Development of Integrated Process for Microbial Bioplastic Production from Plant Biomass

This review touches on recent trials for producing microbial polyhydroxyalkanoates (PHAs), which are used as a bio-based plastic, from renewable and non-edible lignocellulosic biomass. Lignocellulose is composed of cellulose, hemicellulose and lignin, which form a persistent complex. Thus, for the efficient saccharification of lignocellulose, the physical/chemical processes for removing lignin and unstiffening cellulose fibers are required. The obtained sugar is typically a mixture of glucose and xylose, and contains a certain inpurity derived from lignocellulose and/or byproduct generated during pretreatment and subsequent saccharification processes. The microbes used for PHA production need to utilize the mixed sugar and to be resistant to the impurities. This review introduces several examples for addressing this issue. Moreover, an important direction is to design the polymer with better properties. Metabolic and enzyme engineering are powerful tools to biosynthesize various useful polymers from non-related sugar carbon sources. In particular, microbial production of lactate-based polymer from xylose is a potent platform. (C) 2013, The Society of Polymer Science, Japan