Fucus vesiculosus extracts that have both radical scavenging activity and metal chelating ability in vitro were used as natural antioxidant in granola bars enriched with fish oil emulsion by using primary and secondary emulsion systems stabilized by sodium caseinate alone and sodium caseinate–chitosan. The bars were stored at 20 °C and evaluated over a period of 10 weeks by measuring the development of primary and secondary oxidation products. The samples prepared with secondary emulsion system developed less oxidation products probably due to increased interfacial layer thickness that would act as a barrier to the penetration and diffusion of molecular species that promote oxidation. The positive charge of oil droplets in the secondary emulsion may also inhibit iron–lipid interaction through electrostatic repulsion. Additional protection against lipid oxidation was obtained when fish oil emulsions were added to the granola bars especially in combination with acetone and ethanol extracts of Fucus vesiculosus.
Flokkur: Greinar
The drying characteristics and lipid oxidation in brined and blanched whole capelin were studied during controlled low temperature drying to establish the influence of lipid content and blanching. Drying characteristics (moisture content, drying rate and water activity) and lipid oxidation indicators (PV, TBARS and color) were determined. Drying was influenced by blanching as well as the lipid level. Moisture content at equilibrium for brined and blanched high lipid dried capelin was 20 and 13% (aw, 0.69 and 0.62), whereas counterpart low lipid groups had 19 and 11% (Aw, 0.67 and 0.59) accordingly after 184 h of drying. Changes in PV, TBARS and color were observed as drying progressed with brined capelin exhibiting more stability in the attributes than blanched capelin. Blanched and low lipid capelin dried faster; however, blanching resulted to increased yellowness color making it unpopular for capelin drying.
A novel hyperthermophilic, piezophilic, anaerobic archaeon, designated NCB100T, was isolated from a hydrothermal vent flange fragment collected in the Guaymas basin at the hydrothermal vent site named ‘Rebecca’s Roost’ at a depth of 1997 m. Enrichment and isolation were performed at 100 °C under atmospheric pressure. Cells of strain NCB100T were highly motile, irregular cocci with a diameter of ~1 µm. Growth was recorded at temperatures between 70 and 112 °C (optimum 105 °C) and hydrostatic pressures of 0.1–80 MPa (optimum 40–50 MPa). Growth was observed at pH 3.5–8.5 (optimum pH 7) and with 1.5–7 % NaCl (optimum at 2.5–3 %). Strain NCB100T was a strictly anaerobic chemo-organoheterotroph and grew on complex proteinaceous substrates such as yeast extract, peptone and tryptone, as well as on glycogen and starch. Elemental sulfur was required for growth and was reduced to hydrogen sulfide. The fermentation products from complex proteinaceous substrates were CO2 and H2. The G+C content of the genomic DNA was 41.3 %. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain NCB100T belongs to the genus Pyrococcus, showing 99 % similarity with the other described species of the genus Pyrococcus. On the basis of physiological characteristics, DNA G+C content, similarity level between ribosomal proteins and an average nucleotide identity value of 79 %, strain NCB100T represents a novel species for which the name Pyrococcus kukulkanii sp. nov. is proposed. The type strain is NCB100T (=DSM 101590T=Souchothèque de Bretagne BG1337T).
Transcriptomes were analyzed for two related hyperthermophilic archaeal species, the piezophilic Thermococcus barophilus strain MP and piezosensitive Thermococcus kodakarensis strain KOD1 subjected to high hydrostatic pressures. A total of 378 genes were differentially expressed in T. barophilus cells grown at 0.1, 40 and 70 MPa, whereas 141 genes were differentially regulated in T. kodakarensis cells grown at 0.1 and 25 MPa. In T. barophilus cells grown under stress conditions (0.1 and 70 MPa), 178 upregulated genes were distributed among three clusters of orthologous groups (COG): energy production and conversion (C), inorganic ion transport and metabolism (P) and carbohydrate transport and metabolism (G), whereas 156 downregulated genes were distributed among: amino acid transport and metabolism (E), replication, recombination and repair (L) and nucleotide transport and metabolism (F). The expression of 141 genes was regulated in T. kodakarensis cells grown under stress conditions (25 MPa); 71 downregulated genes belong to three COG: energy production and conversion (C), amino acid transport and metabolism (E) and transcription (K), whereas 70 upregulated genes are associated with replication, recombination and repair (L), coenzyme transport (H) and defense mechanisms (V).
Seaweeds have recently been shown to contain a significant proportion of arsenic in the form of arsenolipids (AsLp). Three strains of the filamentous brown alga Ectocarpus species were grown in the laboratory with different simulations of environmental stress: control conditions (1/2 Provasoli-enriched seawater), low nitrate (30 % of the amount of nitrates in the control), low phosphate (30 % of the amount of phosphate in the control) and under oxidative stress levels (2 mM H2O2). Generally, the major AsLp was an arsenic-containing hydrocarbon, AsHC360 (50–80 %), but additionally, several arsenic-containing phospholipids (AsPL) were identified and quantified using high-performance liquid chromatography–inductively coupled plasma mass spectrometry and electrospray ionisation mass spectrometry (HPLC-ICP-MS/ESI-MS). The AsLps in cultures were compared with AsLps in Ectocarpus found in its natural habitat as well as with other brown filamentous algae. The AsLp and arsenosugar profiles differed depending on the experimental conditions. Under low phosphate conditions, a significant reduction of phosphorus-containing arsenosugars was noticed, and a significant increase of phosphate-containing AsLps was found when compared with the controls. Strains grown under oxidative stress showed a significant increase in AsLps as well as clear physiological changes.
Regulators have been reluctant to set maximum levels (ML) for arsenic in food because of the molecular diversity of the arsenic species present. Arsenic levels in food can vary by several orders of magnitude, with the arsenic present in many different molecular forms which vary substantially in toxicity. Arsenic in food is found as a multitude of different organoarsenic species and as inorganic arsenic (iAs). iAs is regarded as the most toxic form of arsenic in food and feed and is classified as a carcinogen by the International Agency for Research on Cancer (IARC). Organoarsenic species are, in general, believed to be of low toxicity or even non-toxic, e.g., most of the arsenic in fish occurs as non-toxic arsenobetaine.
Lipid and microbial quality of smoked capelin (two groups differing in lipid content) and sardine was studied, with the aim of introducing capelin in the smoked sardine markets. Lipid hydrolysis (phospholipid and free fatty acids) and oxidation index (hydroperoxides and thiobarbituric acid-reactive substances), fatty acid composition, and total viable count were measured in raw and packaged smoked fish during chilled storage (day 2, 10, 16, 22, 28). Lipid hydrolysis was more pronounced in low lipid capelin, whereas accelerated lipid oxidation occurred in high lipid capelin. Muscle lipid was less stable in sardine than capelin. Essential polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid) constituted 12% of fatty acids in capelin and 19% in sardine. Vacuum packaging as well as hot smoking retarded bacterial growth, recording counts of ≤log 5 CFU/g compared to ≥log 7CFU/g in cold smoked air packaged. Smoked low lipid capelin was considered an alternative for introduction in smoked sardine markets.
Colonization of life on Surtsey has been observed systematically since the formation of the island 50 years ago. Although the first colonisers were prokaryotes, such as bacteria and blue–green algae, most studies have been focused on the settlement of plants and animals but less on microbial succession. To explore microbial colonization in diverse soils and the influence of associated vegetation and birds on numbers of environmental bacteria, we collected 45 samples from different soil types on the surface of the island. Total viable bacterial counts were performed with the plate count method at 22, 30 and 37 °C for all soil samples, and the amount of organic matter and nitrogen (N) was measured. Selected samples were also tested for coliforms, faecal coliforms and aerobic and anaerobic bacteria. The subsurface biosphere was investigated by collecting liquid subsurface samples from a 181 m borehole with a special sampler. Diversity analysis of uncultivated biota in samples was performed by 16S rRNA gene sequences analysis and cultivation. Correlation was observed between nutrient deficits and the number of microorganisms in surface soil samples. The lowest number of bacteria (1 × 104–1 × 105 cells g−1) was detected in almost pure pumice but the count was significantly higher (1 × 106–1 × 109 cells g−1) in vegetated soil or pumice with bird droppings. The number of faecal bacteria correlated also to the total number of bacteria and type of soil. Bacteria belonging to Enterobacteriaceae were only detected in vegetated samples and samples containing bird droppings. The human pathogens Salmonella, Campylobacter and Listeria were not in any sample. Both thermophilic bacteria and archaea 16S rDNA sequences were found in the subsurface samples collected at 145 and 172 m depth at 80 and 54 °C, respectively, but no growth was observed in enrichments. The microbiota sequences generally showed low affiliation to any known 16S rRNA gene sequences.
Upon oxidation of the polyunsaturated fatty acids in fish oil, either before ingestion or, as recently shown, during the gastro-intestinal passage, a cascade of potentially cytotoxic peroxidation products, such as malondialdehyde and 4-hydroxy-2-hexenal, can form. In this study, we digested fresh and oxidised cod liver oils in vitro, monitored the levels of lipid peroxidation products and evaluated oxidative, proteomic and inflammatory responses to the two types of digests in the yeast Saccharomyces cerevisiae and human monocyte-derived dendritic cells.
Digests of cod liver oil with 22-53 µmol L(-1) malondialdehyde and 0.26-3.7 µmol L(-1) 4-hydroxy-2-hexenal increased intracellular oxidation and cell energy metabolic activity compared to a digested blank in yeast cells and the influence of digests on mitochondrial protein expression was more pronounced for oxidised cod liver oil than fresh cod liver oil. The four differentially expressed and identified proteins were related to energy metabolism and oxidative stress response. Maturation of dendritic cells was affected in the presence of digested fresh cod liver oil compared to the digested blank, measured as lower CD86 expression. The ratio of secreted cytokines, IL-12p40/IL-10, suggested a pro-inflammatory effect of the digested oils in relation to the blank (1.47-1.67 vs. 1.07).
Gastro-intestinal digestion of cod liver oil increases the amount of oxidation products and resulting digests affect oxidation in yeast and immunomodulation of dendritic cells.
Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits.