Biochemical and Biotechnology
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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
