1
Biological Systems Engineering Group, BIOSE, Biochemical Engineering Department, Federal University of Rio de
Janeiro, Av. Horácio Macedo, 2030, CT, E,203, Cidade Universitária, 21941,909, Rio de Janeiro, Brazil
2
IBB,Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710,057, Braga, Portugal
is one of the most extensively studied ‘‘non,conventional’’ yeasts, being a strictly aerobic
microorganism capable of producing important metabolites and having an intense secretory activity, which justifies efforts
to use it in industry (as a biocatalyst), in molecular biology and in genetics studies. Moreover, has been
considered an adequate model for dimorphism studies in yeasts. presents the ability to grow on Olive
Mill Wastewater (OMW) as well as to degradate organic compounds, including aliphatic and aromatic hydrocarbons, often
accompanied by biosurfactants production. One of the most important products secreted by this microorganism is lipase
which can be exploited for several applications in the detergent, food, pharmaceutical, and environmental industries. In
addition, is able to produce citric acid and aroma from a variety of carbon sources, including sugars, alkanes,
plant oils, starch hydrolysates, ethanol, and glycerol. Thus, this chapter presents an overview of
features and its major biotechnological applications.
; morphology; physiology; bioreactors; lipase; biosurfactant; organic acids; aroma;
environment
is one of the most extensively studied ‘‘non,conventional’’ yeasts, being a strictly aerobic
microorganism capable of producing important metabolites and having an intense secretory activity, which justifies
efforts to use it in industry (as a biocatalyst), in molecular biology and in genetics studies. It is considered as
nonpathogenic and several processes based on this organism were classified as generally recognized as safe (GRAS) by
the Food and Drug Administration (FDA, USA).
Moreover, has been considered an adequate model for dimorphism studies in yeasts, since it has an
efficient system for genetic engineering transformation, and is easy to distinguish between its morphological forms, in
contrast to , which does not produce true filaments and exhibits pseudo,hyphae growth under
nitrogen,limited conditions. The yeast,to,mycelium transition is associated with unipolar growth, asymmetric division,
large polarly located vacuoles and repression of cell separation after division. It is believed that yeast dimorphism is
related to a defense mechanism to adverse conditions, such as temperature and nutritional changes.
has become a reliable, a versatile, and a popular system for the expression of heterologous proteins for
academic purposes as well as for possible commercial applications. The inherent ability of this yeast to secrete a variety
of proteins via cotranslational translocation offers added advantages. Low overglycosylation, high secretion efficiency,
good product yield, and performance reproducibility are additional features of .
One of the most important products secreted by this microorganism is lipase, which is an enzyme that attracts the
interest of scientists and industrial researchers because it can be exploited for several applications in the detergent, food,
pharmaceutical, and environmental industries. Being strictly aerobic yeast, its growth and metabolite secretion are
affected by the amount of oxygen available in the culture medium. Perfluorodecalin addition as an oxygen carrier to
culture media benefited growth rate and its extracellular enzyme production, enhancing lipase productivity.
Another approach to overcome the oxygen limitation in the culture medium is the utilization of hyperbaric air. The
effect of pressure on the yeast growth depends on the gas composition and on the pressurization mode, as well on the
microorganism and the strain. Lipase productivity was also enhanced by oxygen transfer rate improvement at increased
pressure, contrarily to what happened with cell growth, which is an indirect evidence that oxygen demand is higher for
lipase production than for cell growth. In addition, it is known that oxygen and total pressure have an important role in
the regulation of intracellular enzymes such as the ones of the β,oxidation pathway involved in the biotransformation of
ricinoleic acid into aroma. Besides castor oil, its derivatives such as methyl ricinoleate are used as substrates for aroma
production, which proved to be lipase inducers in .
Another ability of strains is to grow on Olive Mill Wastewater (OMW) based medium and
produce high,value compounds. In fact, this yeast has been used for bioremediation applications due to its cell wall
characteristics and surfactant production. In addition, , when grown under nutrient,limited conditions, is
able to produce citric acid from a variety of carbon sources, including sugars, alkanes, plant oils, starch hydrolysates,
ethanol, and raw glycerol (the main by,product of biodiesel production units).
The ability of many species of in degrading a variety of organic compounds, including aliphatic and
aromatic hydrocarbons, is often accompanied by biosurfactants production. These molecules are predominantly
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Current Research, Technology and Education Topics in Applied Microbiology and Microbial Biotechnology
A. Méndez-Vilas (Ed.)
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