Novel insights into hákarl: A deep dive into the microbiological and physico-chemical features of Iceland's traditional fermented shark.

Background/Objectives: Kozan Misket orange (Citrus sinensis L.) is a regional Turkish cultivar valued for its unique flavor, yet the mechanisms underlying its aroma development remain unclear. Volatile compounds are key contributors to citrus sensory quality, and β-glucosidase is involved in releasing glycosidically bound aroma precursors. However, no previous study has examined the interaction between enzyme activity and volatile production during maturation in this cultivar. This study aimed to characterize the dynamic changes in volatile composition and β-glucosidase activity across different maturation stages of Kozan Misket orange. Methods: Fruits were harvested at three maturity stages (green, green–yellow, yellow). Physicochemical traits (TSS, TA, TSS/TA), volatile profiles (HS-SPME/GC-MS), and specific β-glucosidase activity were analyzed. Volatile compounds were identified, quantified, and compared across stages. Results: A total of 47 volatile compounds were identified, with monoterpenes dominating at all stages. D-limonene was the most abundant compound, exceeding 86% of total volatiles. Total volatile content increased with maturation, particularly monoterpenes and sesquiterpenes, whereas oxygenated monoterpenes (e.g., linalool, 4-terpineol, α-terpineol) declined at full maturity. Specific β-glucosidase activity decreased markedly from 20.15 to 8.25 U mg−1 protein. This shift suggests that bound precursors contribute more to early-stage aroma release, while later-stage aroma accumulation may rely on metabolic conversions. Conclusions: This study provides the first integrated insight into aroma development in Kozan Misket orange, revealing a dual-phase mechanism linking volatile formation and β-glucosidase activity. These findings clarify cultivar-specific flavor development and offer guidance for harvest optimization and flavor management.

Volatile component profiles of raw and canned sea urchin gonads were analyzed using dynamic headspace sampling onto an adsorbent, followed by microwave desorption into a gas chromatograph equipped with a mass spectrometric detector. Thirty-nine compounds were identified, including alcohols, aldehydes, aromatic hydrocarbons, furans, hydrocarbons, ketones, nitrogen-containing compounds, sulfur-containing compounds and terpenes. The most important changes caused by sterilization were: (1) appearance of furans, nitrogen-containing compounds and branched aldehydes; (2) increase in the contents of aldehydes and sulfur-containing compounds. It is concluded that the change in aroma during canning depends on compounds from lipid oxidation and from thermal degradation of carbohydrates as well as compounds from other types of reactions, e.g. the Strecker degradation and the Maillard reaction.

Microorganisms are ubiquitous and represent a taxonomically and functionally diverse component of freshwater environments of significant ecological importance. The bacteria, archaea, and microbial eukarya in freshwater systems support a range of ecosystem processes and functions, including mediating all major biogeochemical cycles, and therefore regulate the flow of multiple ecosystem services. Yet relative to conspicuous higher taxa, microbial ecology remains poorly understood. As the anthropocene progresses, the demand for freshwater–ecosystem services is both increasing with growing human population density, and by association, increasingly threatened from multiple and often interacting stressors, such as climate change, eutrophication, and chemical pollution. Thus, it is imperative to understand the ecology of microorganisms and their functional role in freshwater ecosystems if we are to manage the future of these environments effectively. To do this, researchers have developed a vast array of molecular tools that can illuminate the diversity, composition, and activity of microbial communities. Within this primer, we discuss the history of molecular approaches in microbial ecology, and highlight the scope of questions that these methods enable researchers to address. Using some recent case studies, we describe some exemplar research into the microbial ecology of freshwater systems, and emphasize how molecular methods can provide novel ecological insights. Finally, we detail some promising developments within this research field, and how these might shape the future research landscape of freshwater microbial ecology.This article is categorized under: Water and Life > Methods Water and Life > Nature of Freshwater Ecosystems

Long-term ditch-buried straw return increases functionality of soil microbial communities

Microorganisms make plastic degradable, without additives

The abundance, diversity, activity, and composition of microbial communities in sulfide structures both of active and inactive vents were investigated by culture-independent methods. These sulfide structures were collected at four hydrothermal fields, both on- and off-axis of the back-arc spreading center of the Southern Mariana Trough. The microbial abundance and activity in the samples were determined by analyzing total organic content, enzymatic activity, and copy number of the 16S rRNA gene. To assess the diversity and composition of the microbial communities, 16S rRNA gene clone libraries including bacterial and archaeal phylotypes were constructed from the sulfide structures. Despite the differences in the geological settings among the sampling points, phylotypes related to the Epsilonproteobacteria and cultured hyperthermophilic archaea were abundant in the libraries from the samples of active vents. In contrast, the relative abundance of these phylotypes was extremely low in the libraries from the samples of inactive vents. These results suggest that the composition of microbial communities within sulfide structures dramatically changes depending on the degree of hydrothermal activity, which was supported by statistical analyses. Comparative analyses suggest that the abundance, activity and diversity of microbial communities within sulfide structures of inactive vents are likely to be comparable to or higher than those in active vent structures, even though the microbial community composition is different between these two types of vents. The microbial community compositions in the sulfide structures of inactive vents were similar to those in seafloor basaltic rocks rather than those in marine sediments or the sulfide structures of active vents, suggesting that the microbial community compositions on the seafloor may be constrained by the available energy sources. Our findings provide helpful information for understanding the biogeography, biodiversity and microbial ecosystems in marine environments.

Microbial ecology examines the diversity and activity of micro-organisms in Earth's biosphere. In the last 20 years, the application of genomics tools have revolutionized microbial ecological studies and drastically expanded our view on the previously underappreciated microbial world. This review first introduces the basic concepts in microbial ecology and the main genomics methods that have been used to examine natural microbial populations and communities. In the ensuing three specific sections, the applications of the genomics in microbial ecological research are highlighted. The first describes the widespread application of multilocus sequence typing and representational difference analysis in studying genetic variation within microbial species. Such investigations have identified that migration, horizontal gene transfer and recombination are common in natural microbial populations and that microbial strains can be highly variable in genome size and gene content. The second section highlights and summarizes the use of four specific genomics methods (phylogenetic analysis of ribosomal RNA, DNA-DNA re-association kinetics, metagenomics, and micro-arrays) in analysing the diversity and potential activity of microbial populations and communities from a variety of terrestrial and aquatic environments. Such analyses have identified many unexpected phylogenetic lineages in viruses, bacteria, archaea, and microbial eukaryotes. Functional analyses of environmental DNA also revealed highly prevalent, but previously unknown, metabolic processes in natural microbial communities. In the third section, the ecological implications of sequenced microbial genomes are briefly discussed. Comparative analyses of prokaryotic genomic sequences suggest the importance of ecology in determining microbial genome size and gene content. The significant variability in genome size and gene content among strains and species of prokaryotes indicate the highly fluid nature of prokaryotic genomes, a result consistent with those from multilocus sequence typing and representational difference analyses. The integration of various levels of ecological analyses coupled to the application and further development of high throughput technologies are accelerating the pace of discovery in microbial ecology.

The diversity and succession of microbial community and antioxidant activity present during the preparation of red raspberry Enzymes with and without starter cultures were investigated by high‐throughput sequencing of 16S rRNA and ITS1 genes and correlation analysis of the microbial diversity and antioxidant activity. The results showed that the sample inoculated with mixed fermentation had higher antioxidant activity than the sample without inoculated fermentation. The antioxidant capacity of red raspberry Enzymes increased significantly as the fermentation time increased. Firmicutes and Ascomycota were the predominant phyla of bacteria and fungi in all samples. At the genus level, Rhodococcus and Lactobacillus were the predominating bacteria throughout the fermentation process. The genus Kodamaea dominated the fungal community of early‐fermentation samples with microbial inoculated fermentation. Candida spp. grew rapidly in the late stage of fermentation in the samples with spontaneous fermentation. Unweighted pair‐group and PCA analysis revealed that the microbiota structures differed between the two groups. RDA and CCA showed that Rhodococcus and Kodamaea had positive effects on the DPPH scavenging ability and other antioxidant indicators, and the total phenol content had a significant and positive correlation coefficient with Gluconobacter. The results indicated that the fermentation by microorganisms significantly improves the oxidation resistance and helps to improve the quality of the red raspberry Enzymes.

The use of Delta 6 desaturase (D6D) twice in the conversion of alpha-linolenic acid (ALA; 18:3n-3) to docosahexaenoic acid (DHA; 22:6n-3) suggests that this enzyme may play a key regulatory role in the synthesis and accumulation of DHA from ALA. We examined this using an in vitro model of fatty acid metabolism to measure the accumulation of the long-chain metabolites of ALA in HepG2 cell phospholipids. The accumulation of ALA, eicosapentaenoic acid (20:5n-3), docosapentaenoic acid (22:5n-3), and 24:5n-3 in cell phospholipids was linearly related to the concentration of supplemented ALA over the range tested (1.8-72 microM). The accumulation of the post-D6D products of 22:5n-3, 24:6n-3 and DHA, in cell phospholipids was saturated at concentrations of >18 microM ALA. Supplementation of HepG2 cells with preformed DHA revealed that, although the accumulation of DHA in cell phospholipids approached saturation, the level of DHA in cell phospholipids was significantly greater compared with the accumulation of DHA from ALA, indicating that the accumulation of DHA from ALA was not limited by incorporation. The parallel pattern of accumulation of 24:6n-3 and DHA in response to increasing concentrations of ALA suggests that the competition between 24:5n-3 and ALA for D6D may contribute to the limited accumulation of DHA in cell membranes.

Tianzao is a traditional fermented food with significant cultural and economic value in China with few studies for the storage cycle. This study explores the microbial community dynamics and metabolites of Tianzao during different storage periods. Tianzao samples stored continuously for months of 3 (T1), 6 (T2), 12 (T3), and 18 (T4) were analyzed mainly through illumina sequencing, GC-IMS (Gas Chromatography-Ion Mobility Spectrometry), and LC-MS (Liquid Chromatography-Mass Spectrometry). The results showed the microbial community structure of Tianzao changed significantly over time. Bacillus had the most abundance among bacterial genus, with the highest percentage in T3. Prevotella was most abundant in T4. Fungal Saccharomycopsis was the most prevalent in T1, T2, and T3. While Aspergillus dominated in T4. For microbial community structure, stochastic processes predominated, with drift being the most significant contributor. Metabolomic analysis showed amino acids were the highest abundance. Temporal analysis revealed significant shifts in metabolic pathways, with distinct metabolite profiles with each stage. GC-IMS highlights the differences in volatile profiles among four stages based on several aspects including fingerprint and PCA (Principal Component Analysis). Correlation analysis demonstrated that microbial community changes were significantly linked to variations in metabolite levels and volatile compounds. The dominant microbial groups, particularly Bacillus and Saccharomycopsis, were closely associated with key flavor compounds. The study shows a integrated overview of the microbial and metabolic dynamics during Tianzao storage, offering insights into improving product quality control.

Tidal wetland reclamation is a worldwide issue that profoundly alters ecological functions and ecosystem service provisions; however, its impacts on sediment microbial communities and functions remain poorly understood. Here, we investigated the spatial and seasonal patterns of greenhouse gas (GHG) production in response to land use change in mangrove wetlands and elucidated the underlying mechanisms by integrating environmental parameters and microbial community characteristics. In the time period studied, land use change substantially reduced the sediment organic matter content, microbial community richness and diversity, and CO 2 production rates. Converting mangroves to drier land cover types, namely orchard and vegetable field, significantly diminished reducing substrates (sulfide, Fe 2+ , and NH 4 + ), microbial network complexity and stability, and CH 4 production rates, while increasing N 2 O production rates. In contrast, these parameters showed the opposite trend following the conversion of mangroves to flooded aquaculture pond. Overall GHG production rate in mangrove wetlands was 399.8 mg CO 2 e kg −1 d −1 , which respectively decreased by 68.83%, 69.86%, and 30.84% in orchard, vegetable field, and aquaculture pond. Microbial community richness and network complexity and stability were strongly related to the production rates of CH 4 and N 2 O, rather than CO 2 , which can be better indicators of specialized functions (CH 4 and N 2 O production). Therefore, preserving microbial “interaction” could be important to mitigate the negative effects of microbial community richness and diversity loss caused by human activities in aquatic environments. Future research should consider environmental conditions and microbial community diversity, composition, interactions, and activities to gain a comprehensive understanding of ecosystem functions.

Elevated levels of Total Cholesterol (TC), low-density lipoprotein (LDL) and triglycerides (TG) during pregnancy have been associated with risks of gestational diabetes, preeclampsia, fetal macrosomia and cardiovascular disease. Exercise is known to decrease TC, LDL and TG, while increasing HDL within normal ranges. Similarly, Supplementation of polyunsaturated fatty acids (PUFA), such as DHA, help control and mitigate excessive triglycerides, while increasing HDL. Research has not investigated the potential relationship of maternal exercise and PUFA levels on maternal lipid profiles. PURPOSE: To determine the relationship between maternal exercise and plasma levels of DHA on maternal lipid levels at 16 and 36 weeks. METHODS: 22 women with a singleton pregnancy (<16 weeks) were randomized to either aerobic (n=9) or non-exercising control (n=4) group. Participants exercised 3x50 minutes per week at moderate intensity for ~24 weeks, with average weekly METmins/wk calculated based on standard MET values*average minutes. Maternal plasma was collected at 16 and 36 weeks of gestation and analyzed for DHA and lipid levels. Multiple linear regression and Spearman correlation models were performed to determine relationships between maternal METmins/wk, DHA levels, and lipid levels. RESULTS: There is a significant negative correlation between DHA levels on HDL (-0.692, p=0.01) at 36 weeks. There are trends of significance with METmins/wk with DHA (0.500; p=0.08) and TG (-0.440, p=0.13) at 36 wks. There was not a significant regression equation found for TC (F=0.690, p=0.52) and TG (F=2.092, p=0.174), however METmins/wk showed a negative relationship to TC (-0.094, p=0.307) and trended to significantly predict TG (-0.185, p=0.081) while DHA Levels showed a positive relationship with TC (0.059, p=0.331) and TG (0.105, p=0.125). CONCLUSION: The current suggests a potential relationship between exercise and DHA levels during pregnancy on maternal lipids. These findings showed a negative and stronger relationship with METmins/wk compared to DHA levels, thus suggesting exercise may be more important to control excessive increases in TC and TG during pregnancy.

In a majority of the solar/thermal studies to date, a utility economic methodology has been used to assess the potential of solar power systems. The utility sector is precluded from taking advantage of loan leveraging because the effective rate of return is artificially set. Utilities are regulated by public commissions and thus must finance new capital investments according to a prescribed set of rules on after tax cost of capital and fixed charge rates. Commercial ventures have no such externally imposed constraints and make decisions for capital expenditures which include the effect of loan leveraging. The relevant parameters for a commercial institution are interest rate on debt, a discount rate which accounts for risk, and the effect of favorable tax incentives. An expression is developed for a capital cost factor which contains these parameters. Results are shown for various downpayments and discount rates. It will be shown that the effect of loan leveraging can be substantial in affecting the penetration of solar process heat into the commercial energy market. In addition, the relation between loan leveraging and risk is investigated.

Microbial Ecology and Process Technology of Sourdough Fermentation.

Comparison of fertility and seasonal effects on grassland microbial communities