Download Stress response of some lactic acid bacteria with

Stress response of some lactic acid bacteria with bionanotehnological
applications
The first task of the project for 2016 is: Study of morphological, metabolic and
structural changes induced under thermal and saline stress conditions
Six lactic acid bacterium (LAB) strains from our laboratory collection, isolated from
Romanian artisan dairy products, fermented vegetables and other products of plant origin, such
as borș or fresh vegetables, were selected for this study. These strains have been previously
shown to have functional properties, such as production of bactericins (two strains, Grosu-Tudor
et al., 2014), exopolysaccharides (two strains, Grosu-Tudor et al., accepted for publication), and
S-layer proteins (two strains, Stefan et al., accepted for publication).
LAB strains were subjected to different stress conditions: lowest/highest incubation
temperatures at which LAB were able to grow (ranging from 15 to 42°C), and addition to the
growth medium of NaCl up to 7% (w/v). Growth was followed by measuring the pH and the
optical density of the culture at 600 nm. The biochemical changes induced by stress were
evaluated using different approaches.Total cell protein extracts were obtained by sonication. The
differences in cytosolic protein patterns were analysed by one dimensional Sodium Dodecyl
Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). The activity of some intracellular
enzymes involved in different metabolic pathways (lactate dehydrogenase, alcohol
dehydrogenase, superoxide dismutase, malate dehydrogenase, etc.) in the protein extracts were
measured by spectrophotometrical methods (Vallee and Hoch, 1993; Winterbourn et al., 1975).
The changes in their respective isoenzymes patterns were also detected by one dimensional
native polyacrylamide gel electrophoresis.
The second task of the project for 2016 is: Influence of thermal and salin stress
conditions on the production of compounds with bionanotechnological application
The biosynthesis of the bionanotechnologically important compounds (bacteriocins,
exopolysaccharides, S-layer proteins) under thermal and saline stress conditions were monitored
in terms of yield. Bacteriocins were looked for and quantified by an agar spot diffusion method
(Mayr-Harting et al., 1972), using a serial dilution of the sample. Exopolysaccharides were
isolated by acetone precipitation and gravimetrically cuantified (Degeest and De Vuyst, 1999),
while and S-layer proteins were detected by SDS-PAGE (Dohm, 2011).
Articles published:
Articles in ISI journals
1. Grosu-Tudor S.S., Brown L., Fadda S., Brezeanu A., Brinzan A., Hebert E.M, Mozzi F.,
Zamfir M. S-layer production by Lactobacillus acidophillus IBB 801 under environmental
stress conditions, Applied Microbiology and Biotechnology, 2016, DOI: 10.1007/s00253016-7355-5.
Articles in BDI journals
1. Grosu-Tudor S.S., Ștefan I.R., Zamfir M., Growth/survival of some selected lactic acid
bacteria under different stress conditions, Scientific Bulletin, Series F, Biotechnologies,
2016, vol. XX, accepted for publication
2. Ștefan I.R., Cornea P.C., Grosu-Tudor S.S., Zamfir M., Screening for S-layer production
by some lactolactobacilli from home-made fermented foods, Scientific Bulletin, Series F,
Biotechnologies, 2016, vol. XX, accepted for publication
The research team will atend the following International Conferences:
1. Grosu-Tudor S.S., Ștefan I.R., Zamfir M., Growth/survival of some selected lactic acid
bacteria under different stress conditions, The International Conference of the University
of Agronomic Sciences and Veterinary Medicine of Bucharest, Agriculture for Life, Life
for Agriculture, June 9-11 2016, Bucharest (poster).
2. Ștefan I.R., Cornea P.C., Grosu-Tudor S.S., Zamfir M., Screening for S-layer production
by some lactolactobacilli from home-made fermented foods, The International
Conference of the University of Agronomic Sciences and Veterinary Medicine of
Bucharest, Agriculture for Life, Life for Agriculture, June 9-11 2016, Bucharest (poster).
3. Grosu-Tudor S.S., Stancu M.M., Ștefan I.R., Cornea P.C., Zamfir M., Physicochemical
and rheological properties of some exopolysaccharides produced by lactic acid bacteria
isolated from plant origin materials, International Conference on Food Microbiology,
August 8-10 2016, Birmingham, England (poster).
4. Zamfir M., Stancu M.M., Ștefan I.R., Grosu-Tudor S.S., Characterization of a nisin-like
bacteriocin produced by Lactococcus lactis 19.3, isolated from raw milk, International
Conference on Food Microbiology, August 8-10 2016, Birmingham, England (poster).