Search results for "Nostoc"
showing 10 items of 121 documents
Kinetics of citrate uptake in growing cells ofLeuconostocspp.
1996
Citrate uptake was studied in growing cells of Leuconostoc mesenteroides subsp. mesenteroides. A Michaelis-Menten pattern with the dianionic form of citrate as the limiting substrate has been proposed. It was validated for different fermentations varying the initial citrate concentrations and the pH medium. This latter did not modify the rate of the process which was clearly confirmed using experiments with resting cells. The model was used to compare the kinetics of citrate consumption between several strains of Leuconostoc mesenteroides subsp. mesenteroides, Leuconostoc mesenteroides subsp. cremoris and Leuconostoc lactis.
A polyphasic approach in order to identify dominant lactic acid bacteria during pasta manufacturing
2010
Using a polyphasic approach, we have isolated and identified, lactic acid bacteria (LAB) in samples directly collected from an artisanal pasta-making manufactory located in Puglia (South Italy). Samples were collected during several steps of pasta processing and LAB were isolated on MRS and M17 plates. Furthermore, strains were grouped in a total of eight species by means of randomly amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) typing and 16S rDNA sequencing. The majority of strains were identified as belonging to Pediococcus pentosaceus and Enterococcus faecium species. The remaining strains were characterized and assigned to Weissella confusa, Pediococcus acidilactici,…
Effect of pHand age of culture on cellular fatty acid composition of Leuconostoc oenos
1996
Z. DRICI-CACHON, J.F. CAVIN AND C. DIVIES. 1996. This study is concerned with the fatty acid composition of three strains of Leuconostoc oenos grown at different pH. The most abundant fatty acids were C18: 1w9, C19: 0 cy(w9,10) and C16:0, followed by C16: 1w9 and C14: 0. The pH considerably modified the fatty acid distribution in Lo107 (an acidophilic strain) and Lo8413 (a moderately acidophilic strain). However, moderate changes occurred for LoATCC 23277 (a less acidophilic strain). At pH 2.9, Lo107 has a remarkably high level of C19: 0 cy-(w9,10) and C19:0 cy(w11,12). Proportions of C18: 1 and C19:0 cyclo acids varied mainly with the pH of the medium and also as a function of growth phase…
Acid tolerance inLeuconostoc oenos. Isolation and characterization of an acid-resistant mutant
1996
The acid tolerance ofLeuconostoc oenos was examined in cells surviving at pH 2.6, which is lower than the acid limit of growth (about pH 3.0). Acid-adapted cells survived better than non-adapted cells. Tolerance to acid stress was found to be dependent upon the adaptive pH. Acid resistance was increased by an order of magnitude for cultures adapted to a pH of about 2.9. Inhibiting protein synthesis with chloramphenicol prior to acid shock revealed that acid adaptation may involve two separate systems, one of which appears to be independent of protein synthesis. The acid-resistant mutant LoV8413, isolated during a long-term survival screen at pH 2.6, was found to be able to grow in acidic me…
Lactic Acid Bacteria in Spanish Red Rose and White Musts and Wines under Cellar Conditions
1992
The dynamics of the lactic acid bacterial (LAB) population in different cellars, fermentation conditions and musts were analyzed. The number of LAB in fresh musts diminished quickly in the first few days, but an increase of these bacteria occurred during the later stages of the alcoholic fermentation. The species found in fresh musts were Lactobacillus plantarum, L. hilgardii, L. brevis, L. confusus, and Leuc. onostoc paramesenteroides. At the end of fermentation only L. hilgardii, Leuc. oenos and L. fructivorans were isolated. The API 50 CHL system was not useful to identify strains of Leuc. oenos species. All the isolated strains degraded malic acid in synthetic medium but only two strain…
Microbiota of sliced cooked ham packaged in modified atmosphere throughout the shelf life
2019
Abstract Fourteen lots of cooked ham in modified atmosphere packaging (CH) were analyzed within a few days from packaging (S) and at the end of the shelf-life (E), after storage at 7 °C to simulate thermal abuse. Five more lots, rejected from the market because spoiled (R), were included in the study. Quality of the products was generally compromised during the shelf life, with only 4 lots remaining unaltered. Analysis of 16S rRNA gene amplicons resulted in 801 OTUs. S samples presented a higher diversity than E and R ones. At the beginning of the shelf life, Proteobacteria and Firmicutes dominated the microbiota, with Acinetobacter, Brochothrix, Carnobacterium, Lactobacillus, Prevotella, P…
Der Stoffwechsel verschiedener Carbons�uren durch Milchs�urebakterien
1984
The anaerobic metabolism of citrate, fumarate, gluconate, malate, 2-oxoglutarate and pyruvate by 137 strains of 23 species of lactic acid bacteria was investigated. The bacteria were from various sources (plant material, meat and dairy products, dough and wine) and belonged to the genera Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus. The ability of metabolize the acids was determined by thin layer chromatography or by enzymatic analysis after growth of the strains in a glucose-containing medium. All strains metabolized pyruvate and only 12 mainly heterofermentative strains were malate negative. These strains were also unable to decompose citrate. This acid was fermented by 23 s…
The influence of backslopping on lactic acid bacteria diversity in tarhana fermentation
2020
Tarhana is produced at batch systems in which the microbiota has changed accordingly to the microbial load from ingredients. In order to stabilize the microbiota, the effects of backslopping carried out under different temperature regimes (25 and 30 °C), pH (3.70 and 4.00) and inoculation rates (5, 10 and 15%) on lactic acid bacteria (LAB) diversity were determined in tarhana dough. LAB and Total Aerobic Mesophilic Bacteria (TAMB) numbers increased in all tarhana dough samples subjected to backslopping. Temperature and pH significantly affected the microbiological diversity of tarhana whereas the different inoculation rates did not. Tarhana dough showed complex tarhana microbiota following …
Different Modes of Regulation of the Expression of Dextransucrase in
2019
Leuconostoc lactis AV1 strain isolated from a Tunisian avocado was characterized as a dextran producer. The promoter PdsrLL and the dsrLL gene encoding the DsrLL dextransucrase responsible for the dextran synthesis were transcriptionally fused to the mCherry coding gene generating the pRCR20 plasmid. Upon plasmid transfer, both AV1n and the dextran non-producing Leuconostoc mesenteroides CM70 became red due to expression of the mCherry from the PdsrLL-dsr-mrfp transcriptional fusion. Characterization of the polymers present in cultures supernatants revealed that the DsrLL encoded from pRCR20 in the recombinant bacteria was able to synthesize dextran. The production of dextran by the DsrLL i…
The swinholide biosynthetic gene cluster from a terrestrial cyanobacterium Nostoc sp. UHCC 0450
2018
Swinholides are 42-carbon ring polyketides with a 2-fold axis of symmetry. They are potent cytotoxins that disrupt the actin cytoskeleton. Swinholides were discovered from the marine sponge Theonella sp. and were long suspected to be produced by symbiotic bacteria. Misakinolide, a structural variant of swinholide, was recently demonstrated to be the product of a symbiotic heterotrophic proteobacterium. Here, we report the production of swinholide A by an axenic strain of the terrestrial cyanobacterium Nostoc sp. strain UHCC 0450. We located the 85-kb trans-AT polyketide synthase (PKS) swinholide biosynthesis gene cluster from a draft genome of Nostoc sp. UHCC 0450. The swinholide and misaki…