Search results for "Bacteriology"

Effect of pH and nitrite concentration on nitrite oxidation rate

2011

The effect of pH and nitrite concentration on the activity of the nitrite oxidizing bacteria (NOB) in an activated sludge reactor has been determined by means of laboratory batch experiments based on respirometric techniques. The bacterial activity was measured at different pH and at different total nitrite concentrations (TNO 2). The experimental results showed that the nitrite oxidation rate (NOR) depends on the TNO 2 concentration independently of the free nitrous acid (FNA) concentration, so FNA cannot be considered as the real substrate for NOB. NOB were strongly affected by low pH values (no activity was detected at pH 6.5) but no inhibition was observed at high pH values (activity wa…

Erbium Family Laser and Nd:YAG Laser Impact on Bacteriology and Fungi in Dentistry

2021

Lai gan zobārstniecībā pielietojamie lāzeri tiek izmantoti salīdzinoši nesen ir veikts liels daudzums klīnisko pētījumu ,kuros novērtēta gan to efektivitāte ,baktericīdā iedarbība, gan klīniskais sniegums. Er:YAG, Er,Cr:YSGG un Nd:YAG ir visdaudzsološākie zobārstniecībā izmantojamie lāzeri, ko nosaka to multifunkcionālais pielietojums un pretmikrobā efektivitāte. Galvenais uzsvars šajā darbā vērsts uz Er:YAG, Er,Cr:YSGG un Nd:YAG, analizējot to bakterioloģisko un pretmikrobo darbību.

Polar Localization of a Tripartite Complex of the Two-Component System DcuS/DcuR and the Transporter DctA in Escherichia coli Depends on the Sensor K…

2014

The C4-dicarboxylate responsive sensor kinase DcuS of the DcuS/DcuR two-component system of E. coli is membrane-bound and reveals a polar localization. DcuS uses the C4-dicarboxylate transporter DctA as a co-regulator forming DctA/DcuS sensor units. Here it is shown by fluorescence microscopy with fusion proteins that DcuS has a dynamic and preferential polar localization, even at very low expression levels. Single assemblies of DcuS had high mobility in fast time lapse acquisitions, and fast recovery in FRAP experiments, excluding polar accumulation due to aggregation. DctA and DcuR fused to derivatives of the YFP protein are dispersed in the membrane or in the cytosol, respectively, when …

Insights into genome plasticity of the wine-making bacterium Oenococcus oeni strain ATCC BAA-1163 by decryption of its whole genome.

2008

International audience; Studying genomes of O. oeni strains having opposite oenological aptitudes is important for understanding why this lactic acid bacterium involved in malolactic fermentation is so well adapted to wine. Here, the genome of a strain ATCC BAA-1163, is described and compared with the recently reported genome of the better wine-adapted strain PSU-1. The BAA-1163 genome (8X) was obtained by shotgun sequencing and Phrap assembling. Compact and 62% AT-rich, it consists of a circular 1,792,103-bp chromosome and a 3,948-bp plasmid. It was analysed through a CAAT-Box annotation platform and manually inspected. A total of 51 RNA genes were detected, including two rRNA operons (the…

Prevalence of Mycobacterium bovis in agroecosystems : analysis of potential environmental reservoirs (soil, fresh water, soil fauna and aquatic fauna…

2016

Bovine tuberculosis is an infectious disease caused by Mycobacterium bovis. This disease affects cattle, and many species of domestic and wild mammals, and humans. The circulation of the bacteria in various multi-host systems promotes the maintenance of the disease and the contamination of cattle in the vicinity. Beside direct transmission of the bacteria through the respiratory route, indirect transmission, through inhalation or ingestion of environmental matrices contaminated by an infected animal excretory, is suspected in several countries. Environmental contamination with M. bovis appears to be a crucial factor in the persistence of the infection in multi-host systems. In Côte d'Or, a …

Influence of fermented food consumption on oral microbiota and taste perception

2022

Screening of Lactococcus lactis starters with Absorbance Reduction Activity Method (ARAm)

2022

Lactococcus lactis is one of the most used species in the dairy industry. This species has the ability to reduce to very negative values the redox potential (Eh) of food matrices, making it one of the most reducing Lactic Acid Bacteria (LAB) [1]. This reducing activity influences oxidation-reduction reactions involved in the organoleptic quality of the product and prevents the undesired microorganisms development [2–4]. The main mechanism involved are exofacial thiol groups, NoxE NADH Oxidase and the Electron Transport Chain mechanism [5-7]. For Eh measurement, the commonly used method consists of a redox probe placed in a liquid medium or food matrix [8]. With this probe, Cachon et al. (20…

Ecology of N2O reducing bacteria in arable soils

2016

Nitrous oxide (N2O) is an important greenhouse gas (GHG) and the main ozone depleting substance. Agricultural soils are the main anthropogenic-induced source of this GHG. The concentration of N2O in the atmosphere is steadily increasing, but we still lack knowledge on the factors controlling its production and consumption in soils. The reduction of N2O to N2 by microorganisms harboring the N2O reductase gene (nosZ) is the only known biological process able to consume this GHG. Recent studies revealed a previously unknown clade of N2O-reducers which was shown to be important to the N2O sink capacity of soils. This thesis seeks to gain a greater understanding on the ecology of N2O-reducers in…

Les souches d’Escherichia coli résistantes aux antibiotiques

2017

Parmi les bactéries multi-résistantes, les entérobactéries productrices de β-lactamase à spectre élargi (BLSE) occupent une place croissante. Parmi celles-ci, c’est Escherichia coli (entérobactérie commensale du tube digestif de l’homme et de l’animal) qui est l’espèce la plus concernée par cette production enzymatique. Cependant, il existe peu de données sur l’existence de réservoirs environnementaux pour ces souches, leur capacité à survivre dans l’environnement et en particulier dans les eaux douces et dans les sols. Le projet "CIREC" visait donc à étudier la prévalence et la caractérisation des souches d’E.coli productrices de BLSE de type CTX-M dans les eaux usées et les boues issues d…

Sensitivity to acetic acid, ability to colonize abiotic surfaces and virulence potential of Listeria monocytogenes EGD-e after incubation on parsley …

2010

International audience; Abstract Aim: To investigate how the survival of Listeria monocytogenes on parsley leaves may affect its ability to sustain process-related harsh conditions and its virulence. Methods and Results: Parsley seedlings were spot inoculated with stationary phase cells of L. monocytogenes EGD-e and incubated for 15 days. Each day, bacterial cells were harvested and enumerated, and their ability to survive acetic acid challenge (90 min, pH 4.0), to colonize abiotic surfaces and to grow as biofilms was assessed. After a 3-log decrease over the first 48 h, the population stabilized to about 10(6) CFU g(-1) until the sixth day. After the sixth day, L. monocytogenes was no long…