Creating a New Pathway in Corynebacterium glutamicum for the Production of Taurine as a Food Additive.

Taurine is a biologically and physiologically valuable food additive. However, commercial taurine production mainly relies on environmentally harmful chemical synthesis. Herein, for the first time in bacteria, we attempted to produce taurine in metabolically engineered Corynebacterium glutamicum. The taurine-producing strain was developed by introducing cs, cdo1, and csad genes. Interestingly, while the control strain could not produce taurine, the engineered strains successfully produced taurine via the newly introduced metabolic pathway. Furthermore, we investigated the effect of a deletion strain of the transcriptional repressor McbR gene on taurine production. As a result, sulfur accumulation and l-cysteine biosynthesis were reinforced by the McbR deletion strain, which further increased the taurine production by 2.3-fold. Taurine production of the final engineered strain Tau11 was higher than in other previously reported strains. This study demonstrated a potential approach for eco-friendly biosynthesis as an alternative to the chemical synthesis of a food additive.

Metabolic Design of Corynebacterium glutamicum for Production of l-Cysteine with Consideration of Sulfur-Supplemented Animal Feed.

l-Cysteine is a valuable sulfur-containing amino acid widely used as a nutrition supplement in industrial food production, agriculture, and animal feed. However, this amino acid is mostly produced by acid hydrolysis and extraction from human or animal hairs. In this study, we constructed recombinant Corynebacterium glutamicum strains that overexpress combinatorial genes for l-cysteine production. The aims of this work were to investigate the effect of the combined overexpression of serine acetyltransferase (CysE), O-acetylserine sulfhydrylase (CysK), and the transcriptional regulator CysR on l-cysteine production. The CysR-overexpressing strain accumulated approximately 2.7-fold more intracellular sulfide than the control strain (empty pMT-tac vector). Moreover, in the resulting CysEKR recombinant strain, combinatorial overexpression of genes involved in l-cysteine production successfully enhanced its production by approximately 3.0-fold relative to that in the control strain. This study demonstrates a biotechnological model for the production of animal feed supplements such as l-cysteine using metabolically engineered C. glutamicum.

BLT2 is a pro-tumorigenic mediator during cancer progression and a therapeutic target for anti-cancer drug development.

Cancer is a leading cause of death worldwide and has been linked to inflammation. Leukotriene B4 (LTB4) is synthesized from arachidonic acid via the 5-lipoxygenase pathway and is a potent chemoattractant for inflammatory cells. LTB4 was recently shown to be associated with the pathogenesis of inflammatory diseases, including cancer. Of the two known LTB4 receptors, BLT1 and BLT2, the biological roles of the low-affinity LTB4 receptor 2, BLT2, have only recently been elucidated. This review focuses on recent discoveries regarding BLT2 and its roles in cancer progression and the downstream signaling mechanisms of the BLT2-linked signaling cascade in cancer cells. We believe that these findings will facilitate the development of new cancer treatments.

Production of 10-hydroxystearic acid from oleic acid and olive oil hydrolyzate by an oleate hydratase from Lysinibacillus fusiformis.

A recombinant enzyme from Lysinibacillus fusiformis was expressed, purified, and identified as an oleate hydratase because the hydration activity of the enzyme was the highest for oleic acid (with a k (cat) of 850 min(-1) and a K (m) of 540 µM), followed by palmitoleic acid, γ-linolenic acid, linoleic acid, myristoleic acid, and α-linolenic acid. The optimal reaction conditions for the enzymatic production of 10-hydroxystearic acid were pH 6.5, 35 °C, 4% (v/v) ethanol, 2,500 U ml(-1) (8.3 mg ml(-1)) of enzyme, and 40 g l(-1) oleic acid. Under these conditions, 40 g l(-1) (142 mM) oleic acid was converted into 40 g l(-1) (133 mM) 10-hydroxystearic acid for 150 min, with a molar yield of 94% and a productivity of 16 g l(-1) h(-1), and olive oil hydrolyzate containing 40 g l(-1) oleic acid was converted into 40 g l(-1) 10-hydroxystearic acid for 300 min, with a productivity of 8 g l(-1) h(-1).

Antioxidant activity of glyceollins derived from soybean elicited with Aspergillus sojae.

The extract of soybean exposed to biotic elicitors such as food-grade fungus is known to have antioxidant activity. Glyceollins were major bioactive compounds present in soybean elicited by fungi and shown to have antifungal and anticancer activities. The purpose of present study was to evaluate the antioxidant activities of glyceollins by measuring ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, singlet oxygen quenching, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, hydroxyl radical scavenging activity, and lipid peroxidation inhibition. In addition, the antioxidant potential of glyceollins were measured by a fluorescent probe, 2',7'-dichlorofluorescin diacetate (DCFDA), and dihydroethidium (DHE) in mouse hepatoma hepa1c1c7 cells in which they were insulted with H2O2 to generate reactive oxygen species (ROS). Glyceollins showed a strong reducing power and inhibited lipid peroxidation, with significant scavenging activities of radicals including singlet oxygen, superoxide anion, ABTS, and DPPH. We also found that glyceollins significantly suppressed H2O2-induced ROS production in hepa1c1c7 cells. Therefore, glyceollins deserve further study as natural antioxidants and nutraceuticals.