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Optimization of microbial production of lactic acid (la)

The aim is to achieve a stable fed-batch or continuous
production of la on a large scale. Emphasis will be put on
selecting strains producing l(+) la and the efficient
integration of the bioprocess with downstream processing.

The aim of the project is the research, development and optimisation of a new bioproduction process of lactic acid (herafter known as LA) for food purposes (including production of various derivatives such as ester and salts of LA), pharmaceutical and chemical industries in the CZECH REPUBLIC and ROMANIA. LA would have a great importance especially for the production of polymers and copolymers based on LA, which are important for the production of biodegradable packaging material (polylactates - see e.g. project EU 963 - DEPOSA, EUREKA News 37, p. 4 - Green Fibres). The production of LA in the CZECH REPUBLIC is intensively prepared in the company LACID A.S. which is also a partner in this project and which has gradually acquired know-how of the process from the technology proposers (ICTP and BIOTECHNIK FM). An important factor of the economy of process in addition to the engineering background is above all producing a strain of micro-organisms (from the genera Lactobacillus, Streptococcus, possibly even fungus Rhizopus). A search and selection of strains with higher productive activity (productivity, yield) and resistance to bacteriophage is one of the main topics of this project. For the laboratory and pilot plant tests, the Romanian partner proposes their culture collection of micro-organisms possessing more than 300 strains characterised morphologically and biochemically and also their experience and skill in this area of R & D. For the application in the food industry the most important form of lactic acid is its L(+) isomer which is well metabolised in the human organism. The next point in the collaboration of project partners is the optimisation of the fermentation itself, giving due consideration to optimal process control of feeding which is more complex due to the recirculation of microbial cells and the recycling of the medium removed from lactate (from the electrodialysis unit). With respect to the originality of solution based on the principal of total integration of the bioprocess with downstream processing no publications and experience on industrial scale are available. The experience of foreign companies are not published [if it exists]. The idea of application of electrodialysis for the isolation of organic acids (citric and lactic) arose in the INSTITUTE OF CHEMICAL TECHNOLOGY PRAGUE (Department of Fermentation Technology) at the beginning of 1960s but it was not launched in a scale larger than laboratory scale since there were no suitable and cheap electrodialysis membranes then available. At that time lactic acid was produced in CZECHOSLOVAKIA in three sugar factories. The production was, however, closed down because isolation and purification via the crystallisation of calcium lactate was uneconomical in contrast with citric acid. From the marketing studies of LACID A. S. it can be concluded that there is extremely high interest in lactic acid in the CZECH REPUBLIC and ROMANIA which is even expected even to increase when the polymer industry satisfactorily solves the problem of the production of biodegradable plastics on the base of lactic acid. According to our experience, the selection criteria for the successful process are the following: ? Concentration of LA in exit stream: min. 7 % wt. ? L(+) isomer of LA content in the product - at least 90% ? Productivity in the batch cultivation - min. 3 g LA/h.l ? Yield of LA from the saccharide used - at least 80 % ? Microorganisms utilised as a carbon source besides glucose and lactose above all sucrose. The requirement of high conversion to L(+) LA is not always important. In the case of production of biodegradable plastics racemic LA is sufficient. The research period is limited to 3 years with the following project objectives: 1st year: - testing and selection of strains, - fermentation media optimisation, - monitoring of important process parameters, - modelling of the process, - laboratory verification of results achieved in partner laboratories. - engineering works in the production plant, - development of fast, easy and reliable method for determination of L(+) and D(-) isomers of LA 2nd year:- development of the control strategy for the industrial scale, - set-up of the control unit, - verification of control strategies in a small scale, - analysis of results and selection of optimal variant for the process control - investigation of the changes of LA during evaporation, - modification of originally designed process in the light of new findings - large scale testing of originally designed process and modifications of unit operations. 3rd year: - large scale verification of results achieved in 1st and 2nd years, - technological innovation transfer, - evaluation of quality of LA, - analysis of the critical control points related to quality assurance, - procedures to enhance and assure the quality, - testing of LA in leather processing. Keywords: lactic acid, process integration, lactic acid bacteria.
Acronym: 
BIOLACTATE
Project ID: 
1 870
Start date: 
01-04-1998
Project Duration: 
57months
Project costs: 
930 000.00€
Technological Area: 
Market Area: 

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