Search results for "bacteri"
showing 10 items of 5466 documents
Starvation can diversify the population structure and virulence strategies of an environmentally transmitting fish pathogen
2014
Background. Generalist bacterial pathogens, with the ability for environmental survival and growth, often face variable conditions during their outside-host period. Abiotic factors (such as nutrient deprivation) act as selection pressures for bacterial characteristics, but their effect on virulence is not entirely understood. “Sit and wait” hypothesis expects that long outside-host survival selects for increased virulence, but maintaining virulence in the absence of hosts is generally expected to be costly if active investments are needed. We analysed how long term starvation influences bacterial population structure and virulence of an environmentally transmitting fish pathogen Flavobacter…
Actividad antifúngica y antitoxigénica in vitro y en alimentos de bacterias ácido lácticas
2020
El desarrollo de hongos en materias primas, alimentos y piensos puede ser responsable de pérdidas económicas considerables por disminuir la calidad y reducir la vida media de todos ellos. Además, algunos hongos pueden producir compuestos potencialmente tóxicos, lo que supone un problema de seguridad alimentaria para los consumidores. La bioconservación es un concepto que se refiere al empleo de microorganismos o sus productos metabólicos en los alimentos, para inhibir el crecimiento o destruir microorganismos no deseados, con el objetivo de mejorar la seguridad, conservar la calidad y extender la vida útil de los productos alimenticios. La presente Tesis Doctoral tiene por objeto el estudio…
Parasite avoidance behaviours in aquatic environments
2018
Parasites, including macroparasites, protists, fungi, bacteria and viruses, can impose a heavy burden upon host animals. However, hosts are not without defences. One aspect of host defence, behavioural avoidance, has been studied in the terrestrial realm for over 50 years, but was first reported from the aquatic environment approximately 20 years ago. Evidence has mounted on the importance of parasite avoidance behaviours and it is increasingly apparent that there are core similarities in the function and benefit of this defence mechanism between terrestrial and aquatic systems. However, there are also stark differences driven by the unique biotic and abiotic characteristics of terrestrial …
Antibacterial Activity of Positively and Negatively Charged Hematite (α-Fe2O3) Nanoparticles to Escherichia coli, Staphylococcus aureus and Vibrio fi…
2021
This research and work has been supported by the European Regional Development Fund within the Activity 1.1.1.2 “Post-doctoral Research Aid” of the Specific Aid Objective 1.1.1 (i.e., “to increase the research and innovative capacity of scientific institutions of Latvia and the ability to attract external financing, investing in human resources and infrastructure”) of the Operational Programme “Growth and Employment” (No. 1.1.1.2/VIAA/2/18/331).
E se il punteruolo affamasse Steinernema carpocapsae?
2023
Rhynchophorus ferrugineus (Olivier 1790) (Coleoptera: Curculionidae), phytophagus of palms, has been used as a model to deepen the knowledge of the host-entomopathogen relationship. The effects of Steinernema carpocapsae (Nematoda: Steinernematidae) on the growth and immunoactivity of R. ferrugineus larvae were compared with another model insect Galleria mellonella L. (Lepidoptera: Pyralidae). Although S. carpocapsae had a negative effect on the weight and mortality of R. ferrugineus, it was not able to replicate in the hemolymph with the same rates found for the moth. In vivo and in vitro effects of S. carpocapsae on the phagocytic responsesof the hemocytes of R. ferrugineus and G. mellone…
Molecular analysis of lichen-associated bacterial communities.
2006
The bacterial communities associated with 11 different lichen samples (belonging to eight different species) from different habitats were investigated. The culturable aerobic-heterotrophic fraction of the bacterial communities was isolated from nine lichen samples on protein-rich and sugar-rich/N-free media. Thirty-four bacterial isolates were purified and pooled into groups (phylotypes) by analysis of the ribosomal internal transcribed spacer polymorphism. Twenty five phylotypes were identified, each comprising between one and three isolates. One isolate of each phylotype was partially sequenced and the resulting 16S rRNA gene sequences were compared in a phylogenetic analysis. Three gener…
Complete genome sequence of the methanogenic neotype strain Methanobacterium formicicum MF(T.).
2014
The neotype strain Methanobacterium formicicum MFT (DSM1535), a hydrogenotrophic methanogenic Archaeon, was isolated from a domestic sewage sludge digestor in Urbana (IL, USA). Here, the complete genome sequence of the methanogen is reported. The genome is 2,478,074 bp in size, featuring a GC content of 41.23%. M. formicicum MFT encodes several genes predicted to be involved in adaptation to abiotic stress such as high osmolarity. The strain MFT is of biotechnological importance since M. formicicum strains are often found in production-scale biogas plants and it is suggested as a starter culture for the anaerobic biomethanation process. (C) 2014 Elsevier B.V. All rights reserved.
Grazing intensity in subarctic tundra affects the temperature adaptation of soil microbial communities
2015
Abstract Grazing by large ungulates, such as reindeer (Rangifer tarandus L.), in subarctic tundra exerts a considerable effect on the soil microclimate. Because of higher insulation by the aboveground vegetation in light versus heavily grazed areas, soil temperatures during the growing season are considerably higher under heavy grazing. Here, we hypothesized that these grazer-induced changes in soil microclimate affect the temperature sensitivity of soil microbial activity. To test this hypothesis, we conducted soil incubations at different temperatures (4 °C, 9 °C and 14 °C) for six weeks using soils from sites with contrasting long-term grazing intensities. Microbial respiration at low te…
Genetic relationship between clinical and environmental Vibrio cholerae isolates in Tanzania: A comparison using repetitive extragenic palindromic (R…
2015
The bacterium causing cholera, Vibrio cholerae, is a marine organism and coastal waters are important reservoirs of the organism. There are more than 200 serogroups of V. cholerae, of which serogroups O1 and O139 are known to be the causative agent of the cholera. The main virulent factor in V. cholerae is cholera toxin gene (ctx) that is found from the epidemic O1 and O139 strains, but may also be found in some strains other than O1 and O139 (non-O1 and non-O139). In this study, 48 V. cholerae strains isolated from three estuaries of Tanzania and 20 stool isolates were characterized in terms of their serogroups and possession of ctx gene and then compared using two PCR based fingerprinting…
Methane-oxidizing and photoautotrophic bacteria are major producers in a humic lake with large anoxic hypolimnion
2011
Heterotrophic processes are considered to prevail in lakes with high terrestrial loading and a high content of dissolved organic carbon. However, previous studies have shown abundant methanotrophic bacteria (MOB) and photoautotrophic green sulphur bacteria (GSB) in some boreal lakes. We used genetic and lipid biomarkers to follow the seasonal succession of the abundance and carbon biomass of the major bacterial groups in Lake Mekkojarvi, a small Finnish polyhumic lake with a large anoxic hypolimnion. Biomarkers were based on length heterogeneity analysis of 16S rRNA gene amplification by polymerase chain reaction (PCR) (LH-PCR) and on phospholipid fatty acid (PLFA) analysis. Representative …