Search results for "bacteri"
showing 10 items of 5466 documents
Microbial Biofilms Along a Geochemical Gradient at the Shallow-Water Hydrothermal System of Vulcano Island, Mediterranean Sea
2022
Shallow water hydrothermal vents represent highly dynamic environments where strong geochemical gradients can shape microbial communities. Recently, these systems are being widely used for investigating the effects of ocean acidification on biota as vent emissions can release high CO2 concentrations causing local pH reduction. However, other gas species, as well as trace elements and metals, are often released in association with CO2 and can potentially act as confounding factors. In this study, we evaluated the composition, diversity and inferred functional profiles of microbial biofilms in Levante Bay (Vulcano Island, Italy, Mediterranean Sea), a well-studied shallow-water hydrothermal ve…
INFLUENCE OF CITRATE NANOPARTICLES ON PHOTOCHEMICAL ACTIVITY, RESISTANCE TO PATHOGENS AND PRODUCTIVITY OF WHEAT
2021
In field experiments, increase the quantum efficiency of PSII (Fv/Fp), the Rfd-values (the chlorophyll fluorescence vitality indices) and the content of photosynthetic pigments in wheat leaves at pretreatment of wheat seeds with solutions of citrate nanoparticles has been shown. The green weight of plants at bacterial and phytoplasmas infecting at pretreatment with solutions of citrate nanoparticles, was increase, than without pre-treatment, in order: GeNPs>I-Se>SeNPs>VNPs as it has been shown. The Fv/Fp-values in leaves infected with phytoplasmas of plants at pretreatment of VNPs or I-Se solutions were more, than without pretreatment. The Fv/Fp-value in leafs with bacterial infecting at pr…
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…
Characterisation and Anaerobic Batch Degradation of Materials Accumulating in Anaerobic Digesters Treating Poultry Slaughterhouse Waste
2001
We characterised materials accumulating in two failed mesophilic semi-continuous anaerobic digesters treating poultry slaughterhouse waste and, for reference, materials in the two well-performing digesters, to find the anaerobic degradability of these materials and the factors affecting their degradation. We also studied materials accumulating and stratifying in various layers in one of the two well-performing digesters. The material from the most severely failed digesters produced methane sluggishly and did not improve appreciably even with 33 percent dilution suggesting that the recovery of failed process is slow. The methane production was apparently affected by the accumulated long-chai…
Sulphate-Reducing Laboratory-Scale High-Rate Anaerobic Reactors for Treatment of Metal- and Sulphate-Containing Mine Wastewater
2002
Upflow anaerobic sludge blanket (UASB) reactors were used in this study to evaluate the feasibility of the sulphate-reducing, anaerobic high-rate process to treat metal- and sulphate-containing mining wastewater (MWW). Four simultaneous reactors, inoculated with different inocula (mesophilic granular sludge from two UASB reactors, one treating sugar refinery wastewater and the other board mill wastewater) and operated with different loadings, were for 95 days fed with synthetic feed consisting of glucose and sulphate. In all reactors, 23-72% of sulphate and 12-93% of COD were removed. Subsequently, two reactors were fed with diluted MWW (zinc as the main metal) for 77 days with hydraulic re…
Salmo salar fish waste oil: Fatty acids composition and antibacterial activity
2020
Background and aims Fish by-products are generally used to produce fishmeal or fertilizers, with fish oil as a by-product. Despite their importance, fish wastes are still poorly explored and characterized and more studies are needed to reveal their potentiality. The goal of the present study was to qualitatively characterize and investigate the antimicrobial effects of the fish oil extracted from Salmo salar waste samples and to evaluate the potential use of these compounds for treating pathogen infections. Methods Salmo salar waste samples were divided in two groups: heads and soft tissues. Fatty acids composition, and in particular the content in saturated (SAFAs), mono-unsaturated (MUFA…
Vacuum impregnation as a tool to introduce biopreservatives in gilthead sea bream fillets (Sparus aurata)
2015
Abstract The aim of this study was to determine the possible technological uses of biopreservation and vacuum impregnation techniques to extend shelf life of gilthead sea bream fillets. Two impregnation media were studied: a solution containing lactic acid bacteria (LAB) and a nisin solution. Vacuum impregnation was carried out at 4 °C. Fillets were immersed in a vessel containing the impregnation solution and vacuum was applied during 5 min. After this time atmospheric pressure was restored leaving samples under the liquid for 5 min more. Weight gain, physico-chemical properties (moisture, pH, water activity and TVBN), color and microbiological counts were studied during 15 days of storage…
Vertical diversity of bacteria in an oxygen-stratified humic lake, evaluated using DNA and phospholipid analyses
2009
Microbes play a particularly important role in the food web in lakes with high dissolved organic carbon content. The bacterial community of a polyhumic lake, Mekkojarvi, was studied using DNA techniques and phospholipid fatty acid (PLFA) analysis during the mid-summer period of water column strati- fication. According to the 16S rRNA gene clone libraries and length heterogeneity analysis (LH-PCR), heterotrophic bacteria dominated only in the oxic epilimnion, in which various Actinobacteria (mostly cluster acI-B) and Betaproteobacteria (especially Poly- nucleobacter subcluster PnecC) were common. Se- quences assigned to heterotrophic, methylotrophic, photoautotrophic, and chemoautotrophic ge…
Remote sensing of cyanobacterial blooms in a hypertrophic lagoon (Albufera of València, Eastern Iberian Peninsula) using multitemporal Sentinel-2 ima…
2018
Eutrophy in Albufera of Valencia (Eastern Iberian Peninsula) is a quite old problem since after the intense eutrophication processes throughout the 1960s. The system shifted to a turbid stable state consolidated by the virtual disappearance of macrophytes by the early 1970s. The lagoon has been studied extensively since the 1980s, but efforts to revert the system to a clear state have not yielded the expected results because cultural eutrophication due to the growth of population in its area of influence and the effects of climate change, decreasing rainfall and increasing evaporation. This has driven to an increase in water retention times in the lagoon in recent years, resulting in a phyt…
Comprehensive dataset of shotgun metagenomes from oxygen stratified freshwater lakes and ponds
2021
Stratified lakes and ponds featuring steep oxygen gradients are significant net sources of greenhouse gases and hotspots in the carbon cycle. Despite their significant biogeochemical roles, the microbial communities, especially in the oxygen depleted compartments, are poorly known. Here, we present a comprehensive dataset including 267 shotgun metagenomes from 41 stratified lakes and ponds mainly located in the boreal and subarctic regions, but also including one tropical reservoir and one temperate lake. For most lakes and ponds, the data includes a vertical sample set spanning from the oxic surface to the anoxic bottom layer. The majority of the samples were collected during the open wate…