Inducible engineering precursor metabolic flux for synthesizing hyaluronic acid of customized molecular weight in Streptococcus zooepidemicus.

Background: Hyaluronic acid (HA) is extensively employed in various fields such as medicine, cosmetics, food, etc. The molecular weight (MW) of HA is crucial for its biological functions. Streptococcus zooepidemicus, a prominent HA industrial producer, naturally synthetizes HA with high MW.

Improving glucose oxidase catalysis in Aspergillus niger via Vitreoscilla hemoglobin fusion protein.

Oxygen is crucial for converting glucose to gluconic acid catalyzed by glucose oxidase (Gox). However, industrial gluconic acid production faces oxygen supply limitations. To enhance Gox efficiency, Vitreoscilla hemoglobin (VHb) has been considered as an efficient oxygen transfer carrier.

Engineering a Phosphoketolase Pathway to Supplement Cytosolic Acetyl-CoA in Enables a Significant Increase in Citric Acid Production.

Citric acid is widely used in the food, chemical and pharmaceutical industries. is the workhorse used for citric acid production in industry. A canonical citrate biosynthesis that occurred in mitochondria was well established; however, some research suggested that the cytosolic citrate biosynthesis pathway may play a role in this chemical production.

Effective production of kojic acid in engineered Aspergillus niger.

Background: Kojic acid (KA) is a widely used compound in the cosmetic, medical, and food industries, and is typically produced by Aspergillus oryzae. To meet increasing market demand, it is important to optimize KA production through seeking alternatives that are more economic than current A. oryzae-based methods.

Improved genetic transformation by disarmament of type II Restriction-Modification system in .

Unlabelled: , group C Streptococci, is currently used for the industrial production of hyaluronic acid (HA). However, genetic manipulation of is severely limited by its low transformation efficiency, which might be in part due to the Restriction-Modification (R-M) systems. The complete genome sequence of ATCC39920 revealed the presence of two putative R-M systems, type I and type II.

Is hyaluronic acid production transcriptionally regulated? A transcriptional repressor gene deletion study in Streptococcus zooepidemicus.

Hyaluronic acid (HA) is a multiple-function biopolymer that is widely used in food, cosmetic, and biomedical fields. In group C streptococci, the major workhorse of HA production in industry, the HA biosynthetic pathway has been proposed, while how HA synthesis is regulated is unclear. In this study, we identified twenty-five putative transcriptional repressors in S.

Engineering of a genome-reduced strain Bacillus amyloliquefaciens for enhancing surfactin production.

Background: Genome reduction and metabolic engineering have emerged as intensive research hotspots for constructing the promising functional chassis and various microbial cell factories. Surfactin, a lipopeptide-type biosurfactant with broad spectrum antibiotic activity, has wide application prospects in anticancer therapy, biocontrol and bioremediation. Bacillus amyloliquefaciens LL3, previously isolated by our lab, contains an intact srfA operon in the genome for surfactin biosynthesis.

Development of an efficient pathway construction strategy for rapid evolution of the biodegradation capacity of Pseudomonas putida KT2440 and its application in bioremediation.

In this work, we developed an efficient pathway construction strategy, consisting of DNA assembler-assisted pathway assembly and counterselection system-based chromosomal integration, for the rapid and efficient integration of synthetic biodegradation pathways into the chromosome of Pseudomonas putida KT2440. Using this strategy, we created a novel degrader capable of complete mineralization of γ-hexachlorocyclohexane (γ-HCH) and 1,2,3-trichloropropane (TCP) by integrating γ-HCH and TCP biodegradation pathways into the chromosome of P. putida KT2440.

Deletion of genomic islands in the Pseudomonas putida KT2440 genome can create an optimal chassis for synthetic biology applications.

Background: Genome streamlining is a feasible strategy for constructing an optimum microbial chassis for synthetic biology applications. Genomic islands (GIs) are usually regarded as foreign DNA sequences, which can be obtained by horizontal gene transfer among microorganisms. A model strain Pseudomonas putida KT2440 has broad applications in biocatalysis, biotransformation and biodegradation.

An order-aware scheme for robust direction of arrival estimation in the spherical harmonic domain.

Direction of arrival (DOA) estimation of sound sources using a spherical microphone array is usually performed in the spherical harmonic (SH) domain. In a non-noisy environment, it suffices to use only the zeroth- and first-order spherical harmonic beams (SHBs) in the SH domain for DOA estimation. One such method is based on the pseudo-intensity vector (PIV), which is attractive due to its low computational complexity.

Metabolic engineering of Bacillus amyloliquefaciens LL3 for enhanced poly-γ-glutamic acid synthesis.

Poly-γ-glutamic acid (γ-PGA) is a biocompatible and biodegradable polypeptide with wide-ranging applications in foods, cosmetics, medicine, agriculture and wastewater treatment. Bacillus amyloliquefaciens LL3 can produce γ-PGA from sucrose that can be obtained easily from sugarcane and sugar beet. In our previous work, it was found that low intracellular glutamate concentration was the limiting factor for γ-PGA production by LL3.

Enhanced production of antifungal lipopeptide iturin A by Bacillus amyloliquefaciens LL3 through metabolic engineering and culture conditions optimization.

Background: Iturins, which belong to antibiotic cyclic lipopeptides mainly produced by Bacillus sp., have the potential for application in biomedicine and biocontrol because of their hemolytic and antifungal properties. Bacillus amyloliquefaciens LL3, isolated previously by our lab, possesses a complete iturin A biosynthetic pathway as shown by genomic analysis.

Screening of endogenous strong promoters for enhanced production of medium-chain-length polyhydroxyalkanoates in Pseudomonas mendocina NK-01.

Polyhydroxyalkanoate (PHA) can be produced by microorganisms from renewable resources and is regarded as a promising bioplastic to replace petroleum-based plastics. Pseudomonas mendocina NK-01 is a medium-chain-length PHA (mcl-PHA)-producing strain and its whole-genome sequence is currently available. The yield of mcl-PHA in P.

Morphology engineering for enhanced production of medium-chain-length polyhydroxyalkanoates in Pseudomonas mendocina NK-01.

Polyhydroxyalkanoates (PHAs) can be produced by microorganisms from renewable resources and are regarded as promising bioplastics to replace petroleum-based plastics. A medium-chain-length PHAs (mcl-PHA)-producing strain Pseudomonas mendocina NK-01 was isolated previously by our lab and its whole-genome sequence is currently available. Morphology engineering of manipulating cell morphology-related genes has been applied for enhanced accumulation of the intracellular biopolymer short-chain-length PHAs (scl-PHA).

Regulation of bacteria population behaviors by AI-2 "consumer cells" and "supplier cells".

Background: Autoinducer-2 (AI-2) is a universal signal molecule and enables an individual bacteria to communicate with each other and ultimately control behaviors of the population. Harnessing the character of AI-2, two kinds of AI-2 "controller cells" ("consumer cells" and "supplier cells") were designed to "reprogram" the behaviors of entire population.

Results: For the consumer cells, genes associated with the uptake and processing of AI-2, which includes LsrACDB, LsrFG, LsrK, were overexpressed in varying combinations.

Combinatorial metabolic engineering of Pseudomonas putida KT2440 for efficient mineralization of 1,2,3-trichloropropane.

An industrial waste, 1,2,3-trichloropropane (TCP), is toxic and extremely recalcitrant to biodegradation. To date, no natural TCP degraders able to mineralize TCP aerobically have been isolated. In this work, we engineered a biosafety Pseudomonas putida strain KT2440 for aerobic mineralization of TCP by implantation of a synthetic biodegradation pathway into the chromosome and further improved TCP mineralization using combinatorial engineering strategies.

Construction of energy-conserving sucrose utilization pathways for improving poly-γ-glutamic acid production in Bacillus amyloliquefaciens.

Background: Sucrose is an naturally abundant and easily fermentable feedstock for various biochemical production processes. By now, several sucrose utilization pathways have been identified and characterized. Among them, the pathway consists of sucrose permease and sucrose phosphorylase is an energy-conserving sucrose utilization pathway because it consumes less ATP when comparing to other known pathways.

Enhancing poly-γ-glutamic acid production in Bacillus amyloliquefaciens by introducing the glutamate synthesis features from Corynebacterium glutamicum.

Background: Poly-γ-glutamic acid (γ-PGA) is a valuable polymer with glutamate as its sole precursor. Enhancement of the intracellular glutamate synthesis is a very important strategy for the improvement of γ-PGA production, especially for those glutamate-independent γ-PGA producing strains. Corynebacterium glutamicum has long been used for industrial glutamate production and it exhibits some unique features for glutamate synthesis; therefore introduction of these metabolic characters into the γ-PGA producing strain might lead to increased intracellular glutamate availability, and thus ultimate γ-PGA production.

Improvement of levan production in Bacillus amyloliquefaciens through metabolic optimization of regulatory elements.

Levan is a functional homopolymer of fructose with considerable applications in food, pharmaceutical and cosmetic industries. To improve the levan production in Bacillus amyloliquefaciens, the regulatory elements of sacB (encoding levansucrase) expression and levansucrase secretion were optimized. Four heterologous promoters were evaluated for sacB expression, and the Pgrac promoter led to the highest level for both sacB transcription and levansucrase enzyme activity.

Mutations in genes encoding antibiotic substances increase the synthesis of poly-γ-glutamic acid in Bacillus amyloliquefaciens LL3.

Poly-γ-glutamic acid (γ-PGA) is an important natural biopolymer that is used widely in fields of foods, medicine, cosmetics, and agriculture. Several B. amyloliquefaciens LL3 mutants were constructed to improve γ-PGA synthesis via single or multiple marker-less in-frame deletions of four gene clusters (itu, bae, srf, and fen) encoding antibiotic substances.

Effects of MreB paralogs on poly-γ-glutamic acid synthesis and cell morphology in Bacillus amyloliquefaciens.

Actin-like MreB paralogs play important roles in cell shape maintenance, cell wall synthesis and the regulation of the D,L-endopeptidases, CwlO and LytE. The gram-positive bacteria, Bacillus amyloliquefaciens LL3, is a poly-γ-glutamic acid (γ-PGA) producing strain that contains three MreB paralogs: MreB, Mbl and MreBH. In B.

Improved poly-γ-glutamic acid production in Bacillus amyloliquefaciens by modular pathway engineering.

A Bacillus amyloliquefaciens strain with enhanced γ-PGA production was constructed by metabolically engineering its γ-PGA synthesis-related metabolic networks: by-products synthesis, γ-PGA degradation, glutamate precursor synthesis, γ-PGA synthesis and autoinducer synthesis. The genes involved in by-products synthesis were firstly deleted from the starting NK-1 strain. The obtained NK-E7 strain with deletions of the epsA-O (responsible for extracellular polysaccharide synthesis), sac (responsible for levan synthesis), lps (responsible for lipopolysaccharide synthesis) and pta (encoding phosphotransacetylase) genes, showed increased γ-PGA purity and slight increase of γ-PGA titer from 3.

Recruiting a new strategy to improve levan production in Bacillus amyloliquefaciens.

Microbial levan is an important biopolymer with considerable potential in food and medical applications. Bacillus amyloliquefaciens NK-ΔLP strain can produce high-purity, low-molecular-weight levan, but production is relatively low. To enhance the production of levan, six extracellular protease genes (bpr, epr, mpr, vpr, nprE and aprE), together with the tasA gene (encoding the major biofilm matrix protein TasA) and the pgsBCA cluster (responsible for poly-γ-glutamic acid (γ-PGA) synthesis), were intentionally knocked out in the Bacillus amyloliquefaciens NK-1 strain.

Construction of a Bacillus amyloliquefaciens strain for high purity levan production.

Bacillus amyloliquefaciens NK-1 has the potential to produce levan and poly-gamma-glutamic acid (γ-PGA) simultaneously. However, it is not possible to purify each single product from the same strain because the extraction process is identical. We deleted the pgs cluster (for γ-PGA synthesis) from the NK-1 strain and constructed a γ-PGA-deficient NK-ΔLP strain.

Deletion of genes involved in glutamate metabolism to improve poly-gamma-glutamic acid production in B. amyloliquefaciens LL3.

Here, we attempted to elevate poly-gamma-glutamic acid (γ-PGA) production by modifying genes involved in glutamate metabolism in Bacillus amyloliquefaciens LL3. Products of rocR, rocG and gudB facilitate the conversion from glutamate to 2-oxoglutarate in Bacillus subtillis. The gene odhA is responsible for the synthesis of a component of the 2-oxoglutarate dehydrogenase complex that catalyzes the oxidative decarboxylation of 2-oxoglutarate to succinyl coenzyme A.