Exploration of Zero-Valent Iron Stabilized Calcium-Silicate-Alginate Beads' Catalytic Activity and Stability for Perchlorate Degradation.

Perchlorate contamination in groundwater poses a serious threat to human health, owing to its interference with thyroid function. The high solubility and poor adsorption of perchlorate ions make perchlorate degradation a necessary technology in groundwater contaminant removal. Here, we demonstrate the perchlorate degradation by employing nano zero-valent iron (nZVI) embedded in biocompatible silica alginate hybrid beads fabricated using calcium chloride (1 wt%) as a crosslinker.

Gaps-In-Noise Test Performance in Children with Speech Sound Disorder and Cognitive Difficulty.

Background And Objectives: The Gaps-In-Noise (GIN) test is a clinically effective measure of the integrity of the central auditory nervous system. The GIN procedure can be applied to a pediatric population above 7 years of age. The present study conducted the GIN test to compare the abilities of auditory temporal resolution among typically developing children, children with speech sound disorder (SSD), and children with cognitive difficulty (CD).

Simultaneous Determination of Etomidate and Its Major Metabolite, Etomidate Acid, in Urine Using Dilute and Shoot Liquid Chromatography-Tandem Mass Spectrometry.

Etomidate (ET) is a commonly used sedative-hypnotic agent such as propofol to induce anesthesia, and it is rapidly metabolized to etomidate acid (ETA) in liver. Herein, a simple method to determine ET and ETA in urine simultaneously was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A simple sample preparation method reduced the total analysis time.

Repetitive genomic insertion of gene-sized dsDNAs by targeting the promoter region of a counter-selectable marker.

Genome engineering can be used to produce bacterial strains with a wide range of desired phenotypes. However, the incorporation of gene-sized DNA fragments is often challenging due to the intricacy of the procedure, off-target effects, and low insertion efficiency. Here we report a genome engineering method enabling the continuous incorporation of gene-sized double-stranded DNAs (dsDNAs) into the Escherichia coli genome.

Biosynthesis of lactate-containing polyesters by metabolically engineered bacteria.

Due to increasing concerns about environmental problems, climate change and limited fossil resources, bio-based production of chemicals and polymers is gaining attention as one of the solutions to these problems. Polyhydroxyalkanoates (PHAs) are polyesters that can be produced by microbial fermentation. PHAs are synthesized using monomer precursors provided from diverse metabolic pathways and are accumulated as distinct granules inside the cells.

Tailor-made type II Pseudomonas PHA synthases and their use for the biosynthesis of polylactic acid and its copolymer in recombinant Escherichia coli.

Previously, we have developed metabolically engineered Escherichia coli strains capable of producing polylactic acid (PLA) and poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] by employing evolved Clostridium propionicum propionate CoA transferase (Pct(Cp)) and Pseudomonas sp. MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1(Ps6-19)). Introduction of mutations four sites (E130, S325, S477, and Q481) of PhaC1( Ps6-19) have been found to affect the polymer content, lactate mole fraction, and molecular weight of P(3HB-co-LA).

Efficient production of polylactic acid and its copolymers by metabolically engineered Escherichia coli.

Polylactic acid (PLA) is one of the promising biodegradable polymers, which has been produced in a rather complicated two-step process by first producing lactic acid by fermentation followed by ring opening polymerization of lactide, a cyclic dimer of lactic acid. Recently, we reported the production of PLA and its copolymers by direct fermentation of metabolically engineered Escherichia coli equipped with the evolved propionate CoA-transferase and polyhydroxyalkanoate (PHA) synthase using glucose as a carbon source. When employing these initially constructed E.

Metabolic engineering of Escherichia coli for the production of polylactic acid and its copolymers.

Polylactic acid (PLA) is a promising biomass-derived polymer, but is currently synthesized by a two-step process: fermentative production of lactic acid followed by chemical polymerization. Here we report production of PLA homopolymer and its copolymer, poly(3-hydroxybutyrate-co-lactate), P(3HB-co-LA), by direct fermentation of metabolically engineered Escherichia coli. As shown in an accompanying paper, introduction of the heterologous metabolic pathways involving engineered propionate CoA-transferase and polyhydroxyalkanoate (PHA) synthase for the efficient generation of lactyl-CoA and incorporation of lactyl-CoA into the polymer, respectively, allowed synthesis of PLA and P(3HB-co-LA) in E.