Current status of research on golden pomfret processing and high⁃value utilization of by⁃products

Trachinotus ovatus is one of the main marine economic fish species in the South China sea, which is delicious and with high nutritional value. With the rapid development of culture technology, the output of golden pomfret is increasing in recent years. Its healthy circulation, fresh preservation and deep processing are of great significance to the healthy and sustainable development of the industry. This review summarized the current status of comprehensive processing and utilization technology of T. ovatus, including keep alive technology, low temperature preservation technology, non thermal processing technology, surimi processing technology, canning technology, pickling and smoking processing technology, and high value processing products of golden pomfret protein, prepared food, and high⁃value utilization of by⁃products (fish head, fish bone, visceral protease, fish oil, and collagen). The shortcoming of all aspects and the direction of future development are also discussed

Whole genome sequencing of a novel carrageenan-degrading bacterium Photobacterium rosenbergii and oligosaccharide preparation

IntroductionCarrageenan oligosaccharides are of significant interest due to their diverse bioactivities, necessitating efficient methods for their production. To this day, the discovery and isolation of microorganisms capable of effectively degrading carrageenan is still crucial for the production of carrageenan oligosaccharides. In addition, there are no current reports of bacteria of the genus Photobacterium capable of secreting κ-carrageenanase or degrading carrageenan.MethodsIn the current study, strain GDSX-4 was obtained from Gracilaria coronopifolia after enrichment culture, primary screening and rescreening and was initially characterized by morphology and 16SrDNA. The pure culture of strain GDSX-4 was further subjected to bacterial genome sequencing assembly and bioinformatic analysis. Specifically, homology group cluster (COG) annotation, CAZy (carbohydrate-active enzyme) database annotation and CAZyme genome clusters (CGCs) annotation were utilized to identify potential polysaccharide degradation functions. Enzymatic activity was assessed under different conditions, including substrate, temperature, pH, and the presence of metal ions. Hydrolysis products were analyzed using thin-layer chromatography (TLC) and electrospray ionization mass spectrometry (ESI-MS).ResultsPhotobacterium rosenbergii GDSX-4 is a Gram-negative bacterium isolated from the red algae, capable of degrading several polysaccharides. The draft genome was predicted to have 6,407,375 bp, 47.55% G+C content and 6,749 genes. Among them, 214 genes encoding carbohydrate enzymes were annotated, including carrageenase, agarose, alginate lyase, and chitinase. GDSX-4 exhibited remarkable carrageenan-degrading activity, with a specific enzyme activity of 46.94 U/mg. Optimal hydrolysis conditions were determined to be 40°C and pH 7.0, with the enzyme retaining 80% of its activity below 30°C and across a pH range of 4.0–10.0. Metal ions such as as K+, Na+, and Ba2+ enhanced enzymatic activity, while Ni2+, Mn2+, and Cu2+ had inhibitory effects. kappa-carrageenan was totally hydrolyzed into oligosaccharides with degrees of polymerization ranging from 2 to 6.DiscussionThese findings highlight the potential of GDSX-4 for the efficient production of carrageenan oligosaccharides, paving the way for applications in the food and agricultural industries. Future studies may focus on the efficient expression of κ-carrageenase and expand its industrial application in the preparation of oligosaccharides

Exploring potential polysaccharide utilization loci involved in the degradation of typical marine seaweed polysaccharides by Bacteroides thetaiotaomicron

IntroductionResearch on the mechanism of marine polysaccharide utilization by Bacteroides thetaiotaomicron has drawn substantial attention in recent years. Derived from marine algae, the marine algae polysaccharides could serve as prebiotics to facilitate intestinal microecological balance and alleviate colonic diseases. Bacteroides thetaiotaomicron, considered the most efficient degrader of polysaccharides, relates to its capacity to degrade an extensive spectrum of complex polysaccharides. Polysaccharide utilization loci (PULs), a specialized organization of a collection of genes-encoded enzymes engaged in the breakdown and utilization of polysaccharides, make it possible for Bacteroides thetaiotaomicron to metabolize various polysaccharides. However, there is still a paucity of comprehensive studies on the procedure of polysaccharide degradation by Bacteroides thetaiotaomicron.MethodsIn the current study, the degradation of four kinds of marine algae polysaccharides, including sodium alginate, fucoidan, laminarin, and Pyropia haitanensis polysaccharides, and the underlying mechanism by Bacteroides thetaiotaomicron G4 were investigated. Pure culture of Bacteroides thetaiotaomicron G4 in a substrate supplemented with these polysaccharides were performed. The change of OD600, total carbohydrate contents, and molecular weight during this fermentation were determined. Genomic sequencing and bioinformatic analysis were further performed to elucidate the mechanisms involved. Specifically, Gene Ontology (GO) annotation, Clusters of Orthologous Groups (COG) annotation, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were utilized to identify potential target genes and pathways.ResultsUnderlying target genes and pathways were recognized by employing bioinformatic analysis. Several PULs were found that are anticipated to participate in the breakdown of these four polysaccharides. These findings may help to understand the interactions between these marine seaweed polysaccharides and gut microorganisms.DiscussionThe elucidation of polysaccharide degradation mechanisms by Bacteroides thetaiotaomicron provides valuable insights into the utilization of marine polysaccharides as prebiotics and their potential impact on gut health. Further studies are warranted to explore the specific roles of individual PULs and their contributions to polysaccharide metabolism in the gut microbiota

Physicochemical Properties, Structural Characterization, Immunoenhancing and Hypoglycemic Activities of Fucoidan Extracts from Two Sargassums Species

In this study, the chemical compositions, structures, immunomodulatory and hypoglycemic activities of fucoidans from Sargassum zhangii (SZ-Fuc) and Sargassum hemiphylla (SH-Fuc) were analyzed and compared. The results showed that the sulfate group content and molecular mass of SZ-Fuc were (29.74 ± 0.01)% and 111.28 kDa, respectively, and SZ-Fuc had a relatively loose surface structure. The main chain of SZ-Fuc was composed of (→1) linked fucose, xylose, glucose, mannose and galactose, (1→3)- and (1→4)- linked xylose, (1→2)-linked mannose, (1→3)-, (1→4)- and (1→6)-linked galactose, and (1→4)- and (1→6)-linked glucose. Meanwhile, the sulfate group content and molecular mass of SH-Fuc were (44.11 ± 0.01)% and 1 166.48 kDa, respectively, SH-Fuc had a compact surface structure, and its main chain contained (→1), (1→3)- and (1→4)-linked fucose, (→1), (1→4)- and (1→6)-linked glucose, (→1) and (1→2)-linked mannose, and (1→4)-linked galactose. Besides, both SZ-Fuc and SH-Fuc had branched structures. They significantly increased NO release from RAW264.7 cells and improved the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), indicating good immunomodulatory activity. The immunomodulatory activity of SZ-Fuc was better than that of SH-Fuc, while the inhibitory effect of SH-Fuc on α-glucosidase was better than that of SZ-Fuc, suggesting that SH-Fuc had better hypoglycemic potential. This study can provide a theoretical basis for polysaccharides from S. zhangii and S. hemiphylla in the development of functional and nutritional foods with immunomodulatory and blood glucose-reducing activity

Recombinant Expression of κ-Carrageenase Cgk483 from Photobacterium rosenbergii and in Vitro Lipid-lowering Activity of κ-Carrageenan Oligosaccharides Prepared Using It

This study aimed to explore the recombinant expression of κ-carrageenase Cgk483 from Photobacterium rosenbergii and its application in preparing carrageenan oligosaccharides, which were structurally characterized and evaluated for in vitro hypolipidemic effects. Through gene cloning and heterologous expression, the electrophoretically pure recombinant enzyme Cgk483 was successfully obtained, with a molecular mass of 35.89 kDa and its specific activity was 489.88 U/mg, which was approximately 10 times higher than that of the wild-type enzyme. Enzyme kinetics studies showed that the optimal reaction temperature and pH for Cgk483 were 40 ℃ and 8.0, respectively. It was stable at temperatures below 40 ℃ and within the pH range of 5.0–10.0. Fe2+, Na+, and Ba2+ were found to enhance the enzyme activity. Using the recombinant enzyme Cgk483, κ-carrageenan oligosaccharides consisting of disaccharide, tetrasaccharide and hexasaccharide were successfully prepared. Structural analysis indicated that the enzymatic hydrolysis did not disrupt the main chain but resulted in the exposure of hydroxyl and other groups, improving the solubility of κ-carrageenan oligosaccharides. In vitro hypolipidemic assay demonstrated that κ-carrageenan oligosaccharides significantly inhibited oxidized low-density lipoprotein (Ox-LDL)-induced foam cell formation in RAW264.7 macrophages, reducing lipid accumulation. This study provides a new idea for the efficient preparation of κ-carrageenan oligosaccharides for use in the prevention and treatment of atherosclerosis

Preparation Process Optimization and Flavor Characteristic Analysis of Gracilaria Salty Flavoring Based on Maillard Reaction

The development of seaweed salty flavoring could improve the utilization rate of seaweed resources and the added value of products, which was of great significance. In this study, the preparation process of Gracilaria salty flavoring was optimized by response surface method using Gracilaria flavoring base as raw material, and the taste and flavor characteristics of Gracilaria salty flavoring were analyzed by electronic tongue and electronic nose combined with solid phase microextraction-gas-chromatography-mass spectrometry (SPME-GC-MS). The results showed that the optimal process conditions for the prepration of Gracilaria salty flavoring were as follows: Reaction temperature of 126 ℃, reaction time of 39 min, xylose content of 5%, and glycine content of 2.6%, and the sensory score was higher under this condition (75.11±0.53). The results of electronic nose combined with electronic tongue showed that Maillard reaction could improve the salty and umami taste of salty flavoring, reduce its bitter taste, increase the content of sulfide and nitrogen oxide, and the umami taste of Gracilaria salty flavoring was more obvious and the bitter taste was lower. The volatile compounds of flavoring base and salty flavoring before and after the Maillard reaction were analyzed by GC-MS. The results showed that pyrazine compounds were the main volatile compounds of two kinds of salty flavoring, and the content of alkyl pyrazines in Gracilaria salty flavoring was higher. Moreover, alcohols, esters, and acids played an important role in coordinating the overall flavor of salty flavoring. This study can provide a theoretical reference for the development of seaweed salty flavoring

Zeranol Down-Regulates p53 Expression in Primary Cultured Human Breast Cancer Epithelial Cells through Epigenetic Modification

Epidemiological studies have suggested that there are many risk factors associated with breast cancer. Silencing tumor suppressor genes through epigenetic alterations play critical roles in breast cancer initiation, promotion and progression. As a growth promoter, Zeranol (Z) has been approved by the FDA and is widely used to enhance the growth of beef cattle in the United States. However, the safety of Z use as a growth promoter is still under debate. In order to provide more evidence to clarify this critical health issue, the current study investigated the effect of Z on the proliferation of primary cultured human normal and cancerous breast epithelial cells (PCHNBECs and PCHBCECs, respectively) isolated from the same patient using MTS assay, RT-PCR and Western blot analysis. We also conducted an investigation regarding the mechanisms that might be involved. Our results show that Z is more potent to stimulate PCHBCEC growth than PCHNBEC growth. The stimulatory effects of Z on PCHBCECs and PCHBCECs may be mediated by its down-regulating expression of the tumor suppressor gene p53 at the mRNA and protein levels. Further investigation showed that the expression of DNA methylatransferase 1 mRNA and protein levels is up-regulated by treatment with Z in PCHBCECs as compared to PCHNBECs, which suggests a role of Z in epigenetic modification involved in the regulation of p53 gene expression in PCHBCECs. Our experimental results imply the potentially adverse health effect of Z in breast cancer development. Further study is continuing in our laboratory

Unraveling the chemical identification and biological potential of the genus Asparagopsis: a comprehensive review

The genus Asparagopsis has garnered escalating attention in the spheres of marine biology and biotechnology due to its diverse chemical composition and promising biological capabilities. This all-encompassing review is dedicated to conducting an exhaustive inquiry into the chemical identification and biological importance of Asparagopsis species. By meticulously dissecting the array of chemical compounds found in genus Asparagopsis, encompassing polysaccharides, lipids, proteins, sterols, and bromoform. We unveil their potential utility in realms such as biomedicine, biotechnology, and the conservation of the environment. Furthermore, we delve into the bioactive attributes inherent in these compounds, encompassing effects such as antioxidative, antimicrobial, and anti-inflammatory properties, as well as their conceivable role in cancer treatments. Furthermore, this review underscores the environmental pertinence of genus Asparagopsis, particularly its capacity to mitigate climate change through the generation of compounds that alleviate greenhouse gas effects. Additionally, we delve into the economic facets of this genus, spanning from its integration into food additives to its contributions in cosmetics and sustainable agriculture. This comprehensive review furnishes a multi-faceted comprehension of Asparagopsis, illuminating its chemical diversity and biological significance, thereby paving the way for further explorations into its potential contributions across a spectrum of sectors

New Insight into Utilization of Fish By-Product Proteins and Their Skin Health Promoting Effects

In regions reliant on fisheries for livelihoods, a significant number of fish by-products are generated annually due to processing. These discarded parts contain valuable biological resources, such as proteins, fish oils, and trace elements, thus holding enormous potential for reutilization. In recent years, fish by-product proteins have been widely utilized in skincare products due to their rich collagen content, biosafety, and biocompatibility. This review summarizes the research into and applications of fish by-product proteins in skin health, including alleviating oxidative stress and skin inflammation, reducing DNA damage, mitigating melanin production, improving skin hydration, slowing skin matrix degradation, and promoting synthesis. Additionally, the possibility of improving skin health by improving the abundance of gut microbiota is also discussed. This review underscores the importance of fish by-product proteins in the fisheries, food processing, cosmetics, and biomedical industries

Preparation and Structure Characterization of High-Value Laminaria digitata Oligosaccharides

Algae-derived marine oligosaccharides have been reported to be promising bioactive compounds because of their various properties with health benefits and potential significance in numerous applications in industrial biotechnology. In this study, laminaran oligosaccharides (LOs) with varying degrees of polymerization were obtained through partial acid hydrolysis of laminaran derived from Laminaria digitata. Based on response surface methodology, the optimum LOs yield was obtained for acid hydrolysis laminaran at a hydrolysis time of 55 min, temperature of 71°C, and acid concentration of 1.00 mol/L. The size-exclusion resin Bio-Gel P-2 was considered to be a better option for LOs purification. The structure of the purified oligosaccharides was analyzed through mass spectrometry and nuclear magnetic resonance. They demonstrated the main oligosaccharide structure corresponding to the connection of glucose with β-D-Glcp-(1→3)-β-D-Glcp, which was identified as laminaribiose (DP2), laminaritriose (DP3), laminaritetrose (DP4), and laminaripentaose (DP5). LOs demonstrate excellent antioxidant activities, as evidenced from their reactions with oxidizing free radicals, 1, 1-diphenyl-2-picryl-hydrazyl, and 2, 2′-azino-bis (3-etilbenzotiazoline-6-sulfonic acid) radicals. LOs exhibited a prebiotic effect on the growth of Bifidobacterium adolescentis and Lactobacillus plantarum. Therefore, we propose the development of LOs as natural antioxidants and prebiotics in the functional food and pharmaceutical industries.</jats:p