RBC-hitchhiking PLGA nanoparticles loading ß-glucan as a delivery system to enhance in vitro and in vivo immune responses in mice.

Red blood cells (RBCs) naturally trap some bacterial pathogens in the circulation and kill them by oxidative stress. Following neutralization, the bacteria are presented to antigen-presenting cells in the spleen by the RBCs. This ability of RBCs has been harnessed to develop a system where they play a crucial role in enhancing the immune response, offering a novel approach to enhance the body's immunity. In this work, a conjugate, G-OVA, was formed by connecting ß-glucan and OVA through a disulfide bond. Poly (lactic-co-glycolic acid) (PLGA) was then employed to encapsulate G-OVA, yielding G-OVA-PLGA. Finally, the nanoparticles were adsorbed onto RBCs to develop G-OVA-PLGA@RBC. The results demonstrated that the delivery of nanoparticles by RBCs enhanced the antibody response to antigens both in vitro and in vivo. The objective of this study was to investigate the increased immune activity of G-OVA-PLGA nanoparticles facilitated by RBCs transportation and to elucidate some of its underlying mechanisms. These findings are anticipated to contribute valuable insights for the development of efficient and safe immune enhancers.

Glucosyltransferase TeGSS from Thermosynechococcus elongatus produces an α-1,2-glucan.

Here, we enzymatically produced a novel α-1,2-glucan, glucosylsucrose, that has a chemical structure significantly different from that of other glucans. This structural difference suggests its potential to modulate new physiological activities compared to known glucans. The enzyme TeGSS catalyzes the synthesis of this α-1,2-glucan from sucrose and UDP-glucose (UDPG). Using NMR spectroscopy, we elucidated the chemical structures of TeGSS-synthesized glucosylsucrose tri-, tetra-, and penta-saccharides in which the monosaccharide units are linked by α-1,2-glycosidic bonds. We also report the crystal structures of TeGSS co-crystallized with UDP and glucosylsucrose tri- and tetra-saccharides. Site-directed mutagenesis of residues in and around the TeGSS catalytic center has allowed us to propose a concerted SNi mechanism of action. Finally, we developed an enzyme-coupled reaction involving TeGSS and SuSyAc that allows production of UDPG for the synthesis of α-1,2-glucan.

ß-glucan regulates the intestinal immunity of pearl gentian grouper via the nuclear factor kappa B signaling pathway.

The preceding study observed that yeast ß-glucan supplementation enhanced intestinal health and augmented disease resistance in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀), which occurred concurrently with the activation of the nuclear factor kappa B (NFκB) signaling pathway. Thus, we hypothesized that ß-glucan improves intestinal health in grouper by modulating the NFκB pathway. Accordingly, the present study examined the effects of NFκB pathway disruption using a specific inhibitor on the intestinal health of pearl gentian grouper that had been injected with ß-glucan. The experimental groups were as follows, (1) CD group: PBS injected; (2) ßG group: ß-glucan injected at a dose of 80 mg/kg; (3) PDTC group: NFκB inhibitor PDTC injected at a dose of 30 mg/kg; (4) ßG + PDTC group: a combination of ß-glucan (80 mg/kg) and PDTC (30 mg/kg) injected together. The results demonstrated that ß-glucan-induced increases in mRNA expression levels of NFκB inhibitor α (iκbα) and p65, the degradation and phosphorylation of IκBα, and the phosphorylation of NFκB p65 were significantly inhibited following NFκB inhibition using PDTC in the intestine of grouper. The PDTC injection resulted in a significant reduction in the ß-glucan-induced increase in mucin levels. The ß-glucan-induced elevation of alkaline phosphatase (AKP) activity, component 3 (C3) content, and inflammatory factors were significantly suppressed following NFκB inhibition. The ßG + PDTC treatment resulted in a restoration of catalase (CAT) enzyme activity to the level observed in the CD treatment, while total antioxidant capacity (T-AOC) was decreased to the level of the ßG treatment. The ß-glucan-induced downregulation of caspase8 (casp8) was reversed following NFκB inhibition, as well as the mRNA levels of casp3 and casp9 being elevated to a greater extent. In conclusion, the ß-glucan-regulated intestinal immunity in grouper may be mediated by the NFκB pathway. Furthermore, the inhibitory effect of ß-glucan on apoptosis and oxidative stress may not be related to the NFκB signaling pathway.

Technological quality improvement of gluten-free dough and chapatti-making by incorporation of modified oat 1,4-ß-D-glucan.

The present study aimed to explore the contribution of untreated (UtßG) and modified oat 1,4-ß-D-glucan (OzßG) to the quality of gluten-free chapattis at varying concentrations (0, 1.5, 3, and 4.5 % labelled as M0, M1, M2 and M3 for maize chapattis and F0, F1, F2 and F3 for finger millet chapattis, respectively). The functionality of flours was significantly enhanced by the addition of UtßG and OzßG. However, OzßG incorporated flour exhibited a more pronounced influence on both functional and farinographic parameters when compared to flours with UtßG. Further, the hardness of the chapattis decreased with incorporation of OzßG and it was lowest for M2 and F2 i.e. 6.38 N and 5.27 N, respectively due to the formation of more carboxyl and hydroxyl groups, which had more affinity towards water molecules. The sensory analysis indicated that OzßG incorporated M2 and F2chapattis exhibited the highest overall acceptability. Hence, this study provides valuable insights into the utilization of UtßG and OzßG for the formulation of gluten-free chapattis with better dough characteristics and chapatti-making properties.

Evaluating the concentration dependent dual effects of ß-Glucan on cancerous skin cells and mitochondria isolated from melanoma-induced animal model.

INTRODUCTION: Melanoma is still one of the deadliest cancers whose prevalence has increased in recent decades. Today, many polysaccharides and their bioactive compounds have been of special importance in modern biotechnology. They have various biological and therapeutic properties. they can regulate and strengthen the immune system, lower blood pressure and cholesterol, and reduce bacterial and viral infections. According to studies, these compounds also have antitumor properties. we investigated the cytotoxic effects of ß-Glucan obtained from solid-state fermentation (SSF) of edible medicinal mushroom Lentinus edodes on cancerous skin cells. MATERIALS AND METHODS: The mitochondria were isolated from melanoma cells via differential centrifugation and treated with various concentrations (30, 45, 60, 90, 120, and 240 µg/ml) of ß-Glucan extract. Then, they were subjected to MTT, ROS, MMP decline, mitochondrial swelling, cytochrome c release, and flow cytometry assays. RESULTS: The results of the MTT assay showed that IC50 of ß-Glucan extract was 60 µg/ml, and it induced a selectively significant (P < 0.05) concentration-dependent decrease in the SDH activity in cancerous skin mitochondria. At higher concentrations, no such effect was observed. The ROS results also showed that 30, 45, and 60 µg/ml concentrations of ß-Glucan extract significantly increased ROS. However, no such effect was observed at higher concentrations. MMP decline and the release of cytochrome c in cancer groups mitochondria and swelling were significantly increased at 30, 45, and 60 µg/ml compared to the control group. At higher concentrations, no such effect was observed. ß-Glucan extract at 60 µg/ml concentration increased apoptosis on melanoma cells, while it had no effect on control non-tumour cells. DISCUSSION AND CONCLUSION: Based on these results, ß-Glucan extract at 30, 45, and 60 µg/ml showed a cytotoxic effect, while no such effect was observed at higher concentrations. Overall, it seems that ß-Glucan has antioxidant and free radical scavenging effects on cancer cells at higher concentrations.

Safety evaluation of the food enzyme endo-1,3(4)-ß-glucanase from the non-genetically modified Talaromyces versatilis strain PF8.

The food enzyme endo-1,3(4)-ß-glucanase (3-(1-3;1-4)-ß-d-glucan 3(4)-glucanohydrolase; EC 3.2.1.6) is produced with the non-genetically modified Talaromyces versatilis strain PF8 by Erbslöh Geisenheim AG. The food enzyme was free from viable cells of the production organism. It is intended to be used in four food manufacturing processes. Dietary exposure to the food enzyme-total organic solids (TOS) was calculated to be up to 0.110 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 2229 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure resulted in a margin of exposure of at least 20,264. A search for homology of the amino acid sequence of the food enzyme to known allergens was made and four matches with respiratory or contact allergens were found. The Panel considered that the risk of allergic reactions upon dietary exposure cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

A novel strategy to enhance inhibition of Hela cervical cancer by combining Lentinus ß-glucan and autophagic flux blockage.

Lentinus ß-D-glucan (LNT), derived from artificially cultured mushrooms of Lentinus edodes, shows an important yet incompletely understood biological functions in cancer. In this work, the chemical structure of the refined LNT comprising a ß-D-(1, 6)-branched ß-D-(1,3)-glucan was further clarified via 1D- and 2D-NMR with high resolution, and its drug resistance resulted from autophagy in human cervical cancer (CC) Hela cells besides its anti-cancer function were revealed in vitro and in vivo. In detail, LNT destroyed cellular homeostasis by significantly increasing the intracellular Ca2+ levels and promoted autophagic flux in vitro Hela cells, which was found to at least partially depend on the PI3K/Akt/mTOR-mediated pathway by up-regulating LC3-II levels and down-regulating the expression of p62, PI3K, p-Akt, and mTOR in Hela cells-transplanted BALB/c nude mice. In particular, LNT-induced autophagy led to a drug resistance against LNT-induced proliferation inhibition and apoptosis in Hela cells, and the co-treatment of autophagy inhibitors and LNT significantly enhanced the inhibition of Hela cells and tumor growth in vitro and in vivo. Therefore, the combination of LNT and autophagy inhibitors will be a novel therapeutic strategy to reduce the resistance and improve the prognosis of CC patients in the clinical.

Effect of Complexation with Different Molecular Weights of Oat ß-Glucan and Sea Buckthorn Flavonoid on the Digestion of Rice Flour.

The complex of oat ß-glucan (OBG) and flavonoids hampered the digestion of starch-based food and retarded the blood glucose response; however, its effect on gastric emptying and its relative mechanism have not been thoroughly investigated. By using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), antioxidant ability, and enzymic inhibitory tests for the characterization and in vitro semi-dynamic digestion of complexes of OBG (high and low molecular weights) and sea buckthorn flavonoids, we found that the higher molecular weight complex (FU) exhibited stronger ABTS and DPPH radical scavenging abilities and higher α-glucosidase and α-amylase inhibition rates. Mice fed with rice flour with FU addition exhibited the slowest gastric emptying and intestinal propulsion rates and blood glucose rise and had the lowest activity of digestive enzymes and levels of insulin, ghrelin, motilin (MTL), and relevant gene (ghrelin and GHSR mRNA) expression than those in the control and low-molecular-weight groups. This study provided scientific data for the development of foods with delayed gastric rate and hypoglycemic index for specific populations.

Anti-tumor and anti-metastasis of water-soluble sulfated ß-glucan derivatives from Saccharomyces cerevisiae.

Traditional fungi ß-glucan commonly possesses high molecular weight with poor water solubility, which remains significant challenge in the drug development and medical application. Water-soluble ß-glucan with high molecular weight (dHSCG) of 560 kDa, low molecular weight (dLSCG) of 60 kDa, and sulfated derivative (SCGS) with a molecular weight of 146 kDa and sulfate degree at 2.04 were obtained through well-controlled degradation and sulfated modification from Saccharomyces cerevisiae in this study. The structural characteristics were confirmed as ß-1,3/6-glucan by FT-IR and NMR spectroscopy. Carbohydrate microarrays and surface plasmon resonance revealed distinct and contrasting binding affinities between the natural ß-glucans and sulfated derivatives. SCGS exhibited strong binding to FGF and VEGF, while natural ß-glucan showed no response, suggesting its potential as a novel antitumor agent. Moreover, SCGS significantly inhibited the migration rate of the highly metastatic melanoma (B16F10) cells. The lung metastasis mouse model also demonstrated that SCGS significantly reduced and eliminated the nodules, achieving an inhibition rate of 86.7% in vivo, with a dramatic improvement in IFN-α, TNF-α, and IL-1ß levels. Through analysis of protein content and distribution in lung tissues, the anti-tumor and anti-metastasis mechanism of SCGS involves the regulation of degrading enzymes to protect extracellular matrix (ECM), as well as the reduction of angiogenic factor release. These findings provide a foundation for exploring the potential of SCGS in the development of new anti-tumor and anti-metastasis drugs and open up a new field in cancer research.

Oat ß-(1 → 3, 1 → 4)-d-glucan alleviates food allergy-induced colonic injury in mice by increasing Lachnospiraceae abundance and butyrate production.

Oat ß-(1 â†’ 3, 1 â†’ 4)-d-glucan (OBG), a linear polysaccharide primarily found in oat bran, has been demonstrated to possess immunomodulatory properties and regulate gut microbiota. This study aimed to investigate the impact of low molecular weight (Mw) OBG (155.2 kDa) on colonic injury and allergic symptoms induced by food allergy (FA), and to explore its potential mechanism. In Experiment 1, results indicated that oral OBG improved colonic inflammation and epithelial barrier, and significantly relieved allergy symptoms. Importantly, the OBG supplement altered the gut microbiota composition, particularly increasing the abundance of Lachnospiraceae and its genera, and promoted the production of short-chain fatty acids, especially butyrate. However, in Experiment 2, the gut microbial depletion eliminated these protective effects of OBG on the colon in allergic mice. Further, in Experiment 3, fecal microbiota transplantation and sterile fecal filtrate transfer directly validated the role of OBG-mediated gut microbiota and its metabolites in relieving FA and its induced colonic injury. Our findings suggest that low Mw OBG can alleviate FA-induced colonic damage by increasing Lachnospiraceae abundance and butyrate production, and provide novel insights into the health benefits and mechanisms of dietary polysaccharide intervention for FA.

Yeast polysaccharides: The environmentally friendly polysaccharides with broad application potentials.

Yeast cell wall (YCW) polysaccharides, including ß-glucans, mannans, chitins, and glycogens, can be extracted from the waste of beer industry. They are environmentally friendly, abundant, inexpensive raw materials, and have shown broad biological activities and application potentials. The exploitation of yeast polysaccharides is of great importance for environmental protection and resource utilization. This paper reviews the structural features and preparation of YCW polysaccharides. The solubility and emulsification of yeast polysaccharides and the properties of binding metal ions are presented. In addition, biological activities such as blood glucose and lipid lowering, immune regulation, antioxidant, promotion of intestinal health, and promotion of wound healing are proposed, highlighting the beneficial effects of yeast polysaccharides on human health. Through modification, the physical and chemical properties of yeast polysaccharides are changed, which emphasizes the promotion of their biological activities and properties. In addition, the food applications of yeast polysaccharides, including the food packaging film, emulsifier, thickening agent, and fat alternatives, are focused and discussed.

Linear ß-1,2-glucans trigger immune hallmarks and enhance disease resistance in plants.

Immune responses in plants are triggered by molecular patterns or elicitors, recognized by plant pattern recognition receptors. Such molecular patterns are consequence of host-pathogen interactions and the response cascade activated after their perception is known as pattern-triggered immunity (PTI). Glucans have emerged as key players in PTI, but the ability of certain glucans to stimulate defensive responses in plants remains understudied. This work focused on identifying novel glucan oligosaccharides as molecular patterns. The ability of various microorganism-derived glucans to prompt PTI responses was tested, revealing that specific microbial-derived molecules, such as short linear ß-1,2-glucans, trigger this response in plants by increasing the production of reactive oxygen species (ROS), MAP kinase phosphorylation, and differential expression of defence-related genes in Arabidopsis thaliana. Pretreatments with ß-1,2-glucan trisaccharide (B2G3) improved Arabidopsis defence against bacterial and fungal infections in a hypersusceptible genotype. The knowledge generated was then transferred to the monocotyledonous model species maize and wheat, confirming that these plants also respond to ß-1,2-glucans, with increased ROS production and improved protection against fungal infections following B2G3 pretreatments. In summary, as with other ß-glucans, plants perceive ß-1,2-glucans as warning signals and stimulate defence responses against phytopathogens.

ß-glucan combined with Envafolimab and Endostar as immune rechallenge for metastatic non-small cell lung cancer.

BACKGROUND: Immune checkpoint inhibitor rechallenge has emerged as a prominent study area in non-small cell lung cancer (NSCLC). ß-glucan was reported to reverse resistance to anti-PD-1/PD-L1 inhibitors by regulating the tumor microenvironment. In this self-initiated clinical trial (ChiCTR2100054796), NSCLC participants who have previously failed anti-PD-1 therapy received ß-glucan (500 mg, bid, d1-21), Envafolimab (300 mg, d1) and Endostar (210 mg, civ72h) every 3 weeks until disease progression or unacceptable toxicity. The clinical efficacy and adverse events were observed, while serum samples were collected for proteomic analysis. RESULTS: Twenty Three patients were enrolled from January 2022 to March 2023 (median age, 65 years; male, n = 18 [78.3%]; squamous NSCLC, n = 9 [39.1%]; mutant type, n = 13 [56.5%]). The overall response rate (ORR) was 21.7% and disease control rate (DCR) was 73.9%. Median progression-free survival (mPFS) and median overall survival (mOS) was 4.3 months [95% CI: 2.0-6.6] and 9.8 months [95% CI: 7.2-12.4], respectively. The mPFS between PD-L1 positive and negative subgroup has significant difference (6.3 months vs. 2.3 months, p = 0.002). Treatment-related adverse events (TRAEs) occurred in 52.2% of patients. The most common TRAEs were hypothyroidism (26.1%) and fatigue (26.1%). 2 (8.7%) grade 3 adverse events were reported. No adverse reaction related deaths have been observed. Proteomic analysis revealed that the levels of CASP-8, ARG1, MMP12, CD28 and CXCL5 correlated with resistance to the treatment while the levels of CD40-L and EGF related to the favorable response. CONCLUSION: ß-glucan combined with Envafolimab and Endostar has considerable efficacy and safety for immune rechallenge in metastatic NSCLC patients who failed of anti-PD-1 treatment previously, especially for PD-L1 positive patients.

Structural Analysis and Antioxidant Activity of Alkaline-Extracted Glucans from Hericium erinaceus.

An alkali-soluble ß-glucan (AHEP-A-b, 20 kDa) purified from Hericium erinaceus fruiting bodies, was structurally characterized and examined for antioxidant activity. Methylation analysis and NMR spectroscopy show that the backbone of AHEP-A-b is composed of (1→6)-linked-D-ß-glucopyran residues, branched at O-3 of glucopyranose (Glcp) residues with [→3)-ß-D-Glcp-(1→] oligosaccharides or single unit of ß-Glcp. Periodate oxidation analysis and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) indicate that the degree of polymerization (DP) of [→3)-ß-D-Glcp-(1→] side chains is 2 to 8. Functionally, AHEP-A-b is a relatively strong antioxidant as demonstrated by using 2, 2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) free radical (ABTS·+), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, and hydroxyl radicals scavenging assays. The present study lays the foundation for further studies into structure-activity relationships of polysaccharides from H. erinaceus.

Effect of Mono- and Polysaccharide on the Structure and Property of Soy Protein Isolate during Maillard Reaction.

As a protein extracted from soybeans, soy protein isolate (SPI) may undergo the Maillard reaction (MR) with co-existing saccharides during the processing of soy-containing foods, potentially altering its structural and functional properties. This work aimed to investigate the effect of mono- and polysaccharides on the structure and functional properties of SPI during MR. The study found that compared to oat ß-glucan, the reaction rate between SPI and D-galactose was faster, leading to a higher degree of glycosylation in the SPI-galactose conjugate. D-galactose and oat ß-glucan showed different influences on the secondary structure of SPI and the microenvironment of its hydrophobic amino acids. These structural variations subsequently impact a variety of the properties of the SPI conjugates. The SPI-galactose conjugate exhibited superior solubility, surface hydrophobicity, and viscosity. Meanwhile, the SPI-galactose conjugate possessed better emulsifying stability, capability to produce foam, and stability of foam than the SPI-ß-glucan conjugate. Interestingly, the SPI-ß-glucan conjugate, despite its lower viscosity, showed stronger hypoglycemic activity, potentially due to the inherent activity of oat ß-glucan. The SPI-galactose conjugate exhibited superior antioxidant properties due to its higher content of hydroxyl groups on its molecules. These results showed that the type of saccharides had significant influences on the SPI during MR.

An exploratory clinical study of ß-glucan combined with camrelizumab and SOX chemotherapy as first-line treatment for advanced gastric adenocarcinoma.

Background: ß-glucan has been reported to be a potential natural immune modulator for tumor growth inhibition. We aimed to evaluate the efficacy and safety of ß-glucan plus immunotherapy and chemotherapy in the first-line treatment of advanced gastric adenocarcinoma. Methods: This is a phase IB, prospective, single-arm, investigator-initiated trail. Advanced gastric adenocarcinoma patients received ß-glucan, camrelizumab, oxaliplatin, oral S-1 every 3 weeks. The curative effect was evaluated every 2 cycles. The primary endpoints were objective response rate (ORR) and safety, with secondary endpoints were median progression-free survival (mPFS) and median overall survival (mOS). The exploratory endpoint explored biomarkers of response to treatment efficacy. Results: A total of 30 patients had been enrolled, including 20 (66.7%) males and all patients with an ECOG PS score of ≥1. The ORR was 60%, the mPFS was 10.4 months (95% confidence interval [CI], 9.52-11.27), the mOS was 14.0 months (95% CI, 11.09-16.91). A total of 19 patients (63.3%) had TRAEs, with 9 patients (30%) with grade ≥ 3. The most common TRAEs were nausea (53.3%). After 2 cycles of treatment, the levels of IL-2, IFN-γ and CD4+ T cells significantly increased (P < 0.05). Furthermore, biomarker analysis indicated that patient with better response and longer OS exhibited lower GZMA expression at baseline serum. Conclusions: This preliminary study demonstrates that ß-glucan plus camrelizumab and SOX chemotherapy offers favorable efficacy and a manageable safety profile in patients with advanced gastric adenocarcinoma, and further studies are needed to verify its efficacy and safety. Clinical Trial Registration: Chinese Clinical Trials Registry, identifier ChiCTR2100044088.

Safety evaluation of curdlan as a food additive.

The EFSA Panel on Food Additives and Flavourings (FAF) provides a scientific opinion on the safety of curdlan as a new food additive used as firming and gelling agent, stabiliser, thickener. Curdlan is a high molecular weight polysaccharide consisting of ß-1,3-linked glucose units, produced by fermentation from Rhizobium radiobacter biovar 1 strain NTK-u. The toxicological dataset consisted of sub-chronic, chronic and carcinogenicity, reproductive and developmental toxicity studies as well as genotoxicity. In vivo data showed that curdlan is not absorbed as such but is extensively metabolised by the gut microbiota into CO2 and other innocuous compounds. Curdlan was not genotoxic and was well-tolerated with no overt organ-specific toxicity. Effects observed at very high doses of curdlan, such as decreased growth and increased cecum weight, are common for indigestible bulking compounds and therefore considered physiological responses. In a combined three-generation reproductive and developmental toxicity study, decreased pup weight was observed during lactation at 7500 mg curdlan/kg body weight (bw) per day, the highest dose tested. The Panel considered the observed effects as treatment-related and adverse, although likely secondary to nutritional imbalance and identified a conservative no observed adverse effect level (NOAEL) of 2500 mg/kg bw per day. Despite the limitations noted in the dataset, the Panel was able to conclude applying the margin of exposure (MOE) approach. Given that curdlan and its break-down products are not absorbed and that the identified adverse effect is neither systemic nor local, no adjustment factor was deemed necessary. Thus, an MOE of at least 1 was considered sufficient. The highest exposure estimate was 1441 mg/kg bw per day in toddlers at the 95th percentile of the proposed maximum use level exposure assessment scenario. The Panel concluded that there is no safety concern for the use of curdlan as a food additive at the proposed uses and use levels.

Both Hemocyanin and ß-1,3-Glucan-Binding Protein from the Shrimp Shell of Litopenaeus vannamei Are Responsible for Its Color Change from Brown to Red during Thermal Processing.

Because of the composition and structural complexity of crustacean shells, their color change mechanism during thermal processing remains unclear. This study identified and characterized two intrinsic protein components, hemocyanin (Lv-Hc) and ß-1,3-glucan-binding protein (Lv-BGBP) from Litopenaeus vannamei shrimp shells by a combination of ion-exchange chromatography, gel filtration, and mass spectrometry. It was found that a mixture of Lv-Hc, a gray protein, and Lv-BGBP (which is a natural astaxanthin-binding protein with a red color) is responsible for the brown color of fresh shrimp shells. Upon heating to 100 °C, the mixture of these proteins turned red, mimicking the color change observed in cooked shrimp shells. This transition is attributed to the extremely high thermal stability of Lv-BGBP, which has the ability to protect astaxanthin from thermal induced degradation. These findings provide significant insights into the molecular mechanism governing shrimp shell coloration, advancing our understanding of crustacean biochemistry.

Streptomyces castrisilvae sp. nov. and Streptomyces glycanivorans sp. nov., novel soil streptomycetes metabolizing mutan and alternan.

Six bacterial strains, Mut1T, Mut2, Alt1, Alt2, Alt3T, and Alt4, were isolated from soil samples collected in parks in Gothenburg, Sweden, based on their ability to utilize the insoluble polysaccharides α-1,3-glucan (mutan; Mut strains) or the mixed-linkage α-1,3/α-1,6-glucan (alternan; Alt strains). Analysis of 16S rRNA gene sequences identified all strains as members of the genus Streptomyces. The genomes of the strains were sequenced and subsequent phylogenetic analyses identified Mut2 as a strain of Streptomyces laculatispora and Alt1, Alt2 and Alt4 as strains of Streptomyces poriferorum, while Mut1T and Alt3T were most closely related to the type strains Streptomyces drozdowiczii NBRC 101007T and Streptomyces atroolivaceus NRRL ISP-5137T, respectively. Comprehensive genomic and biochemical characterizations were conducted, highlighting typical features of Streptomyces, such as large genomes (8.0-9.6 Mb) with high G+C content (70.5-72.0%). All six strains also encode a wide repertoire of putative carbohydrate-active enzymes, indicating a capability to utilize various complex polysaccharides as carbon sources such as starch, mutan, and cellulose, which was confirmed experimentally. Based on phylogenetic and phenotypic characterization, our study suggests that strains Mut1T and Alt3T represent novel species in the genus Streptomyces for which the names Streptomyces castrisilvae sp. nov. and Streptomyces glycanivorans sp. nov. are proposed, with strains Mut1T (=DSM 117248T=CCUG 77596T) and Alt3T (=DSM 117252T=CCUG 77600T) representing the respective type strains.

Adaptative responses of Neurospora crassa by histidine kinases upon the attack of the arthropod Sinella curviseta.

Histidine kinases (HKs) are important sensor proteins in fungi and play an essential role in environmental adaptation. However, the mechanisms by which fungi sense and respond to fungivores attack via HKs are not fully understood. In this study, we utilized Neurospora crassa to investigate the involvement of HKs in responding to fungivores attack. We found that the 11 HKs in N. crassa not only affected the growth and development, but also led to fluctuations in antioxidant production. Ten mutants in the genes encoding HKs (except ∆phy1) showed increased production of reactive oxygen species (ROS), especially upon Sinella curviseta attack. The ROS burst triggered changes in conidia and perithecial beaks formation, as well as accumulation of ß-glucan, ergothioneine, ergosterol, and carotenoids. ß-glucan was increased in ∆hk9, ∆os1, ∆hcp1, ∆nik2, ∆sln1, ∆phy1 and ∆phy2 mutants compared to the wild-type strain. In parallel, ergothioneine accumulation was improved in ∆phy1 and ∆hk16 mutants and further increased upon attack, except in ∆os1 and ∆hk16 mutants. Additionally, fungivores attack stimulated ergosterol and dehydroergosterol production in ∆hk9 and ∆os1 mutants. Furthermore, deletion of these genes altered carotenoid accumulation, with wild-type strain, ∆hk9, ∆os1, ∆hcp1, ∆sln1, ∆phy2, and ∆dcc1mutants showing an increase in carotenoids upon attack. Taken together, HKs are involved in regulating the production of conidia and antioxidants. Thus, HKs may act as sensors of fungivores attack and effectively improve the adaptive capacity of fungi to environmental stimuli.