Production of Pure L(+) Lactic Acid

Introduction

Lactic acid is the smallest chemical molecule with an asymmetric carbon and therefore exists in two optically active isomeric forms, the L(+) and (D-). Optically pure lactic acid is important for the production of polylactide because the physical properties of the polylactide are dependent on the stereo chemistry of the individual lactic acid molecule. Microbial source is the only source of producing optically pure lactic acid isomers. In microbial processes, lactic acid is formed via reduction of pyruvate via lactate dehydrogenases (LDH), for the regeneration of NAD+. Some lactic acid bacteria, produce both L(+) and D(-) lactate by distinct and stereo specific enzymes called L-LDH and D-LDH respectively. However, the ratios of L(+) and D(-) lactate secreted into the culture supernatent changes with growth stage and conditions. The examples of such species are L. helveticus, L. delbruecki, L. bulgaricus, L. plantarum, L. lactis etc. the species like Lactobacillus casei subspecies rhamnosus produces solely L(+) lactic acid. In the present work, we will use this species of Lactobacillus. Optically pure L(+) lactic acid microbial production is an attractive process. Optically pure L(+) lactate is used to prepare polylactide which has application in medical industries. Because, lactate can be easily converted to strong , highly transparent and readily biodegradable polyesters, it is emerging as a potential material for environment friendly plastic. Due to strict directives of WHO, the polylactide prepared from L(+) lactate can only be used for medical purposes as the other forms remain unutilized in body, causes irritation and acidity. Similarly pharmaceutical and food industries also prefer only L(+) lactate which can be metabolized by human bodies. Optically pure lactate preparation is possible - by using homofermentative Lactobacillii (producing both isomeric forms) by using heterofermentative Lactobacillii (produce specifically L(+) form of lactate along with other products), in anaerobic fermentation. In both options, Lactobacillus strains have to be modified to maximize pure L(+) lactate production. Many efforts have been directed for previous type of strains but could not produce highly effective results. In our studies we are trying to use the latter strategy.

Special Features:

Processes and products may be used for industrial uses.

Prospective Users:

Industry people

Keywords:

Bioproduction, lactic acid

Type of Technology:

Process and product

Contact for more information

The Director
Foundation for Innovation and Technology Transfer
Indian Institute of Technology Delhi
Hauz Khas, New Delhi-110016
Tel : 91-011-26597167, 26857762, 26581013
Fax : 91-011-26851169
E-mail : mdfitt@gmail.com