Institute of Biology Bucharest of the Romanian Academy

Bucharest, Romania

Institute of Biology Bucharest of the Romanian Academy

Bucharest, Romania

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Grosu-Tudor S.S.,Institute of Biology Bucharest of the Romanian Academy | Zamfir M.,Institute of Biology Bucharest of the Romanian Academy
Annals of the Romanian Society for Cell Biology | Year: 2012

Probiotics are live microbial food supplements which beneficially affect the host by improving the intestinal microbial balance. To be used as a probiotic, a bacterial strain must have a good tolerance to the acidity of the stomach and to the bile salts present in the upper small intestine. The purpose of the present work was to evaluate the probiotic potential of six LAB strains isolated from Romanian fermented vegetables. The strains were investigated for tolerance to acidity (pH values of 2.0, 3.0, and 4.0, respectively) and to bile salts (concentrations of 0.3% and 0.5%, w/v, respectively). All six strains tested were resistant to pH 3.0 and pH 4.0, after 24 h of incubation showing viability rates of 109 CFU/ml and 1012 CFU/ml, respectively. After 3 h of exposure to pH 2.0, four strains (Leuc. citreum 344, Lb. brevis 183, Leuc. mesenteroides 348 and Lb. plantarum 327) reached viability rates of at least 108 CFU/ml. Moreover, Lb. brevis 183 survived even after 24 h of exposure to pH 2.0, reaching a viability of 104 CFU/ml. Concerning the bile salt resistance, all six strains showed a high resistance to a concentration of 0.3% (w/v), reaching a cell viability of 105 - 108 CFU/ml after 24 h of treatment. After 2 h of exposure to 0.5% (w/v) of bile salts, the viability of strains Lb. brevis 183 and Leuc. mesenteroides 348, reached about 106 CFU/ml, a value still adequate for the use of these strains as probiotics. The high resistance to low pH values and in the presence of bile salts enables these strains to survive in the stomach and intestine, or even to compete with other bacterial groups in this environment and to colonize the GIT of the host, having a promising probiotic potential.


Tudorache M.,University of Bucharest | Gheorghe A.,University of Bucharest | Negoi A.,University of Bucharest | Enache M.,Institute of Biology Bucharest of the Romanian Academy | And 2 more authors.
Carbohydrate Polymers | Year: 2016

Bifunctional catalysts designed as carbohydrate biopolymers entrapping lipase have been investigated for the biotransformation of a natural compound (α-pinene) to oxy-derivatives. Lipases assisted the epoxidation of α-pinene using H2O2 as oxidation reagent and ethyl acetate as both acetate-supplier and solvent affording α-pinene oxide as the main product. Further, the biopolymer promoted the isomerization of α-pinene oxide to campholenic aldehyde and trans-carenol. In this case, the biopolymers played double roles of the support and also active part of the bifunctional catalyst. Screening of enzymes and their entrapping in a biopolymeric matrix (e.g. Ca-alginate and κ-carrageenan) indicated the lipase extracted from Aspergillus niger as the most efficient. In addition, the presence of biopolymers enhanced the catalytic activity of the immobilized lipase (i.e. 13.39 × 103, 19.76 × 103and 26.46 × 103 for the free lipase, lipase-carrageenan and lipase-alginate, respectively). The catalysts stability and reusability were confirmed in eight consecutively reaction runs. © 2016 Elsevier Ltd


Grosu-Tudor S.-S.,Institute of Biology Bucharest of the Romanian Academy | Stancu M.-M.,Institute of Biology Bucharest of the Romanian Academy | Pelinescu D.,University of Bucharest | Zamfir M.,Institute of Biology Bucharest of the Romanian Academy
World Journal of Microbiology and Biotechnology | Year: 2014

Lactic acid bacteria (LAB) isolated from different sources (dairy products, fruits, fresh and fermented vegetables, fermented cereals) were screened for antimicrobial activity against other bacteria, including potential pathogens and food spoiling bacteria. Six strains have been shown to produce bacteriocins: Lactococcus lactis 19.3, Lactobacillus plantarum 26.1, Enterococcus durans 41.2, isolated from dairy products and Lactobacillus amylolyticus P40 and P50, and Lactobacillus oris P49, isolated from bors. Among the six bacteriocins, there were both heat stable, low molecular mass polypeptides, with a broad inhibitory spectrum, probably belonging to class II bacteriocins, and heat labile, high molecular mass proteins, with a very narrow inhibitory spectrum, most probably belonging to class III bacteriocins. A synergistic effect of some bacteriocins mixtures was observed. We can conclude that fermented foods are still important sources of new functional LAB. Among the six characterized bacteriocins, there might be some novel compounds with interesting features. Moreover, the bacteriocin-producing strains isolated in our study may find applications as protective cultures. © 2014 Springer Science+Business Media Dordrecht.


Grosu-Tudor S.S.,Institute of Biology Bucharest of the Romanian Academy | Zamfir M.,Institute of Biology Bucharest of the Romanian Academy
Food Biotechnology | Year: 2013

A total of 139 lactic acid bacterium (LAB) strains isolated from Romanian traditionally fermented vegetables were screened for the ability to produce exopolysaccharides and for their antagonistic activity against a set of nine LAB strains, three Bacillus strains, and four Gram-negative bacteria. Eighty-five of the tested strains showed a variable antimicrobial activity against Listeria monocytogenes ATCC 1911, 35 of the strains showed a limited inhibition zone against Escherichia coli ATCC25922, and 26 strains against Salmonella enterica ATCC 14024, while 19 strains showed inhibition against one or all three Bacillus strains used as indicators. None of the tested strains showed an antimicrobial activity against Staphylococcus aureus ATCC 25923. Several strains showed antibacterial activity against more than one indicator strain. For instance, Lactobacillus plantarum 307, Lactobacillus brevis 308, and Lactobacillus plantarum/pentosus 358 were active against five of the indicator strains used, while other 23 LAB were active against three indicator strains. In the case of two strains, namely Leuconostoc citreum 344 and Lactobacillus brevis 183, the activity was maintained after neutralizing the pH of the cell-free supernatant likely due to the production of bacteriocins. The gel permeation chromatography-based screening revealed seven EPS-producing LAB strains. Two of the positive strains, namely Leuconostoc citreum 177 and Leuconostoc citreum 52, have been shown to produce large amounts of EPS, of about 20 g/L. All isolated EPS have a high molecular mass, of above 1400 KDa, and a monomer composition dominated by the presence of glucose. © 2013 Taylor and Francis Group, LLC.


Grosu-Tudor S.-S.,Institute of Biology Bucharest of the Romanian Academy | Zamfir M.,Institute of Biology Bucharest of the Romanian Academy | Van der Meulen R.,Vrije Universiteit Brussel | De Vuyst L.,Vrije Universiteit Brussel
European Food Research and Technology | Year: 2013

Traditionally fermented foods can be a rich source of diverse lactic acid bacteria (LAB) with interesting functional properties, such as exopolysaccharide (EPS) production. The objectives of this study were to map the mucoid and/or ropy LAB isolated from raw milk and traditionally fermented dairy products, collected in different regions of Romania, to study the species diversity within the samples and to further explore the EPS-producing capacity of the isolates. Seventy-three LAB strains were isolated and identified through (GTG)5-PCR genomic fingerprinting and SDS-PAGE of whole-cell proteins. Lactococcus lactis was the most frequently encountered species, followed by Lactobacillus plantarum, Leuconostoc spp., and Enterococcus spp. Nine strains produced homopolysaccharides (HoPS, glucose monomers), namely L. lactis 1.8; Leuc. citreum 1.10, 1.11, 1.12, 2.8, and 4.11; Leuc. mesenteroides 21.2; Leuc. pseudomesenteroides 20.6; and Weisella confusa/cibaria 38.2, six of them in the concentrations above 10 g/L, both in milk and MRS medium supplemented with sucrose. In all EPS, the glucose constituents were connected by different α-linkages, among which α-1,6-linkages were the most prevalent. © 2013 Springer-Verlag Berlin Heidelberg.


Zamfir M.,Institute of Biology Bucharest of the Romanian Academy | Grosu-Tudor S.-S.,Institute of Biology Bucharest of the Romanian Academy
World Journal of Microbiology and Biotechnology | Year: 2014

Understanding the mechanisms of stress response and adaptation to stress in the case of lactic acid bacteria (LAB), especially in the case of strains with functional properties, is very important when such strains are potential candidates for starter cultures or probiotics. In this context, our study shows the response of some LAB [four exopolysaccharide (EPS)-producing strains and one strain with potential probiotic effect] to the stresses induced by low and high incubation temperatures, acidity, NaCl, and bile salts, often encountered during the technological processes in food or during the passage through the human gastro-intestinal tract. The strains were able to grow at temperatures up to 40 °C (the mesophilic strains) and 47 °C (the thermophilic strain), in medium with an initial pH of at least 4.0 (Lactobacillus acidophilus IBB801), or in the presence of NaCl up to 10 % (Weissella confusa/cibaria 38.2), or bile salts up to 0.2 % (L. acidophilus IBB801). The protein and isoenzyme patterns of the strains subjected to various stress conditions presented several differences compared with the control patterns, among which the overexpression of some proteins of about 50-60 kDa, differences in the bands intensity in the case of the intracellular enzymes, or the complete loss of some of these bands. The best survival to low pH values and high temperatures was observed for strain L. acidophilus IBB801, the candidate probiotic strain. The EPS production of the four tested strains was, in general, directly related to the growth, the highest yields being obtained when strains were incubated at 24 °C. © 2013 Springer Science+Business Media Dordrecht.


For the first time we describe the morphology and anatomy of mature achenes bearing fertile seeds of Pietrosia laevitomentosa, an endemic plant species in the Eastern Carpathians. The new diagnostic features of the genus Pietrosia justify its taxonomic recognition as separate from Andryala; those are the achene size (between 2.5 and 4.3 mm long), the deciduous pappus, the single-rimmed achene apex, the elongate exocarpic cells, the complete ring of mesocarpic sclerenchyma (up to 11-layered), and the number and localization of the vascular bundles (5 bundles, in the small ribs). Furthermore, our data may also serve to reconsider the species ecology and conservation strategies. © 2015 Magnolia Press.


PubMed | CONICET and Institute of Biology Bucharest of the Romanian Academy
Type: Journal Article | Journal: Applied microbiology and biotechnology | Year: 2016

The ability of microorganisms to synthesize S-layer, the outermost structure of the microbial cell envelope composed of non-covalently bound proteins, has been ascribed to help microorganisms to exert their probiotic properties in the host. In this work, formation of S-layer by the potentially probiotic strain Lactobacillus acidophilus IBB 801 under different stress culture conditions (high incubation temperatures, presence of bile salts or NaCl, and acidic pH) was assayed. A marked S-layer synthesis by L. acidophilus IBB 801 was detected when the strain was grown at 42C and in the presence of 0.05% bile salts or 2.0% NaCl. The presence of S-layer proteins was further confirmed by transmission electron microscopy and protein identification by MS/MS. The differential expression of the proteome of this strain at 42C, when a marked formation of S-layer was detected, revealed the overexpression of six proteins mainly related to general stress and protein biosynthesis and translation, while four proteins detected in lower amounts were involved in DNA repair and energy metabolism. As L. acidophilus IBB 801 produces both a bacteriocin and S-layer proteins, the strain could be of interest to be used in the formulation of functional food products with specific properties.


PubMed | Institute of Biology Bucharest of the Romanian Academy and University of Bucharest
Type: | Journal: Carbohydrate polymers | Year: 2016

Bifunctional catalysts designed as carbohydrate biopolymers entrapping lipase have been investigated for the biotransformation of a natural compound (-pinene) to oxy-derivatives. Lipases assisted the epoxidation of -pinene using H2O2 as oxidation reagent and ethyl acetate as both acetate-supplier and solvent affording -pinene oxide as the main product. Further, the biopolymer promoted the isomerization of -pinene oxide to campholenic aldehyde and trans-carenol. In this case, the biopolymers played double roles of the support and also active part of the bifunctional catalyst. Screening of enzymes and their entrapping in a biopolymeric matrix (e.g. Ca-alginate and -carrageenan) indicated the lipase extracted from Aspergillus niger as the most efficient. In addition, the presence of biopolymers enhanced the catalytic activity of the immobilized lipase (i.e. 13.3910(3), 19.7610(3)and 26.4610(3) for the free lipase, lipase-carrageenan and lipase-alginate, respectively). The catalysts stability and reusability were confirmed in eight consecutively reaction runs.


PubMed | Institute of Biology Bucharest of the Romanian Academy
Type: Journal Article | Journal: World journal of microbiology & biotechnology | Year: 2014

Understanding the mechanisms of stress response and adaptation to stress in the case of lactic acid bacteria (LAB), especially in the case of strains with functional properties, is very important when such strains are potential candidates for starter cultures or probiotics. In this context, our study shows the response of some LAB [four exopolysaccharide (EPS)-producing strains and one strain with potential probiotic effect] to the stresses induced by low and high incubation temperatures, acidity, NaCl, and bile salts, often encountered during the technological processes in food or during the passage through the human gastro-intestinal tract. The strains were able to grow at temperatures up to 40 C (the mesophilic strains) and 47 C (the thermophilic strain), in medium with an initial pH of at least 4.0 (Lactobacillus acidophilus IBB801), or in the presence of NaCl up to 10% (Weissella confusa/cibaria 38.2), or bile salts up to 0.2% (L. acidophilus IBB801). The protein and isoenzyme patterns of the strains subjected to various stress conditions presented several differences compared with the control patterns, among which the overexpression of some proteins of about 50-60 kDa, differences in the bands intensity in the case of the intracellular enzymes, or the complete loss of some of these bands. The best survival to low pH values and high temperatures was observed for strain L. acidophilus IBB801, the candidate probiotic strain. The EPS production of the four tested strains was, in general, directly related to the growth, the highest yields being obtained when strains were incubated at 24 C.

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