Visible light photocatalytic bismuth oxide coatings are effective at suppressing aquatic cyanobacteria and degrading free-floating genomic DNA

Access to safe drinking water free from microbial pollution is an issue of global concern. The use of photocatalytic thin films in water treatment has focused on titanium dioxide, which requires UV-activation, proving a potential barrier to upscaling and implementation in the real world. Visible-light-activated photocatalytic thin films, such as bismuth oxide, have recently been shown to have antimicrobial properties. However, more understanding of the photocatalytic effect on the microbial population in water is required. Glass beads coated with bismuth oxide were incubated with either Microcystis aeruginosa, Anabaena sp. or free-floating genomic DNA. The presence of bismuth oxide-coated glass beads was able to rapidly stop a population of cyanobacteria from increasing. The coated beads were also able to degrade genomic DNA. Leachate from the beads showed no increase in toxicity against human liver cells. This data demonstrates the efficacy of bismuth oxide-coated glass beads for controlling potentially dangerous cyanobacterial populations, whilst potentially reducing the amount of free-floating genomic DNA (an essential issue in the face of antimicrobial resistance) – all of which should be essential considerations in emerging water treatment technologies.     

Hydrochemical,isotopic and microbiota characterization of telese mineral waters (Southern Italy)

Environmental Geochemistry and Health - The study deals with the analyses of springs and wells at the base of Montepugliano Hill that represents the SE edge of the wide carbonate Matese massif...     

Complex performance of novel CoNiMnB electrodeposits in alkaline borohydride solutions

The complex performance of newly synthesized CoNiMnB electrodeposits in base-stabilized sodium borohydride solutions was examined. The rate of hydrogen generation due to borohydride hydrolysis was determined at different temperatures. Activation energy of approximately 33 kJ/mol was estimated, which is lower than the values reported for other catalysts. At electrochemical conditions, there is a competition between borohydride hydrolysis and electrooxidation reactions. The electrooxidation of borohydride takes place with low overpotentials at relatively high current densities. The long-term discharge at galvanostatic conditions as well as possibilities for partial storage of generated hydrogen indicates potentials for application of studied electrodeposits as anode material in direct borohydride fuel cells (DBFC).     

Relationship between conservation biology and ecology shown through machine reading of 32,000 articles

Conservation biology was founded on the idea that efforts to save nature depend on a scientific understanding of how it works. It sought to apply ecological principles to conservation problems. We investigated whether the relationship between these fields has changed over time through machine reading the full texts of 32,000 research articles published in 16 ecology and conservation biology journals. We examined changes in research topics in both fields and how the fields have evolved from 2000 to 2014. As conservation biology matured, its focus shifted from ecology to social and political aspects of conservation. The 2 fields diverged and now occupy distinct niches in modern science. We hypothesize this pattern resulted from increasing recognition that social, economic, and political factors are critical for successful conservation and possibly from rising skepticism about the relevance of contemporary ecological theory to practical conservation.     

Radioactive Isotopes of Strontium, Caesium and Plutonium in Sediments of the Northern Adriatic Sea

Sediment samples of different strata (0-3 and 12-15 cm) were collected between 1990 and 1992 during seasonal cruises in the Northern Adriatic Sea. A complete mapping of the Sr-90, Cs-137, Pu-238 and Pu-239(240) concentrations was obtained for samples covering a wide area, stretching from the Gulf of Trieste towards the Ancona shoreline. Sr-90 concentrations varied between 1.5 and 6.5 Bq kg^-1 dw, Cs-137 was in the range 0.9-38.9 Bq kg^-1 dw, Pu-239(240) in the range 0.08-1.5 Bq kg^-1 dw and Pu-238 around 0.03 Bq kg^-1 dw. Special reference was also put on the comparison between the off-shore environment and data obtained from samples collected inside the Po river delta. in spite of the major accumulation of Cs-137 inside the estuarine environment, higher concentrations of strontium and plutonium isotopes were detected in the offshore environment.     

Observations in captivity of the activity patterns and resources utilization of the spider crab <Emphasis Type="Italic">Inachus phalangium</Emphasis> (Decapoda,Majidae)

The spider crab Inachus phalangium is common in the sublitoral fringe of the Mediterranean Sea and north-eastern Atlantic Ocean, where it can be found in association with the snakelocks sea anemone Anemonia viridis. Studies concerning its activity patterns and the role of the host sea anemone are lacking. Our study aimed at investigating activity rhythms and resources utilization of I. phalangium reared in captivity. The main behavioral traits exhibited by I. phalangium are performed mostly at night. Two experiments were designed, one examined the time budget of various behavioral acts and the degree of association with the sea anemone, the other analyzed the behavioral response to algae and anemones. We showed that algae have a crucial role in the biology of I. phalangium and that crabs are ready to leave the protection of their host to obtain them. Algae represent both the major component of the diet and one of the most utilized sources of masking material of I. phalangium, which provide, together with specialized cryptic behaviors, protection against predators. Although our data suggest that the association with A. viridis is not obligatory, but the role of the snakelocks sea anemone in the life of I. phalangium is still central, both as an anti-predatory defense and as a nutritional source. The association of I. phalangium with algae and the anemone is a facultative biotrophic commensalistic symbiosis.     

Toxicity of prednisolone, dexamethasone and their photochemical derivatives on aquatic organisms

Light exposure of aqueous suspensions of prednisolone and dexamethasone causes their partial phototransformation. The photoproducts, isolated by chromatographic techniques, have been identified by spectroscopic means. Prednisolone, dexamethasone and their photoproducts have been tested to evaluate their acute and chronic toxic effects on some freshwater chain organisms. The rotifer Brachionus calyciflorus and the crustaceans Thamnocephalus platyurus and Daphnia magna were chosen to perform acute toxicity tests, while the alga Pseudokircheneriella subcapitata (formerly known as Selenastrum capricornutum) and the crustacean Ceriodaphnia dubia to perform chronic tests. The photochemical derivatives are more toxic than the parent compounds. Generally low acute toxicity was found. Chronic exposure to this class of pharmaceuticals caused inhibition of growth population on the freshwater crustacean C. dubia while the alga P. subcapitata seems to be less affected by the presence of these drugs.     

Effects of lindane on the photosynthetic apparatus of the cyanobacterium<Emphasis Type="Italic">anabaena</Emphasis>

INTENTION, GOAL, SCOPE, BACKGROUND: Cyanobacteria have the natural ability to degrade moderate amounts of organic pollutants. However, when pollutant concentration exceeds the level of tolerance, bleaching of the cells and death occur within 24 hours. Under stress conditions, cyanobacterial response includes the short-term adaptation of the photosynthetic apparatus to light quality, named state transitions. Moreover, prolonged stresses produce changes in the functional organization of phycobilisomes and in the core-complexes of both photosystems, which can result in large changes in the PS II fluorescence yield. The localization of ferredoxin-NADP+ reductase (FNR) at the ends of some peripheral rods of the cyanobacterial phycobilisomes, makes this protein a useful marker to check phycobilisome integrity. OBJECTIVE: The goal of this work is to improve the knowledge of the mechanism of action of a very potent pesticide, lindane (gamma-hexaclorociclohexane), in the cyanobacterium Anabaena sp., which can be considered a potential candidate for bioremediation of pesticides. We have studied the effect of lindane on the photosynthetic apparatus of Anabaena using fluorescence induction studies. As ferredoxin-NADP+ reductase plays a key role in the response to oxidative stress in several systems, changes in synthesis, degradation and activity of FNR were analyzed. Immunolocalization of this enzyme was used as a marker of phycobilisome integrity. The knowledge of the changes caused by lindane in the photosynthetic apparatus is essential for rational further design of genetically-modified cyanobacteria with improved biorremediation abilities. METHODS: Polyphasic chlorophyll a fluorescence rise measurements (OJIP) have been used to evaluate the vitality and stress adaptation of the nitrogen-fixing cyanobacterium Anabaena PCC 7119 in the presence of increasing concentrations of lindane. Effects of the pesticide on the ultrastructure have been investigated by electron microscopy, and FNR has been used as a marker of phycobilisome integrity. RESULTS AND DISCUSSION: Cultures of Anabaena sp. treated with moderate amounts of lindane showed a decrease in growth rate followed by a recovery after 72 hours of pesticide treatment. Concentrations of lindane below 5 ppm increased the photosynthetic performance and activity of the cells. Higher amounts of pesticide caused a decrease in these activities which seems to be due to a non-competitive inhibition of PS II. Active PS II units are converted into non-QA reducing, so called heat sink centers. Specific activity and amount of FNR in lindane-treated cells were similar to the values measured in control cultures. Release of FNR from the thylakoid after 48 hours of exposure to 5 ppm of lindane towards the cytoplasm was detected by immunogold labeling and electron microscopy. CONCLUSIONS: From these results, we conclude that the photosynthetic performance and activity of the cells are slightly increased in the presence of lindane up to 5 ppm. Moreover, in those conditions, lindane did not produce significant changes in the synthesis, degradation or activity of FNR. The high capability of Anabaena to tolerate lindane makes this cyanobacterium a good candidate for phytoremediation of polluted areas. RECOMMENDATION AND OUTLOOK: The results of this study show that cultures of Anabaena PCC 7119 tolerate lindane up to 5 ppm, without significant changes in the photosynthetic vitality index of the cells. However, a slight increase in phycobiliprotein synthesis is observed, which is related to total protein content. This change might be due to degradation of proteins less stable than phycobiliproteins. An identification of the proteins with altered expression pattern in the presence of the pesticide remains the subject of further work and will provide valuable information for the preparation of strains which are highly tolerant to lindane.     

Photocatalytic oxidation of humic substances with TiO<Subscript>2</Subscript>-coated glass micro-spheres

The photocatalytic oxidation of humic substances in aqueous solutions and natural waters with TiO₂ attached to buoyant, hollow glass micro-spheres was studied. A maximum oxidation efficiency of 3.6 mg W^–1 h^–1 was achieved in neutral or alkaline media at a plane surface concentration of the catalyst attached to the micro-spheres of 25 g m^–2. Proceeding by different mechanisms in acidic and alkaline media, the photocatalytic oxidation efficiency did not benefit from an excessive presence of hydroxyl radical promoters, hydrogen peroxide and alkali.     

Transformation of lead compounds in the soil-plant system under the influence of Bacillus and Azotobacter rhizobacteria

ABSTRACT

The study was aimed at the migration and transformation of lead compounds in the rhizosphere, its accumulation in plants under the influence of the rhizosphere bacteria. For experiment, soil samples of the technogenous ecosystem contaminated differently by lead have been selected for plant growing. The samples were subdivided into control soil and the soil, inoculated by Azotobacter and Bacillus rhizobacteria. Lead concentrations have been analysed in easily exchangeable, carbonate, organic and Fe hydroxide-associated fractions as well in chelate forms and fulvic and humic acids. In soils, inoculated by rhizobacteria, there is an increased mobilisation of lead due to its decrease in humic acids and increase in fulvic acids. On technogenic soil, rhizobacteria initiate the immobilisation of Fe-hydroxide-bound, chelate-bound lead in the rhizosphere as well as lead occurring in roots. As a results, there is a decreased lead uptake by upper parts of plants. There is also a correlation between increasing soil alkalinity and increasing Pb accumulation in the roots of plants. The results of the experiment helped to understand more about the mechanisms of Pb compound behaviour under the influence of rhizobacteria that can be used for developing biotechnologies related to soil bioremediation and crop production.