Research Progress on Biosynthesis and Regulation of Conjugated Linoleic Acid in Lactic Acid Bacteria.

Conjugated linoleic acid (CLA) has gained considerable attention and has been extensively studied owing to its physiological functions, including weight loss, immune regulation, and anti-carcinogenesis. However, the CLA content is very low in natural sources and insufficient to exert a probiotic effect. Additionally, its chemical synthesis is limited by the lack of isomer selectivity, harsh reaction conditions, and the introduction of organic solvents.

Regulatory Effect of Transcriptional Regulator TetR on the Synthesis of Conjugated Linoleic Acid in AR195.

Conjugated linoleic acid (CLA) possesses anticancer, anti-inflammatory, and antiobesity properties, making it a significant research focus. In this study, we identified TetR, a TetR/AcrR family transcriptional regulator encoded by , as the transcriptional regulator of CLA synthesis in AR195. TetR binds to the promoter regions of the CLA synthesis genes, including the operon and , thereby enhancing CLA biosynthesis.

Characterization of a Panel of Constitutive Promoters from for Fine-Tuning Gene Expression.

(homotypic synonym: ) is receiving increasing attention as a prominent vehicle for the delivery of live vaccines. This can hardly be achieved without developing tools for the genetic manipulation of , and the paucity of studies on endogenous promoters has attracted our attention. Here, we report the discovery and characterization of 29 candidate promoters identified from subsp.

Cobalt-Promoted Photoredox 1,2-Amidoamination of Alkenes with -Sulfonamidopyridin-1-ium Salts and Free Amines.

A cobalt-promoted photoredox 1,2-amidoamination of alkenes with -sulfonamidopyridin-1-ium salts and free amines for the synthesis of unsymmetrical vicinal diamines has been developed. The reaction handles -(sulfonamido)pyridin-1-ium salts as the sulfonamidyl radical precursors and free amines as the nucleophilic terminating reagents to enable the formation of two new C(sp)-N bonds in a single reaction step and offers a route to selectively producing unsymmetrical vicinal diamines with an exquisite selectivity and a good compatibility of functional groups.

Nickel-Catalyzed Reductive Cross-Coupling of Propargylic Acetates with Chloro(vinyl)silanes: Access to Silylallenes.

Because of their various reactivities, propargyl acetates are refined chemical intermediates that are extensively applied in pharmaceutical synthesis. Currently, reactions between propargyl acetates and chlorosilanes may be the most effective method for synthesizing silylallenes. Nevertheless, owing to the adaptability and selectivity of substrates, transition metal catalysis is difficult to achieve.

Divergent [2 + ] Heteroannulation of β-CF-1,3-enynes with Alkyl Azides via Hydrogen Atom Transfer and Radical Substitution.

A copper-promoted divergent intermolecular [2 + ] heteroannulation of β-CF-1,3-enynes with alkyl azides via alkyl radical-driven HAT and radical substitution (C-C bond formation) to form four- to ten-membered saturated -heterocycles is developed. This method enables the aryl-induced or kinetically controlled site selective functionalization of the remote C(sp)-H bonds at positions 2, 3, 4, 5, 6, 7, or 8 toward the nitrogen atom through triplet nitrene formation, radical addition across the C═C bond, HAT and radical substitution cascades, and features a broad substrate scope, excellent site selectivity, and facile late-stage derivatization of bioactive molecules. Initial deuterium-labeling and control experiments shed light on the reaction mechanism via nitrene formation and HAT.

Electroreductive Carboxylation of Propargylic Acetates with CO: Access to Tetrasubstituted 2,3-Allenoates.

An electroreductive carboxylation of propargylic alcohols with CO and then workup with TMSCHN to construct tetrasubstituted 2,3-allenoates is developed. This method allows the incorporation of an external ester group into the resulting allene system through electroreduction, carboxylation, and deacetoxylation cascades. Mechanistically, electricity on/off experiments and cyclic voltammetry analysis support the preferential generation of the CO radical anion or the 3-aryl propargylic acetate radical anion based on the electron nature of the aryl rings.

Cobalt-Promoted Electroreductive Cross-Coupling of Prop-2-yn-1-yl Acetates with Chloro(vinyl)silanes.

An electroreductive cross-coupling of prop-2-yn-1-yl acetates with chloro(vinyl)silanes for producing tetrasubstituted silylallenes is developed. The method enables the formation of a new C─Si bond through the cathodic reduction formation of the silyl radical, radical addition across the C≡C bond, the alkenyl anion intermediate formation, and deacetoxylation and represents a mild, practical route to the synthesis of silylallenes. Mechanistic studies reveal that CoCl acts as the mediator to promote the formation of the alkenyl anion intermediate via electron transfer.

The Arginine Repressor ArgR Controls Conjugated Linoleic Acid Biosynthesis by Activating the Operon in .

CLA (conjugated linoleic acid) has attracted substantial attention due to its physiological functions, including regulating immunity, reducing obesity, and contributing to cancer suppression. In Lactiplantibacillus plantarum, CLA oleate hydratase (CLA-HY), CLA short-chain dehydrogenase (CLA-DH), and CLA acetoacetate decarboxylase (CLA-DC) catalyze the biotransformation of linoleic acid (LA) to CLA. However, the underlying transcriptional regulation mechanism of this pathway remains largely unknown.

Determination of the regulatory network and function of the lysR-type transcriptional regulator of Lactiplantibacillus plantarum, LpLttR.

Background: Lactiplantibacillus plantarum has various healthcare functions including the regulation of immunity and inflammation, reduction of serum cholesterol levels, anti-tumor activity, and maintenance of the balance of intestinal flora. However, the underlying metabolic and regulatory mechanisms of these processes remain unclear. Our previous studies have shown that the LysR type transcriptional regulator of L.

Intermolecular 1,2-Difunctionalization of Alkenes Enabled by Fluoroamide-Directed Remote Benzyl C(sp)-H Functionalization.

A copper-catalyzed remote benzylic C-H functionalization strategy enabling 1,2-difunctionalization of alkenes with 2-methylbenzeneamides and nucleophiles, including alcohols, indoles, pyrroles, and the intrinsic amino groups, is reported, which is characterized by its redox-neutral conditions, exquisite site-selectivity, broad substrate scope, and wide utilizations of late-stage modifying bioactive molecules. This reaction proceeds through nitrogen-centered radical generation, hydrogen atom transfer, benzylic radical addition across the alkenes, single-electron oxidation, and carbocation electrophilic course cascades. While using external nucleophiles manipulates three-component alkene alkylalkoxylation and alkyl-heteroarylation with 2-methylbenzeneamides to access dialkyl ethers, 3-alkylindoles, and 3-alkylpyrroles, omitting the external nucleophiles results in two-component alkylamidation ([5+2] annulation) of alkenes with 2-methylbenzeneamides to benzo-[][1,2]thiazepine 1,1-dioxides.

Reasons for the differences in biotransformation of conjugated linoleic acid by Lactobacillus plantarum.

Conjugated linoleic acid (CLA) has attracted a great deal of attention for its functions in weight loss, regulation of metabolism, and antioxidant capabilities. Many microorganisms, including rumen bacteria, propionic acid bacilli, and Lactobacillus, have CLA biotransformation ability. The CLA production capability of different species is different, as are those different strains of the same species.

Single-plasmid systems based on CRISPR-Cas9 for gene editing in Lactococcus lactis.

Lactococcus lactis is a food-grade lactic acid bacterial species that is widely used in food and medical industries. Due to its relatively small genome and simple metabolism, L. lactis is commonly engineered to produce large quantities of recombinant proteins.

Recent Research Advances in Small Regulatory RNAs in Streptococcus.

Small non-coding RNAs (sRNAs) are a class of regulatory RNAs 20-500 nucleotides in length, which have recently been discovered in prokaryotic organisms. sRNAs are key regulators in many biological processes, such as sensing various environmental changes and regulating intracellular gene expression through binding target mRNAs or proteins. Bacterial sRNAs have recently been rapidly mined, thus providing new insights into the regulatory network of biological functions in prokaryotes.

High-efficiency transformation of Streptococcus thermophilus using electroporation.

Background: Streptococcus thermophilus, one of the most important lactic acid bacteria, is widely used in food fermentation, which is beneficial to improve food quality. However, the current genetic transformation systems are inefficient for S. thermophilus S-3, which hinders its further study.

Integrated analysis of gait parameters and gene expression profiles in a murine model of subarachnoid hemorrhage.

Gait analysis has been widely used to examine the behavioral presentation of numerous neurological disorders. Thorough murine model evaluation of the subarachnoid hemorrhage (SAH)-associated gait deficits is missing. This study measures gait deficits using a clinically relevant murine model of SAH to examine associations between gait variability and SAH-associated gene expressions.

LysR Family Regulator LttR Controls Production of Conjugated Linoleic Acid in Lactobacillus plantarum by Directly Activating the Operon.

Conjugated linoleic acids (CLAs) have attracted more attention as functional lipids due to their potential physiological activities, including anticancer, anti-inflammatory, anti-cardiovascular disease, and antidiabetes activities. Microbiological synthesis of CLA has become a compelling method due to its high isomer selectivity and convenient separation and purification processes. In , the generation of CLA from linoleic acids (LAs) requires the combination of CLA oleate hydratase (CLA-HY), CLA short-chain dehydrogenase (CLA-DH), and CLA acetoacetate decarboxylase (CLA-DC), which are separately encoded by -hy, -dh, and -dc.

Corrigendum: Hormone-Like Effects of 4-Vinylcyclohexene Diepoxide on Follicular Development.

[This corrects the article DOI: 10.3389/fcell.2020.

The second messenger c-di-AMP mediates bacterial exopolysaccharide biosynthesis: a review.

Cyclic dimeric adenosine 3'-5'-monophosphate (c-di-AMP) is a recently discovered nucleotide messenger in bacteria. It plays an important role in signaling, transcription, and cell physiology, such as in bacterial growth, potassium transport, fatty acid synthesis, the metabolic balance of cell wall components, and biofilm formation. Exopolysaccharides (EPSs) have distinct physico-chemical properties and diverse bioactivities including antibacterial, hypolipidemic, and antioxidative activities, and they are widely used in the food, pharmaceutical, and cosmetic industries.

Short communication: Genome-wide identification of new reference genes for reverse-transcription quantitative PCR in Streptococcus thermophilus based on RNA-sequencing analysis.

Streptococcus thermophilus, one of the most important industrial lactic acid bacteria, is widely used for the production of fermented dairy products such as yogurt and cheese. The accuracy of gene expression-based analyses (e.g.

Hormone-Like Effects of 4-Vinylcyclohexene Diepoxide on Follicular Development.

Background: 4-vinylcyclohexene diepoxide (VCD) has long been considered a hazardous occupational chemical that promotes ovarian failure. However, VCD is also used as a research compound to chemically induce animal models of premature ovarian insufficiency (POI), and in related work we unexpectedly found that VCD apparently exhibits both dose- and duration-dependent opposing, hormone-like effects on the maintenance of the primordial follicle pool, follicle development, and ovulation induction.

Results: We conducted experiments with cultured murine ovaries and performed transplantation experiments using postnatal day (PD) 2 and PD12 mice and found that low-dose, short-term exposure to VCD (VCD) actually protects the primordial/primary follicle pool and improves the functional ovarian reserve (FOR) by disrupting follicular atresia.

Visible light photoredox alkylazidation of alkenes with sodium azide and heteroarenium salts: entry to azido-containing 1,4-dihydropyridines.

A three-component alkene alkylazidation using sodium azide as the azido resource and heteroarenium salts as functionalized alkyl reagents for producing highly valuable 2-azido-1-(1,4-dihydropyridin-4-yl)-ethanes is described. This reaction allows the incorporation of both an azido group and a 1,4-dihydropyridin-4-yl group across C[double bond, length as m-dash]C bonds to construct two new bonds in a single reaction step, and represents a practical and mechanistically distinct alternative that harnesses an electrophilic heteroarenium ion to accomplish the alkene difunctionalization reaction.

Short communication: Dynamic changes in bacterial diversity during the production of powdered infant formula by PCR-DGGE and high-throughput sequencing.

Microorganisms such as thermophilic and psychrotrophic bacteria cause spoilage of milk and milk products [e.g., powdered infant formula (PIF)], mainly because they produce heat-stable extracellular enzymes.

Antrodin A from mycelium of Antrodia camphorata alleviates acute alcoholic liver injury and modulates intestinal flora dysbiosis in mice.

Ethnopharmacological Relevance: Antrodia camphorata (A. camphorata) is a rare functional fungus in Taiwan and contains a variety of biologically active ingredients. Antrodin A (AdA) is one of the main active ingredients in the solid-state fermented A.