A Convenient and Highly Efficient Strategy for Esterification of Poly (γ-Glutamic Acid) with Alkyl Halides at Room Temperature.

The presented work discusses the highly efficient esterification of poly (γ-glutamic acid) (γ-PGA) with alkyl halides at room temperature. The esterification reaction was completed within 3 h, and the prepared γ-PGA esters were obtained with excellent yields (98.6%) when 1,1,3,3-tetramethylguanidine (TMG) was used as a promoter.

Synthesis of Super-High-Viscosity Poly-γ-Glutamic Acid by -Deficient Strain of and Its Application in Microalgae Harvesting.

Poly-γ-glutamic acid (γ-PGA) is a natural polymer whose molecular weight and viscosity are critical for its application in various fields. However, research on super-high-molecular-weight or -viscosity γ-PGA is limited. In this study, the gene in WX-02 was knocked out using homologous recombination, and the batch fermentation performances of the recombinant strain WX-ΔpgdS were compared to those of WX-02.

Metabolic engineering of Bacillus licheniformis DW2 for ectoine production.

Ectoine is a high-value protective agent with extensive applications in the fields of fine chemicals and biopharmaceuticals, and it is naturally synthesized by Halomonas in extreme environment, however, the current production level cannot meet the growing market demand. In this study, we aimed to develop an efficient and environmentally friendly ectoine production process using Bacillus licheniformis as the host organism. Through introducing ectoine synthetase gene cluster ectABC from Halomonas elongate, as well as optimizing ectABC expression by promoter and 5'-UTR optimization, ectoine titer was increased to 0.

Developing a Bacillus licheniformis platform for de novo production of γ-aminobutyric acid and other glutamate-derived chemicals.

Microbial cell factories (MCFs) have emerged as a sustainable tool for the production of value-added biochemicals. However, developing high-performance MCFs remains a major challenge to fulfill the burgeoning demands of global markets. This study aimed to establish the B.

Exogenous Trehalose Assists in Resisting High-Temperature Stress Mainly by Activating Genes Rather than Entering Metabolism.

is a typical aroma-producing yeast in food brewing, but it has low heat resistance and poor proliferation ability at high temperature. Trehalose is generally considered to be a protective agent that helps stable yeast cells resist heat shock stress, but its functional mechanism for yeast cells in the adaptation period under heat stress is unclear. In this study, the physiological metabolism changes, specific gene transcription expression characteristics, and transcriptome differences of under different carbon sources under high-temperature stress (40 °C) were compared to explore the mechanism of trehalose inducing to recover and proliferate under high-temperature stress during the adaptation period.

Understanding energy fluctuation during the transition state: The role of AbrB in Bacillus licheniformis.

Background: Limited research has been conducted on energy fluctuation during the transition state, despite the critical role of energy supply in microbial physiological metabolism.

Results: This study aimed to investigate the regulatory function of transition state transcription factor AbrB on energy metabolism in Bacillus licheniformis WX-02. Firstly, the deletion of abrB was found to prolong the cell generation time, significantly reducing the intercellular ATP concentration and NADH/NAD ratio at the early stage.

Engineering Bacillus licheniformis as industrial chassis for efficient bioproduction from starch.

Starch is an attractive feedstock in biorefinery processes, while the low natural conversion rate of most microorganisms limits its applications. Herein, starch metabolic pathway was systematically investigated using Bacillus licheniformis DW2 as the host organism. Initially, the effects of overexpressing amylolytic enzymes on starch hydrolysis were evaluated.

Modular metabolic engineering of Bacillus amyloliquefaciens for high-level production of green biosurfactant iturin A.

As a kind of biosurfactants, iturin A has attracted people's wide attentions due to their features of biodegradability, environmentally friendly, etc.; however, high production cost limited its extensive application, and the aim of this research wants to improve iturin A production in Bacillus amyloliquefaciens. Firstly, dual promoter was applied to strengthen iturin A synthetase expression, and its yield was increased to 1.

Enhancement of alkaline protease production in recombinant Bacillus licheniformis by response surface methodology.

Alkaline protease is widely used in the food, detergent, and pharmaceutical industries because of its comparatively great hydrolysis ability and alkali tolerance. To improve the ability of the recombinant Bacillus licheniformis to produce alkaline protease, single-factor experiments and response surface methodology (RSM) were utilized to determine and develop optimal culture conditions. The results showed that three factors (corn starch content, soybean meal content, and initial medium pH) had significant effects on alkaline protease production (P < 0.

High Glucose Is a Stimulation Signal of the Salt-Tolerant Yeast on Thermoadaptive Growth.

The salt-tolerant yeast is a typical aroma-producing yeast used in food brewing, but its mechanism of high temperature tolerance is still unclear. In this study, the response mechanism of to glucose under high temperature stress at 40 °C was explored, based on the total synthetic lowest-nutrient medium. The results of the growth curves and scanning electron microscopy showed that high glucose was necessary for to restore growth under high temperature stress, with the biomass at 300 g/L of glucose (OD = 2.

Metabolic engineering of for efficient production of α-glucosidase inhibitor1-deoxynojirimycin.

Owing to the feature of strong α-glucosidase inhibitory activity, 1-deoxynojirimycin (1-DNJ) has broad application prospects in areas of functional food, biomedicine, etc., and this research wants to construct an efficient strain for 1-DNJ production, basing on HZ-12. Firstly, using the temperature-sensitive shuttle plasmid T2 (2)-Ori, gene in phosphotransferase system (PTS) was weakened by homologous recombination, and non-PTS pathway was strengthened by deleting its repressor gene , and 1-DNJ yield of resultant strain HZ-S2 was increased by 4.

A novel toolbox for precise regulation of gene expression and metabolic engineering in Bacillus licheniformis.

Despite industrial bio-manufacturing progress using Bacillus licheniformis, the absence of a well-characterized toolbox allowing precise regulation of multiple genes limits its expansion for basic research and application. Here, a novel gene expression toolbox (GET) was developed for precise regulation of gene expression and high-level production of 2-phenylethanol. Firstly, we established a novel promoter core region mosaic combination model to combine, characterize and analyze different core regions.

Microbial synthesis of bacitracin: Recent progress, challenges, and prospects.

Microorganisms are important sources of various natural products that have been commercialized for human medicine and animal healthcare. Bacitracin is an important antibacterial natural product predominantly produced by and , and it is characterized by a broad antimicrobial spectrum, strong activity and low resistance, thus bacitracin is extensively applied in animal feed and veterinary medicine industries. In recent years, various strategies have been proposed to improve bacitracin production.

[Efficient production of L-asparaginase in by optimizing expression elements and host].

L-asparaginase (L-ASN) is widely applied in the treatment of malignant tumor and low-acrylamide food production, however, the low expression level hampers its application. Heterologous expression is an effective strategy to increase the expression level of target enzymes, and is generally used as the host for efficient production of enzymes. In this study, the expression level of L-asparaginase in was enhanced through optimization of expression element and host.

Enhancing the activity of disulfide-bond-containing proteins via promoting disulfide bond formation in Bacillus licheniformis.

Disulfide bonds in proteins have strongly influence on the folding efficiency by constraining the conformational space. The inefficient disulfide bond formation of proteins is the main limiting factor of enzyme activity and stability. This study aimed to increase the activity of disulfide-bond-containing proteins via promoting disulfide bonds formation in Bacillus licheniformis.

Modular Engineering to Enhance Keratinase Production for Biotransformation of Discarded Feathers.

Biotransformation of wasted feathers via feather-degrading enzyme has gained immense popularity, low conversion efficiency hinders its scale application, and the main purpose of this study is to improve feather-degrading enzyme production in Bacillus licheniformis. Firstly, keratinase from Bacillus amyloliquefaciens K11 was attained with the best performance for feather hydrolysis, via screening several extracellular proteases from Bacillus; also, feather powder was proven as the most suitable substrate for determination of feather-degrading enzyme activity. Then, expression elements, including signal peptides and promoters, were optimized, and the combination of signal peptide SP with promoter Pdual3 owned the best performance, keratinase activity aggrandized by 6.

Minimization and optimization of α-amylase terminator for heterologous protein production in Bacillus licheniformis.

Terminators serve as the regulatory role in gene transcription termination; however, few researches about terminator optimization have been conducted, which leads to the lack of available and universal terminator for gene expression regulation in Bacillus. To solve this problem and expand synthetic biology toolbox of Bacillus licheniformis, the terminator T1 of endogenous α-amylase gene (amyL) was characterized in this research, with a termination efficiency of 87.81%.

Enhanced production of iturin A by strengthening fatty acid synthesis modules in .

Iturin A is a biosurfactant with various applications, and its low synthesis capability limits its production and application development. Fatty acids play a critical role in cellular metabolism and target product syntheses, and the relationship between fatty acid supplies and iturin A synthesis is unclear. In this study, we attempted to increase iturin A production strengthening fatty acid synthesis pathways in .

Combined metabolic analyses for the biosynthesis pathway of l-threonine in .

Currently, industrial production of l-threonine (Thr) is based on direct fermentation with microorganisms such as , which has the characteristics of low cost and high productivity. In order to elucidate the key metabolic features of the synthesis pathway of Thr in to provide clues for metabolic regulation or engineering of the strain, this study was carried out on an l-threonine over-producing strain, in terms of analyses of metabolic flux, enzyme control and metabonomics. Since environmental disturbance and genetic modification are considered to be two important methods of metabolic analysis, addition of phosphate in the media and comparison of strains with different genotypes were selected as the two candidates due to their significant influence in the biosynthesis of Thr.

Genetic and metabolic engineering for poly-γ-glutamic acid production: current progress, challenges, and prospects.

Accompanied with the developments of gene editing and synthetic biology toolkits, various metabolic engineering strategies have been established for strain improvement to enhance the target metabolite production. Poly-γ-glutamic acid (γ-PGA) is a natural biopolymer that mainly produced by Bacillus, and low-level yield hinders its application. To address this problem, numerous approaches have been conducted to increase γ-PGA yield.

Enhanced production of poly-γ-glutamic acid via optimizing the expression cassette of hemoglobin in .

Poly-γ-glutamic acid (γ-PGA) is a natural polymer with various applications, and its high-viscosity hinders oxygen transmission and improvement of synthesis level. hemoglobin (VHB) has been introduced into various hosts as oxygen carrier, however, its expression strength and contact efficiency with oxygen hindered efficient oxygen transfer and metabolite synthesis. Here, we want to optimize the expression cassette of VHB for γ-PGA production.

Multilevel metabolic engineering of Bacillus licheniformis for de novo biosynthesis of 2-phenylethanol.

Due to its pleasant rose-like scent, 2-phenylethanol (2-PE) has been widely used in the fields of cosmetics and food. Microbial production of 2-PE offers a natural and sustainable production process. However, the current bioprocesses for de novo production of 2-PE suffer from low titer, yield, and productivity.

Rational engineering of cofactor specificity of glutamate dehydrogenase for poly-γ-glutamic acid synthesis in Bacillus licheniformis.

Poly-γ-glutamic acid (γ-PGA) is a multifunctional biopolymer mainly produced by Bacillus. The cofactor specificity of enzymes plays a critical role in regulating metabolic process and metabolite production. Here, we present a novel approach for switching cofactor specificity of glutamate dehydrogenase RocG from nicotinamide adenine dinucleotide phosphate (NADPH) to nicotinamide adenine dinucleotide (NADH) to improve γ-PGA production.

[Metabolic engineering of L-cysteine supply modules for enhanced production of bacitracin in Bacillus licheniformis].

Bacitracin is a broad-spectrum antibiotics mainly produced by Bacillus, and is used as veterinary medicine in the fields of livestock and poultry breeding. Insufficient supply of precursor amino acids might be an important factor that hinders high-level microbial production of bacitracin. We investigated the effect of strengthening L-cysteine supply on bacitracin production by an industrial bacitracin producer, Bacillus licheniformis DW2.