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2-Keto-3-deoxy-galactonate (KDGal) serves as a pivotal metabolic intermediate within both the fungal d-galacturonate pathway, which is integral to pectin catabolism, and the bacterial DeLey-Doudoroff pathway for d-galactose catabolism. The presence of KDGal enantiomers, l-KDGal and d-KDGal, varies across these pathways. Fungal pathways generate l-KDGal through the reduction and dehydration of d-galacturonate, whereas bacterial pathways produce d-KDGal through the oxidation and dehydration of d-galactose. Two distinct catabolic routes further metabolize KDGal: a nonphosphorolytic pathway that employs aldolase and a phosphorolytic pathway involving kinase and aldolase. Recent findings have revealed that l-KDGal, identified in the bacterial catabolism of 3,6-anhydro-l-galactose, a major component of red seaweeds, is also catabolized by Escherichia coli, which is traditionally known to be catabolized by specific fungal species, such as Trichoderma reesei. Furthermore, the potential industrial applications of KDGal and its derivatives, such as pyruvate and d- and l-glyceraldehyde, are underscored by their significant biological functions. This review comprehensively outlines the catabolism of l-KDGal and d-KDGal across different biological systems, highlights stereospecific methods for discriminating between enantiomers, and explores industrial application prospects for producing KDGal enantiomers. Key points: • KDGal is a metabolic intermediate in fungal and bacterial pathways • Stereospecific enzymes can be used to identify the enantiomeric nature of KDGal • KDGal can be used to induce pectin catabolism or produce functional materials [ABSTRACT FROM AUTHOR]

Menopause is a significant phase in a woman's life. Menopausal symptoms can affect overall well-being and quality of life. Conventionally, hormone replacement therapy (HRT) is used to alleviate menopausal symptoms; however, depending on the conditions, HRT may lead to side effects, necessitating the exploration of alternative therapies with fewer side effects. In this study, we investigated the effects of a combination of soybean germ extract (S30) containing 30% (w/w) isoflavone and a probiotic, Lactobacillus gasseri (LGA1), on menopausal conditions in an ovariectomized (OVX) rat model. We evaluated the impact of S30+LGA on body weight, estrogen markers, uterine and bone health, vascular markers, and neurotransmitter levels. The results revealed that treatment with S30+LGA1 significantly improved body weight and uterine and bone health. Moreover, S30+LGA1 demonstrated promising effects on lipid profile, liver function, and vascular markers and positively impacted serotonin and norepinephrine levels, indicating potential mood-enhancing effects. In conclusion, S30+LGA1, possessing anti-menopausal effects in vitro and in vivo, can be recommended as a soy-based diet, which offers various health benefits, especially for menopausal women. [ABSTRACT FROM AUTHOR]

Agarobiose (AB; d-galactose-β-1,4-AHG), produced by one-step acid hydrolysis of agarose of red seaweed, is considered a promising cosmetic ingredient due to its skin-moisturizing activity. In this study, the use of AB as a cosmetic ingredient was found to be hampered due to its instability at high temperature and alkaline pH. Therefore, to increase the chemical stability of AB, we devised a novel process to synthesize ethyl-agarobioside (ethyl-AB) from the acid-catalyzed alcoholysis of agarose. This process mimics the generation of ethyl α-glucoside and glyceryl α-glucoside by alcoholysis in the presence of ethanol and glycerol during the traditional Japanese sake-brewing process. Ethyl-AB also showed in vitro skin-moisturizing activity similar to that of AB, but showed higher thermal and pH stability than AB. This is the first report of ethyl-AB, a novel compound produced from red seaweed, as a functional cosmetic ingredient with high chemical stability. [ABSTRACT FROM AUTHOR]

2-keto-3-deoxy sugar acids, which have potential as precursors in medicinal compound production, have gained attention in various fields. Among these acids, 2-keto-3-deoxy-l-galactonate (KDGal) has been biologically produced from D-galacturonate originating from plant-derived pectin. KDGal is also found in the catabolic pathway of 3,6-anhydro-l-galactose (AHG), the main component of red-algae-derived agarose. AHG is converted to 3,6-anhydrogalactonate by AHG dehydrogenase and subsequently isomerized to KDGal by 3,6-anhydrogalactonate cycloisomerase. Therefore, we used the above-described pathway to produce KDGal from agarose. Agarose was depolymerized to AHG and to agarotriose (AgaDP3) and agaropentaose (AgaDP5), both of which have significantly higher molecular weights than AHG. When only AHG was converted to KDGal, AgaDP3 and AgaDP5 remained unreacted. Finally, KDGal was effectively purified from the enzymatic products by size-exclusion chromatography based on the differences in molecular weights. These results show that KDGal can be enzymatically produced and purified from agarose for use as a precursor to high-value products. [ABSTRACT FROM AUTHOR]

[Display omitted] • For metabolome sample preparation, rapid quenching of cell metabolism is essential. • Cold methanol quenching resulted in severe losses of intracellular metabolites. • We developed a new fast filtration method using a vacuum manifold system. • When using the fast filtration, most metabolites were highly preserved. • This new fast filtration method can be applied to yeast metabolome analysis. For metabolome sample preparation, rapid quenching of cellular metabolism without severe loss of intracellular metabolites is important. Here, we comparatively evaluated the two sampling methods, cold methanol quenching and fast filtration, for one of the most important industrial microorganisms, yeast Saccharomyces cerevisiae. The latter, using a vacuum manifold system capable of processing up to twenty samples simultaneously, was developed here. The results showed that the cold methanol quenching method resulted in severe losses of intracellular metabolites but that sugars and sugar phosphates were highly preserved. In comparison, the fast filtration method better preserved most metabolites with less extracellular contamination. Our results suggested that the fast filtration method with a vacuum manifold system can be widely applied to yeast metabolome analysis due to its simplicity, robustness, and lack of significant intracellular metabolite loss. [ABSTRACT FROM AUTHOR]

Recently, the utilization of renewable biomass instead of fossil fuels for producing fuels and chemicals has received much attention due to the global climate change. Among renewable biomass, marine algae are gaining importance as third generation biomass feedstocks owing to their advantages over lignocellulose. Particularly, red macroalgae have higher carbohydrate contents and simpler carbohydrate compositions than other marine algae. In red macroalgal carbohydrates, 3,6-anhydro- L -galactose (AHG) is the main sugar composing agarose along with D -galactose. However, AHG is not a common sugar and is chemically unstable. Thus, not only AHG but also red macroalgal biomass itself cannot be efficiently converted or utilized. Here, we biologically upgraded AHG to a new platform chemical, its sugar alcohol form, 3,6-anhydro- L -galactitol (AHGol), an anhydrohexitol. To accomplish this, we devised an integrated process encompassing a chemical hydrolysis process for producing agarobiose (AB) from agarose and a biological process for converting AB to AHGol using metabolically engineered Saccharomyces cerevisiae to efficiently produce AHGol from agarose with high titers and yields. AHGol was also converted to an intermediate chemical for plastics, isosorbide. To our knowledge, this is the first demonstration of upgrading a red macroalgal biomass component to a platform chemical via a new biological route, by using an engineered microorganism. [ABSTRACT FROM AUTHOR]

Bioconversion of xylose—the second most abundant sugar in nature—into high‐value fuels and chemicals by engineered Saccharomyces cerevisiae has been a long‐term goal of the metabolic engineering community. Although most efforts have heavily focused on the production of ethanol by engineered S. cerevisiae, yields and productivities of ethanol produced from xylose have remained inferior as compared with ethanol produced from glucose. However, this entrenched focus on ethanol has concealed the fact that many aspects of xylose metabolism favor the production of nonethanol products. Through reduced overall metabolic flux, a more respiratory nature of consumption, and evading glucose signaling pathways, the bioconversion of xylose can be more amenable to redirecting flux away from ethanol towards the desired target product. In this report, we show that coupling xylose consumption via the oxidoreductive pathway with a mitochondrially‐targeted isobutanol biosynthesis pathway leads to enhanced product yields and titers as compared to cultures utilizing glucose or galactose as a carbon source. Through the optimization of culture conditions, we achieve 2.6 g/L of isobutanol in the fed‐batch flask and bioreactor fermentations. These results suggest that there may be synergistic benefits of coupling xylose assimilation with the production of nonethanol value‐added products. [ABSTRACT FROM AUTHOR]

L‐Fucose (6‐deoxy‐L‐galactose) is a major constituent of glycans and glycolipids in mammals. Fucosylation of glycans can confer unique functional properties and may be an economical way to manufacture L‐fucose. Research can extract L‐fucose directly from brown algae, or by enzymatic hydrolysis of L‐fucose‐rich microbial exopolysaccharides. However, these L‐fucose production methods are not economical or scalable for various applications. We engineered an Escherichia coli strain to produce L‐fucose. Specifically, we modified the strain genome to eliminate endogenous L‐fucose and lactose metabolism, produce 2′‐fucosyllactose (2′‐FL), and to liberate L‐fucose from 2′‐FL. This E. coli strain produced 16.7 g/L of L‐fucose with productivity of 0.1 g·L−1·h−1 in a fed‐batch fermentation. This study presents an efficient one‐pot biosynthesis strategy to produce a monomeric form of L‐fucose by microbial fermentation, making large‐scale industrial production of L‐fucose feasible. This study presents an efficient one‐pot biosynthesis strategy to produce L‐fucose by microbial fermentation using engineered Escherichia coli. Specifically, the authors modified the strain genome to eliminate endogenous L‐fucose and lactose metabolism, produce 2‐fucosyllactose (2‐FL), and to liberate L‐fucose from 2‐FL. Finally, this engineered E. coli strain produced 16.7 g/L of L‐fucose with a productivity of 0.1 g·L-1·h-1 in a fed‐batch fermentation. [ABSTRACT FROM AUTHOR]

Simultaneous saccharification and fermentation (SSF) of cellulose via engineered Saccharomyces cerevisiae is a sustainable solution to valorize cellulose into fuels and chemicals. In this study, we demonstrate the feasibility of direct conversion of cellulose into ethanol and a biodegradable surfactant, ethyl‐β‐d‐glucoside, via an engineered yeast strain (i.e., strain EJ2) expressing heterologous cellodextrin transporter (CDT‐1) and intracellular β‐glucosidase (GH1‐1) originating from Neurospora crassa. We identified the formation of ethyl‐β‐d‐glucoside in SSF of cellulose by the EJ2 strain owing to transglycosylation activity of GH1‐1. The EJ2 strain coproduced 0.34 ± 0.03 g ethanol/g cellulose and 0.06 ± 0.00 g ethyl‐β‐d‐glucoside/g cellulose at a rate of 0.30 ± 0.02 g·L−1·h−1 and 0.09 ± 01 g·L−1·h−1, respectively, during the SSF of Avicel PH‐101 cellulose, supplemented only with Celluclast 1.5 L. Herein, we report a possible coproduction of a value‐added chemical (alkyl‐glucosides) during SSF of cellulose exploiting the transglycosylation activity of GH1‐1 in engineered S. cerevisiae. This coproduction could have a substantial effect on the overall technoeconomic feasibility of theSSF of cellulose. Simultaneous saccharification and fermentation (SSF) of cellulose via engineered Saccharomyces cerevisiae s a sustainable solution to valorize cellulose into fuels and chemicals. In this study, we demonstrate the feasibility of direct conversion of cellulose into ethanol and a biodegradable surfactant, ethyl‐β‐d‐glucoside, via an engineered yeast strain (i.e., strain EJ2) expressing heterologous cellodextrin transporter (CDT‐1) and intracellular β‐glucosidase (GH1‐1) originating from Neurospora crassa. We identified the formation of ethyl‐β‐d‐glucoside in SSF of cellulose by the EJ2 strain owing to transglycosylation activity of GH1‐1. [ABSTRACT FROM AUTHOR]