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J Bioenerg Biomembr ; 45(5): 491-504, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23625488


In this study we investigated the effects of exogenous and endogenous oxidative stress on mitochondrial membrane permeability transition in yeast cells. E. magnusii yeast was used in the study as it is the only yeast strain possessing a natural high-capacity Са²âº transport system. The key reactive oxygen species (ROS) detoxifying enzymes in the yeast cells--catalases (CATs) and superoxide dismutases (SODs)--were fully characterized. At least five isoforms of SODs and only one isoform of CATs were found in the E. magnusii mitochondria. The assessment of the main properties of mitochondrial non-specific permeability under physiological conditions such as dynamics of the membrane potential (∆Ψ) and swelling in mitochondria showed that under physiological conditions classical inhibitors of CATs (ATZ--3-amino-1, 2, 4-triazole) and of SODs (DDC--diethyldithiocarbamate) caused irreversible decline in ∆Ψ in the yeast mitochondria. This decline was accelerated in the presence of 500 µM Са²âº. The combined action of the inhibitors (ATZ + DDC) promoted moderate swelling in the isotonic medium, which was confirmed by transmission electron microscopy. Mitochondrial swelling in the cells exposed to antioxidant system inhibitors was accompanied by typical signs of early apoptosis, namely by chromatin margination and condensation, vacuolization of the cytosol, and damage of the plasma membrane. Here we showed, at both cellular and mitochondrial levels, that the deregulation of oxidant-scavenging enzymes directly leads to the opening of the mPTP, followed by induction of apoptotic markers in the whole yeast cells. Our studies are the first to clarify the highly contradictory data in the literature on mPTP in yeast mitochondria.

Antioxidantes/metabolismo , Cálcio/metabolismo , Endomyces/enzimologia , Inibidores Enzimáticos/farmacologia , Mitocôndrias/metabolismo , Permeabilidade da Membrana Celular/efeitos dos fármacos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Membranas Mitocondriais/efeitos dos fármacos , Membranas Mitocondriais/metabolismo , Estresse Oxidativo/fisiologia , Permeabilidade , Espécies Reativas de Oxigênio/metabolismo
Syst Appl Microbiol ; 32(6): 438-48, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19243908


Thirty samples of Italian durum wheat semolina and whole durum wheat semolina, generally used for the production of Southern Italy's traditional breads, were subjected to microbiological analysis in order to explore their lactic acid bacteria (LAB) diversity and to find strains with antifungal activity. A total of 125 presumptive LAB isolates (Gram-positive and catalase-negative) were characterized by repetitive extragenic palindromic-PCR (REP-PCR) and sequence analysis of the 16S rRNA gene, leading to the identification of the following species: Weissella confusa, Weissella cibaria, Leuconostoc citreum, Leuconostoc mesenteroides, Lactococcus lactis, Lactobacillus rossiae and Lactobacillus plantarum. The REP-PCR results delineated 17 different patterns whose cluster analysis clearly differentiated W. cibaria from W. confusa isolates. Seventeen strains, each characterized by a different REP-PCR pattern, were screened for their antifungal properties. They were grown in a flour-based medium, comparable to a real food system, and the resulting fermentation products (FPs) were tested against fungal species generally contaminating bakery products, Aspergillus niger, Penicillium roqueforti and Endomyces fibuliger. The results of the study indicated a strong inhibitory activity - comparable to that obtained with the common preservative calcium propionate (0.3% w/v) - of ten LAB strains against the most widespread contaminant of bakery products, P. roqueforti. The screening also highlighted the unexplored antifungal activity of L. citreum, L. rossiae and W. cibaria (1 strain), which inhibited all fungal strains to the same or a higher extent compared with calcium propionate. The fermentation products of these three strains were characterized by low pH values, and a high content of lactic and acetic acids.

Antibiose , Pão/microbiologia , Ecossistema , Contaminação de Alimentos/prevenção & controle , Fungos/crescimento & desenvolvimento , Lactobacillaceae , Streptococcaceae , Triticum/microbiologia , Ácido Acético/metabolismo , Ácido Acético/farmacologia , Aspergillus niger/efeitos dos fármacos , Aspergillus niger/crescimento & desenvolvimento , Endomyces/efeitos dos fármacos , Endomyces/crescimento & desenvolvimento , Fungos/classificação , Fungos/efeitos dos fármacos , Itália , Ácido Láctico/metabolismo , Ácido Láctico/farmacologia , Lactobacillaceae/genética , Lactobacillaceae/crescimento & desenvolvimento , Lactobacillaceae/isolamento & purificação , Lactobacillaceae/metabolismo , Lactobacillus/genética , Lactobacillus/crescimento & desenvolvimento , Lactobacillus/isolamento & purificação , Lactobacillus/metabolismo , Lactobacillus plantarum/genética , Lactobacillus plantarum/crescimento & desenvolvimento , Lactobacillus plantarum/isolamento & purificação , Lactobacillus plantarum/metabolismo , Leuconostoc/genética , Leuconostoc/crescimento & desenvolvimento , Leuconostoc/isolamento & purificação , Leuconostoc/metabolismo , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Penicillium/efeitos dos fármacos , Penicillium/crescimento & desenvolvimento , Reação em Cadeia da Polimerase/métodos , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Streptococcaceae/genética , Streptococcaceae/crescimento & desenvolvimento , Streptococcaceae/isolamento & purificação , Streptococcaceae/metabolismo , Triticum/efeitos dos fármacos