Production and applications of polylactic acid

Polylactic acid (PLA) is a biodegradable polymer made up of lactic acid monomers. It is being increasingly produced today because of its potential applications in textile industry, pharmaceutical, packaging, bioremediation, and many more. The commercial production of lactic acid enantiomers is mostly done using renewable materials such as lignocellulosic and starchy biomass along with the milk-processing industry by-products like whey. Homofermentative and heterofermentative lactic acid bacteria (LAB) are most widely used for production. However, some cyanobacteria, fungi, and yeast have also been reported for efficient lactic acid fermentation. Genetic engineering and molecular biology approaches are being continuously used for strain improvement for more efficient and economic production. Fermentation has been commercially performed in batch, fed-batch, and continuous mode with the use of techniques like membrane filtration, reactive extraction, and others for separation from the broth. PLA can be composed of either pure l-isomer or d-isomer or both d, l-lactic acid depending upon the requirement and use. Polymerization processes such as polycondensation, ring-opening polymerization, and direct methods like azeotropic dehydration and enzymatic polymerization are used to form PLA from lactic acid monomers. This paper discusses the need of PLA and the methods used for its commercial production along with its structural properties and wide range applications.