Bioremoval of heavy metals by the use of microalgae.

Selenium nanoparticles as a nutritional supplement

The Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (the Panel) is asked to advise the Commission on the implications for human health of chemically defined flavouring substances used in or on foodstuffs in the Member States. In particular, the Scientific Panel is asked to evaluate the 47 flavouring substances in this Flavouring Group Evaluation 6, Revision 1 (FGE.06Rev1), using the procedure as referred to in the Commission Regulation EC No 1565/2000. These 47 flavouring substances belong to chemical groups 1 and 4 of Annex I of the Commission Regulation (EC) No 1565/2000.

Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in contact with Food (AFC) on a request from the Commission, Flavouring Group Evaluation 22: Ring-substituted phenolic substances from chemical groups 21 and 25: Question No EFSA-Q-2003-165

Selenium species, particularly the oxyanions selenite (SeO3 (2-)) and selenate (SeO4 (2-)), are significant pollutants in the environment that leach from rocks and are released by anthropogenic activities. Selenium is also an essential micronutrient for organisms across the tree of life, including microorganisms and human beings, particularly because of its presence in the 21st genetically encoded amino acid, selenocysteine. Environmental microorganisms are known to be capable of a range of transformations of selenium species, including reduction, methylation, oxidation, and demethylation. Assimilatory reduction of selenium species is necessary for the synthesis of selenoproteins. Dissimilatory reduction of selenate is known to support the anaerobic respiration of a number of microorganisms, and the dissimilatory reduction of soluble selenate and selenite to nanoparticulate elemental selenium greatly reduces the toxicity and bioavailability of selenium and has a major role in bioremediation and potentially in the production of selenium nanospheres for technological applications. Also, microbial methylation after reduction of Se oxyanions is another potentially effective detoxification process if limitations with low reaction rates and capture of the volatile methylated selenium species can be overcome. This review discusses microbial transformations of different forms of Se in an environmental context, with special emphasis on bioremediation of Se pollution.

Microbial transformations of selenium species of relevance to bioremediation

The safety and regulatory status of food, drug and cosmetics colour additives exempt from certification

Fractional determination of trimethylselenonium ion(TMSe), Se(IV) and Se(VI) in water samples was studied by graphite furnace atomic absorption spectrometry. After coexisting cations formed a complex with thiosulfate to prevent being adsorbed on cation-exchange resin, separation and concentration of TMSe were carried out by column chromatography on Dowex 50 W-X8 resin. For concentration of inorganic selenium (Se(IV), Se(VI)) in water samples, column chromatography was carried out with an anion-exchange column using Dowex 1-X4 resin and the selenium were eluted simultaneously with 1M hydrochloric acid. Se(IV) in the eluent was extracted with dithizone solution under the condition of 4M hydrochloric acid. Se(VI) could be extracted with dithizone solution after the reduction to Se(IV) with hydroxylamine hydrochloride. In this procedure, the recovery of selenium was in the ragne of 86-102.8%, and the variation coefficient was 4.2-11.3%. The detection limit of TMSe was 10ng/21 and that of Se(IV) and Se(VI) was 5ng/l.

Fractional determination of dissolved selenium compounds of trimethylselenonium ion, selenium(IV) and selenium(VI) in environmental water samples.

Biomethylation of selenium (Se) by freshwater green algae, Ankistrodesmus sp., Chlorella vulgaris and Selenastrum sp., which had been isolated from the Tone River and Lake Kasumigaura in Japan, were investigated. All of the three algae produced methylated Se compounds from the corresponding inorganic compounds. The formation of trimethylselenonium ion (TMSe) by algae reached a plateau 2-4 d after culturing and the amount of Se an TMSe was less than about 0.001% of the added Se. TMSe was also found in the algae and was in the range from 0.04 to 0.3% of total-Se accumulated in the algae. Dimethylselenide (DMSe) was found in the headspace gases of the cultured flask and was in the range from 0.001 to 0.016% of the added Se. Total-Se accumulated in the algae was in the range from 0.002 to 0.2% of added Se. The presence of arsenic in the medium inhibited DMSe formation in the algae. Green algae in the freshwater ecosystems might be related to methylation of Se, and biomethylation of Se by green algae is thought to be one of the detoxification processes.

Methylation of Inorganic Selenium Compounds by Freshwater Green Algae, Ankistrodesmus sp., Chlorella vulgaris and Selenastrum sp.

In our previous works, we reported many degradation products and reaction products of butyl hydroxy anisol (BHA) with Sodium nitrite or potassium nitrate by irradiation of UV-ray. These compounds were as follows:Reaction products: 1, 4-dimethoxy-2-nitrobenzene (I), 1-hydroxy-2-tert-butyl-4-methoxy-6-nitrobenzene (II), 1, 4-dimethoxy-2-tert-butyl-6-nitrobenzene (III), 1, 4-dihydroxy-2-tert-butyl-6-nitrobenzene (IV). Degradation products: 2-tert-butyl-quinone (V), 2-tert-butyl-hydroquinone (VI), 2-tert-butyl-1, 4-dimethoxy-benzene (VII), 2′, 3-di-tert-butyl-2-hydroxy-4′, 5-dimethoxy biphenil ether (VIII), 3, 3′-di-tert-butyl-2, 2′-dihydroxy-5, 5′-dimethoxy biphenyl (IX), 3, 3′-di-tert-butyl-2′-hydroxy-2, 5, 5′-trimethoxy biphenyl (X), 3, 3′-di-tert-butyl-2, 2′, 5, 5′-tetramethoxy biphenyl (XI)In the present paper, we studied on mutagenicity of these compounds. Compound-VI showed a notable mutagenicity in the rec-assay using wild and recombinationless strains of Bacillus subtilis and sensitivity test using wild and rad mutant strains of Yeast in comparison with original materials.

Mutagenicity of Degradation and Reaction Products of Butyl Hydroxy Anisol with Sodium Nitrite or Potassium Nitrate by Irradiation of Ultra Violet Ray

Determination of dimethyl selenide(DMSe) in the breath air of mice was studied by GC Collection of DMSe was carried out using a charcoal column(09×10cm) packed with 2g of activated charcoal granules The charcoal was transferred into a 25ml glass-stoppered tube, and the tube was placed in chilled water After 10ml of CS2 was added to the tube, the tube was immediately stoppered and the mixture was shaken for 30min The extracts were filtered through glass wool and adjusted to 10ml The extraction was repeated twice A 5μl-aliquot of the extract was injected into the GC apparatus using a VZ-7 column and the peak height of the associated component was measured (Rt=25min) The recovery was 70-76%, and the observed relative standard deviation was 42-96% The amounts of DMSe in the breath air of 10 mice after the oral administration of selenite (50 μmol-Se/kg/d) for 5 consecutive days were in a range of 32-78μg

Determination of Dimethyl Selenide in Breath Air of Mice by Gas Chromatography

https://www.jstage.jst.go.jp/article/shokueishi1960/25/4/25_4_378/_pdf

Noritaka Oyamada

Papers

Fractional determination of dissolved selenium compounds of trimethylselenonium ion, selenium(IV) and selenium(VI) in environmental water samples.

Methylation of Inorganic Selenium Compounds by Freshwater Green Algae, Ankistrodesmus sp., Chlorella vulgaris and Selenastrum sp.

Mutagenicity of Degradation and Reaction Products of Butyl Hydroxy Anisol with Sodium Nitrite or Potassium Nitrate by Irradiation of Ultra Violet Ray

Determination of Dimethyl Selenide in Breath Air of Mice by Gas Chromatography

The DNA-Damaging Activity of Natural Food Additives (Flavoring Agents)