Screening of yeast strains with biotechnological properties, isolated from traditional Romanian fermented foods

Yeasts have high biotechnological potential being used for obtaining
biocatalyst, biofuels, hormones, vaccines, for enhancement
of desirable flavors of food and drinks, for biocontrol
and bioremediation. In present, there is a growing interest for
characterizing new yeast strains isolated from natural fermentative
processes in order to enhance productivity in food industry.
Also, the characterization of new yeast strains able to use a
wide range of growth substrates is essential for production of
different compounds such as enzymes that can be used as food
additives. Before carrying out any tests for determination of biotechnological
potential for food industry, it is recommended to
evaluate the virulence and pathogenicity of the strains in order
to eliminate any possible threat to human health. Our study
deals with isolation and characterization of new yeast strains
from traditional Romanian fermented foods. The strains were
identified using conventional and molecular taxonomy tests
(MALDI-Tof and PCR-RFLP) followed by screening tests for
determination of virulence and pathogenicity factors. Also, we
determined biomass accumulation under stress conditions induced
by pH/temperature variations and different NaCl concentrations.
The selected strains showing no threat to human
health were subject to biodiversity studies and screening tests
for lipase production and molasses assimilation. We isolated
10 yeast strains belonging to Saccharomyces, Issatchenkia,
Hansenula and Candida genera. Most of our strains did not
produce virulence and pathogenicity factors and showed good
lipolytic activity when grown on tributiryn. Part of the strains
showed good growth rates on molasses. Molasses (produced in
large amounts in Romania) is a useful waste that can be used
for lipids and biosurfactants production, for obtaining food
additives and green pharmaceutical solvents. It is well known
that during food production and processing, microbial strains
used in different phases are exposed to physical treatments
such as heat, osmotic shock and addition of chemicals that can
influence pH values. More than 50% of the isolated strains
have shown an increased ability to grow under stress conditions
which recommends them for a wide range of applications in
food industry. Our study allowed us to select new yeast strains
with high biotechnological potential and limited human health
impact. New research directions will be developed for determination
of the mechanism of molasses assimilation and the
improvement of its biotechnological potential.

Author(s): Viorica Corbu, Ștefana PetruÈ, Ortansa Csutak

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