Search results for "Nostoc"
showing 10 items of 121 documents
Vertical structure of bi-layered microbial mats from Byers Peninsula, Maritime Antarctica
2013
AbstractA summer study of the vertical structure of bi-layered microbial mats was carried out on Byers Peninsula (Livingston Island, South Shetland Islands). These benthic communities had a common basic structure that consisted of two distinct layers differing in composition, morphology and colour. Our sampling focused on mats showing more layering, which thrived over moist soils and at the bottom of ponds. The photosynthetic pigments analysis performed by high-performance liquid chromatography demonstrated a major occurrence of cyanobacteria and diatoms on these mats, the former being more abundant in relative terms on the surface and composed by morphospecies grouping into orders Oscillat…
An integrated technological approach to the selection of lactic acid bacteria of flour origin for sourdough production
2013
article i nfo Several lactic acid bacteria (LAB) were evaluated in situ for their potential in sourdough fermentation. The strains belonged to Lactobacillus plantarum, Lactobacillus sakei, Lactobacillus sanfranciscensis, Leuconostoc citreum, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides and Weissella cibaria. LAB were used, in individual inocula, to carry out the fermentation of γ-ray treated (sterile) flour and untreated commercial flour, in order to evaluate their performances both in the absence and presence of the native microbiota of flour. The pH and total titratable acidity (TTA) showed a strong and fast acidification of the experimental sourdough determined by W. cibari…
Glyphosate dose modulates the uptake of inorganic phosphate by freshwater cyanobacteria
2017
The usefulness of glyphosate [N-(phosphonomethyl)glycine] as a source of nutritive phosphorus for species of halophilic cyanobacteria has been postulated for years. Our results indicate a stimulating effect of glyphosate on the growth of four out of five examined freshwater species, Anabaena variabilis (CCALA 007), Chroococcus minutus (CCALA 055), Fischerella cf. maior (CCALA 067) and Nostoc cf. muscorum (CCALA 129), in a manner dependent on the applied concentration. The most significant stimulation was observed at a dose of 0.1 mM glyphosate. The decrease in the amount of phosphonate, which correlated with microbial growth, demonstrated that glyphosate may play an important role in cyanob…
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…
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…
Persistence of a mixed lactic acid bacterial starter culture during lysine fortification of sourdough breads by addition of pistachio powder
2020
Abstract Pistachio powder was added to flour or semolina to evaluate its contribution to increase the amount of lysine in bread. Bread production was carried out by sourdough technology using a selected 3-species (Lactobacillus sanfranciscensis/Leuconostoc citreum/Weissella cibaria) lactic acid bacterial (LAB) starter culture. All sourdoughs were subjected to a long-time fermentation (21 h) and showed levels of LAB around 109 CFU/g, indicating the suitability of pistachio powder for lactic fermentation. Yeasts were also detected, in particular in semolina trials. MiSeq Illumina technology was applied to investigate the bacterial composition of sourdoughs evidencing a different distribution …
Regulation of hdc expression and HDC activity by enological factors in lactic acid bacteria.
2008
Aims: The aim of this work was to study the influence of enological factors on the histidine decarboxylase gene (hdc) expression and on histidine decarboxylase enzyme (HDC) activity in Lactobacillus hilgardii, Pediococcus parvulus and Oenococcus oeni. Methods and Results: Cell extracts and whole cells were used. Glucose, fructose, malic acid and citric acid diminished the hdc expression. Ethanol did not increase hdc expression or activity in cells, but increased HDC activity. Temperature and pH had effect on the activity of HDC but not on hdc expression. Tartaric acid and l-lactic acid, and sulphur dioxide (SO2) had no effect on enzyme synthesis and activity. Bacterial species differ in t…
Probiotic Potential of Leuconostoc pseudomesenteroides and Lactobacillus Strains Isolated From Yaks
2018
The purpose of this study was to evaluate the antibacterial activity and safety of bacterias with probiotic potential isolated from free-ranging Tibetan yaks in high altitude regions of Tibet. For this purpose, one Leuconostoc pseudomesenteroides strain (named P1) and two Lactobacillus johnsonii and Lactobacillus mucosae strains (named LY1 and LY2), respectively, were isolated from fecal samples of Tibetan yaks. The antibacterial activity of the isolates was studied using Escherichia coli (E. coli ATCC 25922), Staphylococcus aureus (S. aureus ATCC 26112), and Salmonella enteritidis (S. enteritidis NCTC 13349) as indicator pathogens. The results showed that LY1 had high antibacterial efficac…
Purification of Leuconostoc mesenteroides citrate lyase and cloning and characterization of the citCDEFG gene cluster
1998
ABSTRACT A citrate lyase (EC 4.1.3.6 ) was purified 25-fold from Leuconostoc mesenteroides and was shown to contain three subunits. The first 42 amino acids of the β subunit were identified, as well as an internal peptide sequence spanning some 20 amino acids into the α subunit. Using degenerated primers from these sequences, we amplified a 1.2-kb DNA fragment by PCR from Leuconostoc mesenteroides subsp. cremoris . This fragment was used as a probe for screening a Leuconostoc genomic bank to identify the structural genes. The 2.7-kb gene cluster encoding citrate lyase of L. mesenteroides is organized in three open reading frames, citD , citE , and citF , encoding, respectively, the three ci…
Modulation of the growth and metabolic response of cyanobacteria by the multifaceted activity of naringenin
2017
The interactions between the plant-derived bioflavonoid, naringenin, and prokaryotic microalgae representatives (cyanobacteria), were investigated with respect to its influence on the growth and metabolic response of these microorganisms. To achieve reliable results, the growth of cyanobacteria was determined based on measurements of chlorophyll content, morphological changes were assessed through microscopic observations, and the chemical response of cells was determined using liquid and gas chromatography (HPLC; GC-FID). The results show that micromolar levels of naringenin stimulated the growth of cyanobacteria. Increased growth was observed for halophilic strains at naringenin concentra…