Euglena gracilis cells grown in the dark accumulate a β-1,3-glucan called paramylon, synthesized from organic carbon sources. Paramylon has potential applications as a raw material for bioplastics and nanofibers. Strain...Euglena gracilis cells grown in the dark accumulate a β-1,3-glucan called paramylon, synthesized from organic carbon sources. Paramylon has potential applications as a raw material for bioplastics and nanofibers. Strain SM-ZK, a streptomycin-bleached mutant of E. gracilis, lacks chloroplasts permanently and accumulates more paramylon than the wild-type strain. However, data are limited on the fermentation characteristics of this mutant strain. This study compares the cultivation characteristics of E. gracilis strains Z (wild-type strain) and SM-ZK under fed-batch cultivation conditions. Strain SM-ZK showed significantly higher productivity in terms of both biomass yield and glucose consumption than strain Z. Moreover, strain SM-ZK cells appeared to be gradually enlarged during fed-batch cultivation compared with strain Z that grows in uniform sizes. These novel findings support the potential use of strain SM-ZK for industrial-scale production of paramylon.
Medium-chain aldehydes are important precursors of alkanes, which could be used as a biofuel. In this study, we screened 1300 microorganisms-including bacteria (including actinomycetes), yeasts, molds, and basidiomycetes...Medium-chain aldehydes are important precursors of alkanes, which could be used as a biofuel. In this study, we screened 1300 microorganisms-including bacteria (including actinomycetes), yeasts, molds, and basidiomycetes-for their ability to produce tetradecanal from tetradecanoic acid. Among these microorganisms, Klebsiella pneumoniae subsp. pneumoniae NBRC3321 exhibited the highest 1-tetradecanol-producing activity from tetradecanoic acid. This strain was therefore selected as a suitable candidate for aldehyde-producing enzyme analysis. A novel aldehyde-producing acyl-CoA reductase gene (acrI) was isolated from K. pneumoniae subsp. pneumoniae NBRC3321, which comprises 1404 bp encoding a polypeptide of 49.1 kDa. His6-tagged AcrI requires NADH as a coenzyme to convert tetradecanoyl-CoA into tetradecanal. The enzyme catalyzed both acyl-CoA reduction and aldehyde hydrogenation, producing alcohol with acyl-CoA substrates of C6-C12, whereas it catalyzed acyl-CoA reduction producing only aldehydes with acyl-CoA substrates of C14-C16.
This clinical trial assessed the effect of mayonnaise on postprandial glycemic responses to rice. Fifteen Japanese men consumed 150 g of rice with or without 15 g of mayonnaise (designated RM and R dishes, respectively)....This clinical trial assessed the effect of mayonnaise on postprandial glycemic responses to rice. Fifteen Japanese men consumed 150 g of rice with or without 15 g of mayonnaise (designated RM and R dishes, respectively). Blood samples were collected at 0, 30, 45, 60, 90, and 120 min postconsumption to measure glucose, insulin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and free fatty acid (FFA) levels. Compared to the R dish, the RM dish significantly reduced Δglucose at 30 and 45 min and the incremental area under the curve (iAUC) and ΔCmax of glucose. However, no significant differences were observed in Δinsulin. Meanwhile, ΔGIP and ΔFFA from 30 to 120 min and ΔGLP-1 at 30 and 45 min were significantly higher following RM dish intake. The iAUC of GIP and GLP-1, and ΔCmax of GIP were also elevated. These results indicate that adding mayonnaise suppresses postprandial glucose elevation and enhances incretin secretion.
Cupriavidus necator is capable of producing substantial amounts of polyhydroxyalkanoates (PHAs) from various feedstocks. Nevertheless, no documented accounts exist on the utilization of soy sauce oil. Cupriavidusnecator...Cupriavidus necator is capable of producing substantial amounts of polyhydroxyalkanoates (PHAs) from various feedstocks. Nevertheless, no documented accounts exist on the utilization of soy sauce oil. Cupriavidusnecator cultured in a soy sauce oil-supplemented (1.5 wt%) nitrogen-limited mineral salt medium at 30 °C for 4 days yielded a maximum poly(3-hydroxybutyrate) content and production of 63.7 ± 2.45 wt% and 2.3 ± 0.17 g/L, respectively. Recombinant C. necator PHB¯4 harboring PHA synthase from Aeromonas caviae cultured under identical conditions for 3 days exhibited peak poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] content and production of 46.3 ± 10.9 wt% and 2.0 ± 0.5 g/L, respectively. The P(3HB-co-3HHx) productivity and 3HHx mole fraction are analogous to the outcomes achieved with vegetable oils. The molecular weights and thermal properties of the synthetic PHAs were comparable to those of conventional PHAs. These findings endorse the use of soy sauce oil as a sustainable feedstock for bioplastic production.
This mini-review highlights the emerging agricultural applications of iron oxides, the primary form of iron and one of the most abundant elements on Earth. Rice yield is strongly influenced by soil nitrogen fertility, wh...This mini-review highlights the emerging agricultural applications of iron oxides, the primary form of iron and one of the most abundant elements on Earth. Rice yield is strongly influenced by soil nitrogen fertility, which is supported by biological nitrogen fixation. Using soil metatranscriptomic analysis and isolation-cultivation experiments, we recently discovered iron-reducing Deltaproteobacteria as the predominant but previously overlooked drivers of nitrogen fixation in paddy soil. As these bacteria utilize Fe3+ as an electron acceptor during anaerobic respiration, we hypothesized that amending soils with Fe3+-rich iron oxides would enhance their nitrogen-fixing activity. Laboratory and field experiments confirmed that applying iron oxides with low crystallinity significantly stimulated the diazotrophic activity of iron-reducing bacteria, enabling reduced nitrogen fertilizer input in rice cultivation, with a reduced nitrogen burden to the environment. Recognition of iron-reducing diazotrophs has opened a new research frontier: using metals, particularly crystalline forms of iron oxides, in sustainable agricultural systems.
Seafood processing wastewater, rich in organic carbon and nutrients, represents a potential low-cost medium for algal biomass cultivation. Here, we evaluated the growth performance of a naturally adapted microalgae-bacte...Seafood processing wastewater, rich in organic carbon and nutrients, represents a potential low-cost medium for algal biomass cultivation. Here, we evaluated the growth performance of a naturally adapted microalgae-bacterial consortium isolated from a seafood processing facility primarily handling skipjack tuna. The consortium was cultured directly in raw wastewater without nutrient supplementation. Within 9 days, chlorophyll concentration increased fivefold and total suspended solids nearly doubled, indicating substantial biomass accumulation. Dissolved organic carbon and phosphate declined by 85% and 68%, respectively, indicating nutrient assimilation by the microbial community. The culture also showed a pH increase, consistent with active photosynthetic carbon uptake. Ammonium transiently accumulated before declining during algal growth, while nitrate remained low and nitrite undetectable, indicating a nitrogen cycle dominated by ammonium with minimal oxidation. These results demonstrate the feasibility of valorizing seafood wastewater for microalgal biomass production and provide a basis for sustainable, resource-oriented applications of industrial effluents.
The intramolecular Diels-Alder reaction was employed for the assembly of the trans-decalin structure of cladoic acid, an anti-Trypanosoma cruzi active polyketide isolated from a fungus of the genus Cladosporium. Although...The intramolecular Diels-Alder reaction was employed for the assembly of the trans-decalin structure of cladoic acid, an anti-Trypanosoma cruzi active polyketide isolated from a fungus of the genus Cladosporium. Although the cycloaddition provided the desired trans-octalin as a minor product, the method was effective for simultaneously constructing four stereocenters in the B-ring of cladoic acid.
Diabetic nephropathy is a kidney disease aggravated by the uremic toxin indoxyl sulfate, which is produced from indole by the gut microbiota. Targeting the bacterial enzyme tryptophan indole-lyase (TIL), which produces i...Diabetic nephropathy is a kidney disease aggravated by the uremic toxin indoxyl sulfate, which is produced from indole by the gut microbiota. Targeting the bacterial enzyme tryptophan indole-lyase (TIL), which produces indole from l-tryptophan, could be a promising therapeutic strategy. This study investigates diketopiperazines (DKPs), particularly cyclo-glycylproline [cyclo(Gly-Pro)], as potential TIL inhibitors. Cyclo(Gly-Pro) and other DKPs moderately inhibited indole production from l-tryptophan in crude bacterial extracts. Cyclo(Gly-Pro) was not metabolized by the bacteria and did not affect their viability. Cyclo(Gly-Pro) inhibited the Escherichia coli TIL with a Ki value of 17 μM through a mixed-type mechanism. Computational docking studies supported this finding, showing that cyclo(Gly-Pro) binds near the active site of TIL. Additionally, cyclo(Gly-Pro) significantly reduced indole production in bacterial cultures and human fecal samples. These findings suggest that cyclo(Gly-Pro) could be a promising dietary supplement or a lead compound for developing new therapeutics to prevent or treat diabetic nephropathy.
Chemotactic responses of Aurantiochytrium limacinum SR21 to 90 distinct compounds including sugars, organic acids, alcohols, amino acids, amines, aromatic compounds, sulfoxides, vitamins, nucleosides, and inorganic compo...Chemotactic responses of Aurantiochytrium limacinum SR21 to 90 distinct compounds including sugars, organic acids, alcohols, amino acids, amines, aromatic compounds, sulfoxides, vitamins, nucleosides, and inorganic compounds were analyzed. While the zoospores were significantly attracted to several amino acids, they did not respond to their typical nutrients such as sugars or organic acids, suggesting that the chemotaxis may not be directly involved in the search for their nutrition. Zoospores were also attracted to vanillin, which is a component of lignin and a major component of land plant cell walls. This suggests that Aurantiochytrium sp. may be involved in the cycling of carbons in terrestrial plant biomass between land and sea via lignin. Structural comparisons of responding and nonresponding vanilloids indicated that the hydrocarbon chain at position 1, the alkoxyl group at position 3, and the hydroxyl group at position 4 may be particularly important in vanilloid recognition.
Senescent cells contribute to tissue dysfunction and the progression of age-related diseases. Senolytic therapies, which selectively eliminate these cells, have demonstrated beneficial effects in preclinical models by re...Senescent cells contribute to tissue dysfunction and the progression of age-related diseases. Senolytic therapies, which selectively eliminate these cells, have demonstrated beneficial effects in preclinical models by restoring tissue function and delaying age-related decline. Naturally occurring compounds are gaining attention due to their structural diversity and low toxicity. Among these, triterpenes, plant-derived molecules with anti-inflammatory and protective properties, are emerging as therapeutic candidates for targeting cellular senescence. Here, we aimed to evaluate the senolytic activity of β-amyrin, a plant-derived triterpene, in established fibroblast models. Using senescent cells of murine and human origin, we found that β-amyrin selectively induced cell death in senescent cells. Mechanistic analyses suggest that this effect involves cannabinoid receptor 2 signaling and proceeds independently of caspase activation. These findings highlight β-amyrin as a promising senolytic compound with a potentially unique mechanism of action.
Biomineral proteins play critical roles in controlling the polymorph, orientation, and morphology of calcium carbonate (CaCO3) in mollusk shells. Many of these proteins are intrinsically disordered and contain low-comple...Biomineral proteins play critical roles in controlling the polymorph, orientation, and morphology of calcium carbonate (CaCO3) in mollusk shells. Many of these proteins are intrinsically disordered and contain low-complexity regions (IDPs). Structural and functional analyses of IDPs are highly challenging because of their structural flexibility. This mini review highlights recent research elucidating the conformational changes and mineral-binding mechanisms of two representative biomineral proteins from Pinctada fucata: Pif 80, which promotes tablet-shaped aragonite formation in the nacreous layer, and ligament methionine-rich protein, which facilitates the organization of aragonite nanofibers in the hinge ligament. Using solution nuclear magnetic resonance in combination with CaCO3 dispersive particles, we characterized structural transitions in short repeat peptides derived from these proteins. These findings provide insight into the molecular mechanisms underlying organic-inorganic interactions during biomineralization and offer principles for designing bioinspired materials with controllable mineralization properties.
Capsaicin and menthol, agonists of transient receptor potential channels, are known to influence energy metabolism. However, their roles in skeletal muscle function are unclear. Therefore, this study aimed to investigate...Capsaicin and menthol, agonists of transient receptor potential channels, are known to influence energy metabolism. However, their roles in skeletal muscle function are unclear. Therefore, this study aimed to investigate the effects of capsaicin and menthol on skeletal muscle differentiation and muscle quality. In vitro, capsaicin and menthol increased myosin heavy chain (MYH)4 expression, while menthol upregulated MYH1. Both compounds reduced MYH2 and MYH7 levels. Additionally, capsaicin enhanced uncoupling protein (UCP)3 expression, and menthol increased UCP2, UCP3, and M-type creatine kinase. In vivo, topical application during voluntary running did not affect body or muscle mass, but capsaicin reduced fat mass and increased locomotor activity. Menthol enhanced light-phase activity. Both treatments elevated MYH4, UCP2, and UCP3 in muscle, and suppressed myostatin expression. These findings suggest capsaicin and menthol modulate skeletal muscle phenotype and metabolism through both direct cellular effects and increased physical activity.
Carbon catabolite repression (CCR) enables microorganisms to preferentially utilize energetically favorable carbon sources. In Aspergillus oryzae, the transcription factor CreA plays a central role in carbon source metab...Carbon catabolite repression (CCR) enables microorganisms to preferentially utilize energetically favorable carbon sources. In Aspergillus oryzae, the transcription factor CreA plays a central role in carbon source metabolism via CCR, although its function under various culture conditions remains insufficiently determined. In this study, we performed genomic systematic evolution of ligands via exponential enrichment-sequencing (gSELEX-Seq) using the DNA-binding domain of CreA to identify candidate CreA-binding regions within the genome. Motif analysis revealed a consensus binding site overlapping the previously reported 5'-SYGGRG-3' core. RNA-Seq analysis using the A. oryzae ΔcreA strain cultured under CCR release conditions revealed significant differences in the expression of 486 genes, including transporters, transcription factors, and sugar metabolism enzymes. Integration of gSELEX-Seq data and transcriptome profiles revealed nine candidate genes directly regulated by CreA. These findings enhance our understanding of the multifaceted regulatory network of CreA in A. oryzae, providing a framework for further functional studies.
Sugar intake induces the secretion of fibroblast growth factor 21 (FGF21) from the liver. Subsequently, FGF21 acts on the hypothalamus to reduce sugar intake. As simple sugars are obesogenic, low-calorie rare sugars can...Sugar intake induces the secretion of fibroblast growth factor 21 (FGF21) from the liver. Subsequently, FGF21 acts on the hypothalamus to reduce sugar intake. As simple sugars are obesogenic, low-calorie rare sugars can be used as alternatives. Accordingly, d-allulose, d-tagatose, and d-sorbitol induce Fgf21 expression in primary mouse hepatocytes. Carbohydrate-responsive element-binding protein regulates simple sugar-induced FGF21 expression. Therefore, this study aimed to determine whether the same mechanism was responsible for rare sugar-induced FGF21 expression. Promoter analysis, knockdown assays, and chromatin immunoprecipitation were performed using primary mouse hepatocytes. Our findings demonstrate that these three rare sugars transactivate the mouse Fgf21 promoter by inducing activating transcription factor 4 (ATF4), which binds to an amino acid response element located 1027 base pairs upstream of the transcription start site. These results suggested a novel mechanism for sugar-induced FGF21 expression.
Methylotrophs live symbiotically with plants in the phyllosphere. Because the leaf surface is a harsh environment with light, temperature, and low trophic levels, microorganisms on the leaves may have oligotrophic metabo...Methylotrophs live symbiotically with plants in the phyllosphere. Because the leaf surface is a harsh environment with light, temperature, and low trophic levels, microorganisms on the leaves may have oligotrophic metabolism or use light energy to compensate for the low-carbon conditions for their growth. Various natural samples, including plants, have been screened for oligotrophic and/or light-driven methylotrophs.
Bifidobacteria are Gram-positive, anaerobic bacteria known for their health-promoting effects. However, a comprehensive analysis of middle- and long-chain fatty acids in bifidobacteria remains elusive. This study aimed t...Bifidobacteria are Gram-positive, anaerobic bacteria known for their health-promoting effects. However, a comprehensive analysis of middle- and long-chain fatty acids in bifidobacteria remains elusive. This study aimed to evaluate fatty acid accumulation among 43 strains covering 40 species/subspecies, and to elucidate interspecies and interstrain variations. Analysis of their cell-associated fatty acids revealed significant differences in total fatty acid levels. Bifidobacterium thermacidophilum and related species exhibited notably high accumulation of multiple fatty acids (eg decanoic acid, cis-7-C16:1). Among Bifidobacterium breve strains, M-16V produced significantly more cis-7-C16:1 than the others. Additionally, a homology analysis targeting cyclopropane fatty acid synthase was performed to determine the genetic basis of cis-9,10-methyleneoctadecanoic acid (cyclo-C19:0) production. Only strains possessing the homolog produced cyclo-C19:0. These results highlight substantial variation in fatty acid accumulation among bifidobacteria, which could influence their probiotic functionalities. This study provides a foundation for future research on the health benefits of bifidobacterial fatty acid profiles.
Matcha, a Japanese powdered green tea, enhances Drosophila resistance to oxidative stress. Transcriptome analysis shows activation of detoxification and antioxidant pathways, likely driven by caffeine-catechin synergy. U...Matcha, a Japanese powdered green tea, enhances Drosophila resistance to oxidative stress. Transcriptome analysis shows activation of detoxification and antioxidant pathways, likely driven by caffeine-catechin synergy. Unlike green tea catechins, matcha did not extend lifespan under high-protein diets, underscoring complex physiological effects and validating Drosophila as a nutrigenomic model.
This study aimed to elucidate the functions of saline-alkaline inducible genes encoding OsCHX11 and OsCHX16, members of the cation/H+ exchanger (CHX) family, under different component of saline-alkaline conditions. Rice...This study aimed to elucidate the functions of saline-alkaline inducible genes encoding OsCHX11 and OsCHX16, members of the cation/H+ exchanger (CHX) family, under different component of saline-alkaline conditions. Rice biomass under carbonate-based (50 mm Na+ with carbonates) and high-pH (50 mm Na+ without carbonates) conditions was similar, whereas higher Na+/K+ ratio was observed under carbonate-based conditions. Under carbonate-based conditions, only OsCHX16 was significantly expressed, whereas both OsCHX11 and OsCHX16 were highly expressed under high pH conditions. The yeast complementation assay showed that OsCHX11 and OsCHX16 improved the yeast growth under saline, carbonate-based, and high-pH conditions by increasing K+ concentration. Taken together, these results suggest that OsCHX11 and OsCHX16 may contribute to the K+ uptake system under saline-alkaline conditions with or without carbonates at cell level.
Antimycin A (AA) is a widely used inhibitor to study photosynthesis and respiration. In photosynthesis, it is commonly used to inhibit a pathway of cyclic electron flow around photosystem I (CEF-PSI), but has also been r...Antimycin A (AA) is a widely used inhibitor to study photosynthesis and respiration. In photosynthesis, it is commonly used to inhibit a pathway of cyclic electron flow around photosystem I (CEF-PSI), but has also been reported to affect photosystem II (PSII), not involved in CEF-PSI. Although concerns have been raised about AA's specificity, its impact on PSII activity remains unclear. AA3 was recently proposed as a more specific inhibitor of the same CEF-PSI pathway. In the mitochondrial respiratory chain, AA inhibits complex III, like myxothiazol. Here, we investigated the direct effects of AA, AA3, and myxothiazol on PSII activity and linear photosynthetic electron transport using isolated plant PSII and thylakoid membranes. AA, but neither AA3 nor myxothiazol, directly suppressed PSII activity and linear electron transport. Furthermore, the extent of AA's effects was batch-dependent. Thus, we propose using AA3 to inhibit CEF-PSI, and myxothiazol to inhibit complex III, instead of AA.
Zinc (Zn), Copper (Cu), and Manganese (Mn) are micronutrients that are essential for biological functions. They act as cofactors for numerous proteins and serve as signaling molecules. Although recent studies have signif...Zinc (Zn), Copper (Cu), and Manganese (Mn) are micronutrients that are essential for biological functions. They act as cofactors for numerous proteins and serve as signaling molecules. Although recent studies have significantly advanced our understanding of the individual roles of these metals, their homeostatic interactions remain largely unclear, except for a few well-documented cases, most notably the well-known competition between Zn and Cu for intestinal absorption. Moreover, recent research in vertebrates has suggested that Mn metabolism is closely linked to Zn metabolism in various cellular processes. Investigating the regulatory mechanisms governing homeostasis of essential trace metals is crucial for elucidating their functions in cellular systems. In this review, we provide a brief overview of the recent advances in understanding the competition between Cu, Mn, and Zn, with a particular focus on the interaction of Zn with the other two metals.