Search results for "Nostoc"

Biodiversity and dairy traits of indigenous milk lactic acid bacteria grown in presence of the main grape polyphenols

2020

ABSTRACT The present work was developed to select lactic acid bacteria (LAB) to be used as starter cultures in functional cheese production. The indigenous milk LAB populations were isolated from fermented raw ewes’ milks (four bulks) added with 0.5 mg/mL of nine polyphenols commonly found in winery by-products. After 48 h of fermentation, all milks were characterized by an increase of LAB levels of about 3–4 Log cycles. All different colonies were purified and characterized for the main physiological and biochemical traits and then differentiated genetically at strain level and identified. Ten species belonging to the LAB genera Lactobacillus, Streptococcus, Enterococcus, Leuconostoc and L…

Cloning of branched chain amino acid biosynthesis genes and assays of alpha-acetolactate synthase activities in Leuconostoc mesenteroides subsp. crem…

1999

A genomic library from Leuconostoc mesenteroides subsp. cremoris (Lmc) in Escherichia coli was screened for alpha-acetolactate synthase (ALS) activity using a phenotypic test detecting the production of acetolactate or related C4 derivatives (diacetyl, acetoin or 2,3-butanediol) in the culture. Four recombinant E. coli clones, with plasmids containing overlapping DNA fragments and displaying anabolic ALS activity, were selected. This activity is encoded by an ilvB gene belonging to a putative operon which contains genes highly similar to the genes of the branched chain amino acid (BCAA) operon of Lactococcus lactis subsp. lactis. This putative BCAA operon is not functional as the ilvA gene …

Genomic Insights Into Five Strains of Lactobacillus plantarum With Biotechnological Potential Isolated From chicha, a Traditional Maize-Based Ferment…

2019

Lactic acid bacteria (LAB) are indigenous microorganisms that have been involved in food fermentations throughout history to preserve food and also to give special characteristics to them. The traditional fermented foods that are still being elaborated in indigenous populations around the world are a potential source of LAB with important biotechnological properties and/or beneficial to health. In a previous work, LAB biodiversity associated with chicha, a traditional maize-based fermented beverage from Northwestern Argentina, was studied, both by culture dependent and independent methods. From that study, 392 isolates were recovered, mostly members of Lactobacillus and Leuconostoc. Biotech…

Different Modes of Regulation of the Expression of Dextransucrase in Leuconostoc lactis AV1n and Lactobacillus sakei MN1

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…

A selective medium for the isolation of malolactic mutants of Leuconostoc oenos

1994

We have developed a selective medium for the isolation of Leuconostoc oenos mutants defective in malolactic fermentation. Forty per cent of colonies isolated directly on selective plates after UV mutagenesis had lost their ability to degrade malate. None of the tested mutants showed any detectable malolactic activity and all lacked a protein band corresponding in size to that of the malolactic enzyme. The availability of such mutants provides a valuable tool both for physiological and genetic research on malolactic fermentation.

Oligopeptide assimilation and transport by Oenococcus oeni

2008

International audience; Aims: Oenococcus oeni is a slow-growing wine bacterium with a low growth yield. It thrives better on complex nitrogen sources than on free amino-acid medium. We aimed to characterize the oligopeptide use of this micro-organism. Methods and Results: Several peptides of two to eight amino-acid residues were able to provide essential amino acids. The disappearance of various peptides from extracellular medium was assessed with whole cells. Initial rates of utilization varied with the peptide, and free amino acids were released into the medium. Conclusions: Oenococcus oeni was able to transport the oligopeptides with two to five amino-acid residues tested and to hydrolys…

Morphological determination of the phototrophic community composition of biological soil crusts in coastal sand dunes in northern Germany

2022

This dataset comprises the microbial community composition of biological soil crusts in north-German sand dunes. For this we obtained enrichment cultures of phototrophic microorganisms, by placing fragments of biocrusts of the same Petri dishes as used for sequencing, in Petri dishes with Bold Basal (1N BBM) agarized medium (Bischoff and Bold 1963). Cultures were grown under standard laboratory conditions: with a 12-hour alteration of light and dark phases and irradiation of 25 μmol photons m-2 s-1 at a temperature 20 ± 5 ºС. Microscopic study of these raw cultures began in the third week of cultivation. Morphological examinations were performed using Olympus BX53 light microscope with Noma…

The putative PAINs nostotrebin 6 and derivatives from Nostoc sp. inhibit the trypanosomal cysteine protease rhodesain

2017

Nitrogen fixation and methanotrophy in forest mosses along a N deposition gradient

2013

Abstract Nitrogen deposition has decreased the plant-associated nitrogen (N 2 ) fixation when measured using the indirect acetylene reduction assay (ARA). However, nitrogen deposition can also lead to changes in the diversity of moss symbionts, e.g. affect methanotrophic N 2 fixation, which is not measured by ARA. To test this hypothesis we compared ARA with the direct stable isotope method ( 15 N 2 incorporation) and studied methanotrophy in two mosses, Hylocomium splendens and Pleurozium schreberi , collected from seven forest sites along a boreal latitudinal N deposition transect. We recognized that the two independent N 2 fixation measures gave corresponding results with the conversion …

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…