Search results for "Bacteriocins"
showing 10 items of 16 documents
Sng1 associates with Nce102 to regulate the yeast Pkh–Ypk signalling module in response to sphingolipid status
2016
International audience; All cells are delimited by biological membranes, which are consequently a primary target of stress-induced damage. Cold alters membrane functionality by decreasing lipid fluidity and the activity of membrane proteins. In Saccharomyces cerevisiae, evidence links sphingolipid homeostasis and membrane phospholipid asymmetry to the activity of the Ypk1/2 proteins, the yeast orthologous of the mammalian SGK1-3 kinases. Their regulation is mediated by different protein kinases, including the PDK1 orthologous Pkh1/2p, and requires the function of protein effectors, among them Nce102p, a component of the sphingolipid sensor machinery. Nevertheless, the mechanisms and the act…
Elucidating the molecular physiology of lantibiotic NAI-107 production in Microbispora ATCC-PTA-5024.
2016
Background The filamentous actinomycete Microbispora ATCC-PTA-5024 produces the lantibiotic NAI-107, which is an antibiotic peptide effective against multidrug-resistant Gram-positive bacteria. In actinomycetes, antibiotic production is often associated with a physiological differentiation program controlled by a complex regulatory and metabolic network that may be elucidated by the integration of genomic, proteomic and bioinformatic tools. Accordingly, an extensive evaluation of the proteomic changes associated with NAI-107 production was performed on Microbispora ATCC-PTA-5024 by combining two-dimensional difference in gel electrophoresis, mass spectrometry and gene ontology approaches. R…
In vitro evaluation of bacteriocinlike inhibitory substances produced by lactic acid bacteria isolated during traditional sicilian cheese making
2016
Bacteriocins are antimicrobial proteins produced by bacteria that inhibit with a bactericidal or bacteriostatic mode of action, the growth of other bacteria. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognized as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms; for this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances (BLIS), by …
Codominance of Lactobacillus plantarum and obligate heterofermentative lactic acid bacteria during sourdough fermentation
2015
Fifteen sourdoughs produced in western Sicily (southern Italy) were analysed by classical methods for their chemico-physical characteristics and the levels of lactic acid bacteria (LAB). pH and total titratable acidity (TTA) were mostly in the range commonly reported for similar products produced in Italy, but the fermentation quotient (FQ) of the majority of samples was above 4.0, due to the low concentration of acetic acid estimated by high performance liquid chromatography (HPLC). Specific counts of LAB showed levels higher than 10(8) CFU g(-1) for many samples. The colonies representing various morphologies were isolated and, after the differentiation based on phenotypic characteristics…
In situ activity of a bacteriocin-producing Lactococcus lactis strain. Influence on the interactions between lactic acid bacteria during sourdough fe…
2005
Aims: To biochemically characterize the bacteriocin produced by Lactococcus lactis ssp. lactis M30 and demonstrate its effect on lactic acid bacteria (LAB) during sourdough propagation. Methods and Results: A two-peptide bacteriocin produced by L. lactis ssp. lactis M30 was purified by ion exchange, hydrophobic interaction and reversed phase chromatography. Mass spectrometry of the two peptides and sequence analysis of the ltnA2 gene showed that the bacteriocin was almost identical to lacticin 3147. During a 20-day period of sourdough propagation the stability of L. lactis M30 was demonstrated, with concomitant inhibition of the indicator strain Lactobacillus plantarum 20, as well as the …
Caseicin, a bacteriocin from Lactobacillus casei.
1993
The intracellular bacteriocin caseicin 80 was purified from cell extracts of Lactobacillus casei strain B80. It is a thermolabile protein with an apparent molar mass of 42 kDa. As no plasmids were observed in the bacteriocinogenic strain it is assumed that caseicin is encoded by the bacterial chromosome. Using 14C-labelled precursors it was found that biosynthesis of DNA and proteins was influenced by caseicin but this inhibition is probably not the primary effect. The incorporation of fructose but not of glucose into cellular material was inhibited by caseicin.
Vibrio cholerae cytolysin: assembly and membrane insertion of the oligomeric pore are tightly linked and are not detectably restricted by membrane fl…
2000
AbstractHemolytic strains of Vibrio cholerae secrete a cytolysin that, upon binding as a monomer, forms pentameric pores in animal cell membranes. Pore formation is inhibited at low temperature and in the absence of cholesterol. We here posed the following questions: firstly, can oligomerization be observed in the absence of pore formation? Secondly, is membrane fluidity responsible for the effect of temperature or of cholesterol upon pore formation? The first issue was approached by chemical cross-linking, by electrophoretic heteromer analysis, and by electron microscopy. None of these methods yielded any evidence of a non-lytic pre-pore oligomer. The second question was addressed by the u…
Production, stability, gene sequencing and in situ anti-Listeria activity of mundticin KS expressed by three Enterococcus mundtii strains
2014
Three enterococci (WFE3, WFE20 and WFE31) selected as presumptive bacteriocin producers were found to be active against Listeria monocytogenes. In this study, due to their potential industrial/food applications, the three bacterial isolates were extensively characterized. Identification was performed by means of a combined 16S rRNA gene sequencing and multiplex PCR approach, and was confirmed with the sequencing of a partial region of a protein-encoding gene, namely pheS. The three isolates belonged unequivocally to the species Enterococcus mundtii. The randomly amplified polymorphic DNA (RAPD) analysis recognized three distinct strains. The supernatants were mainly active against Listeria …
Extension of Tosela cheese shelf-life using non-starter lactic acid bacteria
2011
Six strains of non-starter lactic acid bacteria (NSLAB) were used to extend the shelf-life of the fresh cheese Tosèla manufactured with pasteurised cows’ milk. The acidification kinetics of three Lactobacillus paracasei, one Lactobacillus rhamnosus and two Streptococcus macedonicus were studied in synthetic milk medium. Lb. paracasei NdP78 and NdP88 and S. macedonicus NdP1 and PB14-1 showed an interesting acidifying capacity and were further characterised for growth in UHT milk and production of antimicrobial compounds. Lb. paracasei NdP78 and S. macedonicus NdP1 grew more than 2 log cycles in 6 h. Lb. paracasei NdP78 was also found to produce a bacteriocin-like inhibitory substance (BLIS) …
BATTERI LATTICI CON ATTIVITA’ ANTIBATTERICA ISOLATI DA FORMAGGI TRADIZIONALI SICILIANI
2013
The study was conducted on typical Sicilian cheeses made from raw cow milk (Caciocavallo Palermitano) and sheep milk (Vastedda della valle del Belice PDO e Pecorino PDO). Genotypic identification of the LAB isolates was carried out by 16S/23S rRNA sequencing. a total of 400 bacteria strains were isolated and genotypically identified as Lactobacillus spp., Lactoccoccus spp., Pediococcus spp., Leuconostoc spp., Enterococcus spp. and Streptococcus spp. Evaluation of bacteriocin-producing LAB was investigated in vitro using the “spot on the lawn” method (2) aganist Listeria monocytogenes, Staphylococcus aureus, Salmonella enteritidis and Escherichia coli. Results showed a predominance of LAB sh…