Biosynthesis, Properties, and Biodegradation of Lactate-Based Polymers

Abstract

Tel/Fax: +81-11-706-6610.The tight crude oil supply and its negative impacts on the environment have accelerated efforts towards the search for alternatives to the conventional petrochemical-derived plastics. Polylactic acid (PLA), a polymer produced from renewable resources has emerged as a potential substitute to the conventional synthetic petrochemical-derived plastics owing to their biodegradable and bioresorbable nature. Despite these advantages, PLA has had little success as a substitute to the conventional petrochemical-derived plastics because the PLA synthesis; a two-step bio-chemo process where fermentative lactic acid is polymerized using heavy metal catalysts is expensive. Furthermore, the heavy metal catalyst remnants in the polymer hinder the use of PLA for medical devices and food handling packages. To overcome these obstacles, bacteria have been genetically manipulated to synthesize lactate (LA)-based polymers in a single-step metal-free system. This chapter reviews the production of LA-based polymers using a lactate-polymerizing enzyme (LPE). Production of LA-enriched and PLA-like polymers in bacteria from glucose and xylose, metabolic/ genetic engineering for polymer yield enhancement, polymer properties, and the biodegradability of the LA-based polymers will be discussed. Moreover, future perspectives on the synthesis and applications of the LA-based polymers will be mentioned.

Green Polymer Chemistry: Some Recent Developments and Examples

“…Nduko et al (38) reviewed the production of lactic acid (LA)-based polymers via a one-step metal-free system, using a lactate-polymerizing enzyme. Included in their chapter were the production of LA-enriched and PLA-like polymers in bacteria from glucose and xylose, metabolic/genetic engineering for polymer yield enhancement, and studies of the properties and the biodegradability of the LAbased polymers.…”

“…Carbohydrate feedstock was engaged for the production of PLA (38)(39)(40)48), poly(2,5-dihydro-1,4-dioxane) (49), modified cellulose (50), and phosphorus -containing isosorbide esters (51).…”

“…The preparation of the dimer acid-epoxide adhesive by Li and Li (55) appears not to involve organic solvents or toxic chemicals and is more environmentally friendly. Furthermore, the use of single-step metal-free system for the synthesis of PLA (38) has the potential of being a more eco-friendly process.…”

“…Several chapters in this book deal with PLA (38)(39)(40)48). Enzymes and enzyme-based conjugates were proposed to be useful products for the treatment of wastewater (35).…”

Studies on electrospun poly (lactic acid) fibers and low density poly (ethylene) / thermoplastic starch blends as food packaging materials

“…Below are several studies on using electrospun fibers in food packaging materials, however these have not been materialised commercially. PLA is gaining popularity in food packaging industry as a bio-based and environment friendly material [92][93][94][95][96][97][98] .…”