Optimisation of bioproductivity by engineering the response of yeast to starvation

• Research unit: EU RFP
• Project number: 98.0239

Key words (English)

Biotechnology; yeast physiology; bioprocess optimisation

Alternative project number (English)

EU project number: BIO4CT980562

Research programs (English)

EU-programme: 4. Frame Research Programme - 4.1 Biotechnology

Short description (English)

See abstract

Further information (English)

Full name of research-institution/enterprise:
EPF Lausanne
Laboratoire de Génie Chimique et Biologique
DC - IGC

Partners and International Organizations (English)

Coordinator:University of Göteborg (S)

Abstract (English)

The general aim of the EU project was to understand and engineer the starvation response in yeast in order to improve bioproductivity in aerobic and anaerobic industrial processes. Thus a key parameter is the fermentative capacity of the yeast for the baking industry. This capacity is defined by the type of yeast used, the conditions under which the yeast was grown and stored prior to use in baking. The fermentation capacity is the ability of the stored yeast to initiate carbon dioxide production and the rate at which this gas is produced upon combining with baking ingredients.
The aim of the project was to examine a range of wild- type and genetically modified yeast strains and determine the optimum conditions for growth, particularly the culture conditions responsible for affecting subsequent fermentation activity. Of these conditions the most important are the availability of carbon and nitrogen sources in the culture medium and which of these becomes growth limiting. In addition the ability to ferment or respire different substrates and the ability of the yeast to transport these substrates into the cell. Finally the ability of the yeast strains to lay down storage compounds in the cell, provoked by nutrient limitations, is important for the successful storage of the yeast and subsequent fermentative activity. In many cases a decline in the fermentation capacity has been observed and it is important to understand why such that novel strains can be constructed and/or the industrial process controlled in order to reproducibly maintain a defined fermentation capacity during industrial fermentation processes, particularly related to baking.
The work content was planned in 5 work packages (WP): WP1. Control of sugar transport during starvation; WP2. Control of nitrogen transport during starvation; WP3. Control of glycolytic capacity during starvation; WP4. Trehalose and glycogen levels during starvation; WP5. Control by intracellular signalling during the starvation response
Our role/contribution was defined as the physiological characterisation in high performance bioreactors of wild type strains and strains engineered in their hexose transport and glycolytic systems, with special emphasis on the accumulation of storage carbohydrates. Although the work done was planned under WP1 and WP3, it is finally presented under WP1 and 4. However, the data being very general can be used by members of all work packages. The results have been extremely promising, and have included the development of on- line monitoring methods for the continuous measurement of many yeast metabolites, which has facilitated detailed physiological studies of the different yeast strains. These methods, culture conditions metabolic flux models have been made available to all participants (both academic and industrial) to facilitate yeast strain development and optimisation of fermentative capacity.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 98.0239