Lipid deterioration of two lean fish species, saithe (Pollachius virens) and hoki (Macruronus novaezelandiae), during frozen storage at −20 and −30 ° C (up to 18 months) was studied. Lipid composition, lipid oxidation and hydrolysis, and sensory attributes were evaluated on both light and dark muscles of the fish species. Results showed significant lipid deterioration with extended storage time, but lower storage temperature showed significantly more preservative effects. A marked difference was observed between the composition of dark muscle of hoki and saithe. Polyunsaturated fatty acids were the predominant lipids in dark muscle of saithe, while monounsaturated fatty acids were predominant in dark muscle of hoki. Further, the hydrolytic activity differed greatly between dark muscle of hoki and saithe, with significantly lower activity observed in hoki. Present results indicate that both tertiary lipid oxidation and hydrolysis products are appropriate for assessing lipid deterioration of saithe and hoki light muscle during frozen storage.
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Near infrared spectroscopy (NIR) was applied to estimate lipid composition and degradation of two lean fish species, saithe (Pollachius virens) and hoki (Macruronus novaezelandiae). Calibration models were developed, using partial least squares (PLS) regression, for total lipid content and composition, free fatty acids (FFA), thiobarbituric acid reactive substances (TBARS) and fluorescent interaction compounds (OFR). Coefficients of determination for calibration (R2cv) and root-mean-square error of cross validation (RMSECV) ranged from 0.82 to 0.99 and 0.66 to 3.69 for hoki and from 0.64 to 0.99 and 0.06 to 2.65 for saithe, respectively. The validations of the calibrations indicated that lipid composition and FFA of hoki and saithe can be estimated by NIR with good accuracy. Furthermore, NIR differentiates fish muscles with low, medium and high concentration of OFR and TBARS. Overall, the results demonstrate the potential for use of NIR spectroscopy as an objective and non-destructive method to inspect the lipid characteristics and quality of frozen lean fish.
As the ice cap of the Arctic diminishes due to global warming, the polar sailing route will be open larger parts of the year. These changes are likely to increase the pollution load on the pristine Arctic due to large vessel traffic from specific contaminant groups, such as polycyclic aromatic hydrocarbons (PAHs). A well-documented baseline for PAH concentrations in the biota in the remote regions of the Nordic Seas and the sub-Arctic is currently limited, but will be vital in order to assess future changes in PAH contamination in the region. Blue mussels (Mytilus edulis) were collected from remote sites in Greenland, Iceland, the Faroe Islands, Norway and Sweden as well as from urban sites in the same countries for comparison. Code (Gadus morhua) was caught north of Iceland and along the Norwegian coast. Sixteen priority PAH congeners and the inorganic trace elements arsenic, cadmium, mercury and lead were analyzed in the blue mussel samples as well as PAH metabolites in cod bile. Σ16PAHs ranged from 28 ng/g dry weight (dw) (Álftafjörður, NW Iceland) to 480 ng/g dw (Ísafjörður, NW Iceland). Mussel samples from Mjóifjörður, East Iceland and Maarmorilik, West Greenland, contained elevated levels of Σ16PAHs, 370 and 280 ng/g dw, respectively. Levels of inorganic trace elements varied with highest levels of arsenic in mussels from Ísafjörður, Iceland (79 ng/g dw), cadmium in mussels from Mjóifjörður, Iceland (4.3 ng/g dw), mercury in mussels from Sørenfjorden, Norway (0.23 ng /g dw) and lead in mussels from Maarmorilik, Greenland (21 ng/g dw). 1-OH-pyrene was only found above limits of quantification (0.5 ng/mL) in samples from the Norwegian coast, ranging between 44 and 140 ng/ml bile. Generally, PAH levels were low in mussels from the remote sites investigated in the study, which indicates a limited current effect on the environment.
The co-authors of this paper hereby state their intention to work together to launch the Genomic Observatories Network (GOs Network) for which this document will serve as its Founding Charter. We define a Genomic Observatory as an ecosystem and / or site subject to long-term scientific research, including (but not limited to) the sustained study of genomic biodiversity from single-celled microbes to multicellular organisms.
An international group of 64 scientists first published the call for a global network of Genomic Observatories in January 2012. The vision for such a network was expanded in a subsequent paper and developed over a series of meetings in Bremen (Germany), Shenzhen (China) , Moorea (French Polynesia), Oxford (UK), Pacific Grove (California, USA), Washington (DC, USA), and London (UK). While this community-building process continues, here we express our mutual intent to establish the GOs Network formally, and to describe our shared vision for its future. The views expressed here are ours alone as individual scientists, and do not necessarily represent those of the institutions with which we are affiliated.
The aim was to develop a Quality Index Method (QIM) scheme for fresh tilapia fillets and evaluate the scheme in a shelf life study. Farmed tilapia fillets were stored at 1 and −1 ° C for up to 20 days, and changes during storage were observed with sensory evaluation using the QIM scheme and General Descriptive Analysis (GDA), total viable counts (TVC), and hydrogen sulphide ( H2S) producing bacteria. The maximum shelf life of fillets stored at1 and −1 ° C was determined with GDA and microbial counts as 16 and 19 days, respectively. A high correlation of R2 = 0.943 between Quality Index (QI) and storage time at 1C ° was found to be 0.843 at −1 ° C. At the end of shelf life, the QI was 5.3 and 6.5 out of a maximum score of 15 for fillets stored at 1 and −1 ° C, respectively. Total viable counts and H2S-producing bacteria showed an increasing trend during storage time for both groups. At the end of shelf life, TVC was log 7 cfu / g in the flesh of both groups, with H2S producing bacteria constituting a higher proportion (log 6 cfu / g) of the total. The scheme was modified at the end of the study to better characterize deskinned farmed tilapia fillets.
An alkali-extractable O-methylated ribofuranose-containing heteroglycan, Nc-5-s, was isolated from wild-growing field colonies of the cyanobacterium Nostoc commune collected in Iceland, using ethanol fractionation and anion-exchange chromatography. The average molecular weight was estimated to be 1500 kDa. Structural characterization of the heteroglycan was performed by high-field NMR spectroscopy (1D proton, 2D-COSY, 2D-NOESY, 2D-TOCSY, 1H 13C-HSQC, HMBC, H2BC and HSQC-NOESY) as well as monosaccharide analysis after methanolysis by GC and supported by linkage analysis by GC – MS.
Existence of life in extreme environments has been known for a long time, and their habitants have been investigated by different scientific disciplines for decades. However, reports of multidisciplinary research are uncommon. In this paper, we report an interdisciplinary three-day field campaign conducted in the framework of the Coordination Action for Research Activities on Life in Extreme Environments (CAREX) FP7EU program, with participation of experts in the fields of life and earth sciences. In situ experiments and sampling were performed in a 20 m long hot springs system of different temperature (57 ° C to 100 ° C) and pH (2 to 4). Abiotic factors were measured to study their influence on the diversity. The CO2 and H2S concentration varied at different sampling locations in the system, but the SO2 remained the same. Four biofilms, mainly composed of four different algae and phototrophic protists, showed differences in photosynthetic activity. Varying temperature of the sampling location affects chlorophyll fluorescence, not only in the microbial mats, but plants (Juncus), indicating selective adaptation to the environmental conditions. Quantitative polymerase chain reaction (PCR), DNA microarray and denaturing gradient gel electrophoresis (DGGE) -based analysis in laboratory showed the presence of a diverse microbial population. Even a short duration (30 h) deployment of a micro colonizer in this hot spring system led to colonization of microorganisms based on ribosomal intergenic spacer (RISA) analysis. Polyphasic analysis of this hot spring system was possible due to the involvement of multidisciplinary approaches.
Subglacial lakes beneath the Vatnajökull ice cap in Iceland host endemic communities of microorganisms adapted to cold, dark and nutrient-poor waters, but the mechanisms by which these microbes disseminate under the ice and colonize these lakes are unknown. We present new data on this subglacial microbiome generated from samples of two subglacial lakes, a subglacial flood and a lake that was formerly subglacial but now partially exposed to the atmosphere. These data include parallel 16S rRNA gene amplicon libraries constructed using novel primers that span the v3–v5 and v4–v6 hypervariable regions. Archaea were not detected in either subglacial lake, and the communities are dominated by only five bacterial taxa. Our paired libraries are highly concordant for the most abundant taxa, but estimates of diversity (abundance-based coverage estimator) in the v4–v6 libraries are 3–8 times higher than in corresponding v3–v5 libraries. The dominant taxa are closely related to cultivated anaerobes and microaerobes, and may occupy unique metabolic niches in a chemoautolithotrophic ecosystem. The populations of the major taxa in the subglacial lakes are indistinguishable (>99% sequence identity), despite separation by 6 km and an ice divide; one taxon is ubiquitous in our Vatnajökull samples. We propose that the glacial bed is connected through an aquifer in the underlying permeable basalt, and these subglacial lakes are colonized from a deeper, subterranean microbiome.
Natural thermal bathing pools contain geothermal water that is very popular to bathe in but the water is not sterilized, irradiated or treated in any way. Increasing tourism in Iceland will lead to increasing numbers of bath guests, which can in turn affect the microbial flora in the pools and therefore user safety. Today, there is no legislation that applies to natural geothermal pools in Iceland, as the water is not used for consumption and the pools are not defined as public swimming pools. In this study, we conducted a microbiological analysis on three popular but different natural pools in Iceland, located at Lýsuhóll, Hveravellir and Landmannalaugar. Total bacterial counts were performed by flow cytometry, and with plate count at 22 ° C, 37 ° C and 50 ° C. The presence of viable coliforms, Enterococcus spp. and pseudomonads were investigated by growth experiments on selective media. All samples were screened for noroviruses by real time PCR. The results indicate higher fecal contamination in the geothermal pools where the geothermal water flow was low and bathing guest count was high during the day. The number of cultivated Pseudomonas spp. was high (13,000–40,000 cfu / 100 mL) in the natural pools, and several strains were isolated and classified as opportunistic pathogens. Norovirus was not detected in the three pools. DNA was extracted from one-liter samples in each pool and analyzed by partial 16S rRNA gene sequencing. Microbial diversity analysis revealed different microbial communities between the pools and they were primarily composed of alpha-, beta- and gammaproteobacteria.
A convenience ready-to-reconstitute cutlet mix containing 30% fish protein powder was developed to improve the nutritional quality of the product. Consumer survey was based on the home use test (HUT) method. The acceptance of the fish cutlet mix (FCM) was studied using a 9-point hedonic scale ranging from 1 (extremely dislike) to 9 (extremely like). Product's characteristics and stability were studied during 6 months of storage at 27 ± 2 ° C. The FCM packed in a polyethylene bag and cardboard box was stable during the storage period. There were no changes in color, moisture gain and water activity, and TBARS values remained low. The FCM was accepted by the consumers in the study (n = 85). The average liking was high (7.5 ± 1.3) and it was influenced by frequency of fish and chicken consumption, educational level and household size. People who ate fish once a week liked the product more than other consumers. Also those with higher educational level and bigger household size. The results in this paper are important information for companies planning to develop ready-to-eat products fortified with fish proteins. The products could be means of increasing fish consumption in countries / areas where there is no tradition of consuming fresh or frozen fish.