Author: admin

Contact

Hildur Inga Sveinsdóttir

Project Manager

hilduringa@matis.is

To ensure year-round availability and stability of Atlantic mackerel caught in Icelandic waters during summer after intensive feeding, freezing is essential. Due to the high lipid content and sensitive lipid composition of the fish caught at this time, the fish industry requires detailed research to understand the mechanisms underlying the degradation processes occurring during storage and processing, in order to develop high-value hot-smoked products. Therefore, the impact of frozen storage at -25 ± 1.8 °C (for 6, 9, and 20 months) prior to hot-smoking, was investigated on the physicochemical, microbial, and sensory quality of deep-skinned, smoked fillets from well -fed Atlantic mackerel caught in late August. The stability of hot-smoked fillets stored at 1 ± 0.6 °C was then monitored for 28 days. Total aerobic viable counts (TVC) remained below acceptable thresholds due to the combined effects of brining, freezing, and hot-smoking, while Listeria monocytogenes was not detected in the hot-smoked products. Slow formation of oxidation products was observed during the chilled storage, especially in the fish frozen for 9 months. Minor lipid deterioration was also detected during sensory analysis, but all spoilage indices remained within acceptable thresholds for shelf-life. Frozen storage for up to 20 months thus effectively maintains the sensory acceptability and suitability of deep-skinned mackerel fillets, making them an excellent choice for the fish-smoking industry.

Photosymbiodemes are a special case of lichen symbiosis where one lichenized fungus engages in symbiosis with two different photosynthetic partners, a cyanobacterium and a green alga, to develop two distinctly looking photomorphs. We compared gene expression of thallus sectors of the photosymbiodeme-forming lichen Peltigera britannica containing cyanobacterial photobionts with thallus sectors with both green algal and cyanobacterial photobionts and investigated differential gene expression at different temperatures representing mild and putatively stressful conditions. First, we quantified photobiont-mediated differences in fungal gene expression. Second, because of known ecological differences between photomorphs, we investigated symbiont-specific responses in gene expression to temperature increases. Photobiont-mediated differences in fungal gene expression could be identified, with upregulation of distinct biological processes in the different morphs, showing that interaction with specific symbiosis partners profoundly impacts fungal gene expression. Furthermore, high temperatures expectedly led to an upregulation of genes involved in heat shock responses in all organisms in whole transcriptome data and to an increased expression of genes involved in photosynthesis in both photobiont types at 15 and 25°C. The fungus and the cyanobacteria exhibited thermal stress responses already at 15°C, the green algae mainly at 25°C, demonstrating symbiont-specific responses to environmental cues and symbiont-specific ecological optima.

Link to article.

Contact

Ásta Heiðrún E. Pétursdóttir

Project Manager

asta.h.petursdottir@matis.is

Results: In general, lower levels of total As were detected in the samples collected in May (39.2–74.5 mg kg⁻¹) compared to those collected in February (72.6–151 mg kg⁻¹). The concentration of arsenate was found to consistently increase along the thallus from the holdfast/stipe (0.78–1.82 mg kg⁻¹) to the decaying fronds (44.4–61.0 mg kg⁻¹) in both months, and AsSug-SO₃ was the dominant AsSugar in the majority of samples. The extraction efficiency was lower in fresh samples (64–77%) than in freeze-dried (95–116%) from the same month. Water-soluble, polar AsLipids, and residual As concentrations, were generally highest in February, and the non-polar AsLipids accounted for <0.42% of totAs in all samples.

Contact

Sæmundur Sveinsson

Research Group Leader

saemundurs@matis.is

In recent years the number of non-indigenous marine species has been increasing in Icelandic waters. In May 2019, a razor shell (Ensis sp.) was found for the first time in Iceland. Since then, living and empty razor shells have been discovered at several locations in Southwest Iceland. Upon morphological examination, the specimens were thought to belong to either Ensis leei or Ensis terranovensis, both native to the east coast of North America. Molecular analysis, using COI and 16S rRNA markers,
showed that the Icelandic specimens belong to the latter species. Native populations of Ensis terranovensis have, until now, only been reported in Newfoundland, Canada. This represents the first record of E. terranovensis outside its native range. The Newfoundland's razor shell has most likely arrived in Iceland as larvae discharged with ballast water. Based on the sizes of specimens found in Iceland, the species is likely to have arrived several years prior to this first record. Presumably it has already established viable spawning populations that are likely to spread along the coast

Contact

Davíð Gíslason

Project Manager

davidg@matis.is

Aquaculture of the lumpfish (Cyclopterus lumpus L.) has become a large, lucrative industry owing to the escalating demand for "cleaner fish" to minimize sea lice infestations in Atlantic salmon mariculture farms. We used over 10K genome-wide single nucleotide polymorphisms (SNPs) to investigate the spatial patterns of genomic variation in the lumpfish along the coast of Norway and across the North Atlantic. Moreover, we applied three genome scans for outliers and two genotype–environment association tests to assess the signatures and patterns of local adaptation under extensive gene flow. With our 'global' sampling regime, we found two major genetic groups of lumpfish, ie, the western and eastern Atlantic. Regionally in Norway, we found marginal evidence of population structure, where the population genomic analysis revealed a small portion of individuals with a different genetic ancestry. Nevertheless, we found strong support for local adaptation under high gene flow in the Norwegian lumpfish and identified over 380 high-confidence environment-associated loci linked to gene sets with a key role in biological processes associated with environmental pressures and embryonic development. Our results bridge population genetic/genomics studies with seascape genomics studies and will facilitate genome-enabled monitoring of the genetic impacts of escapees and allow for genetically-informed broodstock selection and management in Norway.

Contact

Elísabet Eik Guðmundsdóttir

Project Manager

elisabet@matis.is

Production of fish meal and plant-based feed proteins continues to increase to meet the growing demand for seafood, leading to impacts on marine and terrestrial ecosystems. Microbial proteins such as single-cell proteins (SCPs) have been introduced as feed alternatives since they can replace current fish feed ingredients, eg, soybean, which are associated with negative environmental impacts. Microbial protein production also enables utilization of grain processing side-streams as feedstock sources. This study assesses the environmental impacts of yeast-based SCP using oat side-stream as feedstock (OS-SCP). Life-cycle assessment with a cradle-to-gate approach was used to quantify global warming, freshwater eutrophication, marine eutrophication, terrestrial acidification, land use, and water consumption of OS-SCP production in Finland. Dried and wet side-streams of oat were compared with each other to identify differences in energy consumption and transportation effects. Sensitivity analysis was performed to examine the difference in impacts at various locations and fermentation times. Benchmarking was used to evaluate the environmental impacts of OS-SCP and other feed products, including both conventional and novel protein products. Results highlight the importance of energy sources in quantifying the environmental performance of OS-SCP production. OS-SCP produced with dried side-streams resulted in higher global warming (16.3 %) and water consumption (7.5 %) than OS-SCP produced from wet side-streams, reflecting the energy and water requirements for the drying process. Compared with conventional products, such as soy protein concentrates, OS-SCP resulted in 61 % less land use, while exacerbating the environmental impacts in all the other categories. OS-SCP had more impact on global warming (205–754 %), water consumption (166–1401 %), freshwater eutrophication (118–333 %), and terrestrial acidification (85–340 %) than other novel products, including yeast protein concentrate, methanotrophic bacterial SCP, and insect meal, while lowering global warming (11 %) and freshwater eutrophication (20 %) compared with dry microalgae biomass.