Nutritional and environmental factors in ethanol fermentation by Saccharomyces cerevisiae
Using Saccharomyces cerevisiae as a model system, a basic study of the nutritional and environmental factors in ethanol fermentation was carried out to provide fundamental and practical bases for design of fermentation media and culture conditions. The requirements for all active medium components need to be determined in order to establish balanced media, which are important to reduce raw materials costs and to minimize inhibition from build-up of excess feed components in recycle processes with selective ethanol removal. The effect of feed concentration of individual nutrients was determined and allowed formulation of media optimal with respect to the major fermentation parameters. Biotin, pantothenate, myoinositol, potassium, and phosphates appeared to stimulate growth preferentially to ethanol production. Thiamine and pyridoxine appeared to have the opposite effect. A conceptual model was proposed to relate the effects of these nutrients to biochemical pathways and functions. The minimum cost combination of raw materials to achieve a medium of well defined components can be determined with a linear program. The effect of dissolved oxygen was studied from essentially zero to 346 mm Hg oxygen tension, showing a continuous decline in specific ethanol productivity with increasing oxygen over this range. Long term continuous cultures resulted in decreased media requirements for growth factors and increased tolerance for ethanol inhibition, most probably through adaptation. An ethanol productivity of 5.6 g/l-hr in continuous culture was achieved with a completely synthetic medium with the improved culture.
- OSTI ID:
- 5950283
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ETHANOL
BIOSYNTHESIS
FERMENTATION
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MODELS
BIOTIN
CONTINUOUS CULTURE
INHIBITION
OPTIMIZATION
OXYGEN
PHOSPHATES
POTASSIUM
PYRIDOXINE
QUANTITY RATIO
RAW MATERIALS
SACCHAROMYCES CEREVISIAE
SUBSTRATES
THIAMINE
ALCOHOLS
ALKALI METALS
AMINES
AZINES
AZOLES
BIOCONVERSION
CARBOXYLIC ACIDS
ELEMENTS
FUNGI
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IMIDAZOLES
KINETICS
MATERIALS
METALS
MICROORGANISMS
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PLANTS
PYRIDINES
PYRIMIDINES
REACTION KINETICS
SACCHAROMYCES
SYNTHESIS
THIAZOLES
VITAMIN B GROUP
VITAMINS
YEASTS
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