
• Keywords: バイオベースポリマー / 生体材料 / 生分解性・生体吸収性 / 応用微生物 / バイオテクノロジー

Research Abstract

Poly(lactic acid) (PLA) is one of bio-based polymers synthesized from renewable resources in plants. We have recently found that PLA oligomers existed in a microbial cultured system of Ralstonia eutropha (R. eutropha), which is known to form other aliphatic polyester, poly(3-hydroxybutyrate) within its body. This research aimed to find optimal cell-culture conditions for both better mass production and higher molecular weight of PLA, establishing the suitable accumulation manner of the polyester under mild conditions. PLA obtained from R. eutropha culture system was found to composed of D-formed lactic acid repeating units, while that from other strain cell, Bacillus megaterium, contained D- and L-formed ones. The optical purity of lactic acid units in PLA depended on the cell strains. It was also found that our cell conditions could not result in large mass production or high molecular weight of PLA. Even now, we are trying to find out the optimal cell-culture conditions.