11 results about "LacZ Genes" patented technology

The invention relates to Escherichia coli for producing 2 '-fucosyllactose as well as a construction method and application of the Escherichia coli, and belongs to the technical field of genetic engineering. A CRISPR / Cas9 system is used for transforming a genome of escherichia coli MG1655, a wcaJ gene and a lacZ gene are knocked out, the utilization rate of lactose and GDP-L-fucose in a metabolic pathway is increased, a promoter of a lacY gene is replaced with PJ23119, an alpha-1, 2-fucosyltransferase mutant with a dissolution promoting tag GST added to the N end is heterologously introduced, the expression quantity of the alpha-1, 2-fucosyltransferase mutant is increased through multi-copy integration, and the expression quantity of the alpha-1, 2-fucosyltransferase mutant is increased. Meanwhile, a gmd gene, an fcl gene, a manB gene and a manC gene are co-expressed at proper sites, so that the synthesis route of the GDP-L-fucose is optimized. The strain obtained through transformation can efficiently convert lactose into 2 '-FL and has the advantages of being low in metabolic burden, sufficient in precursor supply, high in enzyme stability and the like, the construction method is clear in step and suitable for industrial production, the yield of 2'-FL can be remarkably increased through microbial agents and fermentation application, and the production cost is reduced.

The invention relates to a polynucleotide comprising a lacZ gene (lacZFS) encoding a β-galactosidase characterized by a particular profile with respect to its lactose hydrolysis efficiency. The invention also relates to a strain of Streptococcus thermophilus comprising a lacZFS allele and a bacterial composition thereof, and its use for obtaining fermented milk that does not undergo subsequent acidification.

The invention relates to a polynucleotide comprising a lacZ gene (lacZFS) encoding a β-galactosidase characterized by a particular profile regarding its efficiency of hydrolysis of lactose. The invention is also directed to a Streptococcus thermophilus strain comprising a lacZFS allele and bacterial composition thereof, and their use to obtain fermented milk not undergoing post-acidification.

This invention relates to the field of bioengineering, and more particularly to genomes, expression cassettes, expression vectors, recombinant strains, and their applications. The invention provides a genome including the NGF gene, the malF gene, and the lacZ gene. This invention provides a reliable and efficient system and method for expressing and screening disulfide bond-rich proteins, which not only has broad application prospects in the expression of disulfide bond-rich proteins, but also provides new ideas and methods for research and applications in related fields.

The invention discloses a biosynthesis method of alpha-lipoic acid, an engineering strain and a preparation method of the engineering strain. The construction of the engineering strain comprises the following steps: transforming lipocaprylamide enzyme Lpa of enterococcus faecalis, constructing the lipocaprylamide enzyme Lpa to an arabinose promoter or a Cold temperature-sensitive promoter, and then replacing the lipocaprylamide enzyme Lpa to a LacZ gene and an lpxM gene of escherichia coli through RED recombination; or the genes of LipD, lplA, lipA and lpA which are subjected to gene code modification are expressed in the saccharomyces cerevisiae through a pESC vector. The engineering strain is cultured to biologically synthesize alpha-lipoic acid, so that the fermentation cost is further reduced, cyclic synthesis is realized, and the yield is greatly increased.

The invention relates to a polynucleotide comprising a lacZ gene (lacZFS) encoding a β-galactosidase characterized by a particular profile regarding its efficiency of hydrolysis of lactose. The invention is also directed to a Streptococcus thermophilus strain comprising a lacZFS allele and bacterial composition thereof, and their use to obtain fermented milk not undergoing post-acidification.

The invention provides a T vector plasmid fused with a Lacz gene and suitable for blue-white spot screening and preparation of the T vector plasmid, and belongs to the field of cloning vectors, and a preparation method of the T vector plasmid comprises the steps that a plasmid containing the Lacz gene serves as a starting plasmid, a gene segment with two XcmI restriction enzyme cutting sites is fused into the Lacz gene, and then a target plasmid is obtained. The T vector plasmid provided by the invention is extremely simple and convenient to use, when the plasmid is applied to T vector clone construction, only white colonies need to be selected for PCR verification, a large number of positive clones can be screened, the preparation cost of a single transformation vector can be reduced to 0.15 yuan per time and is far lower than that of an existing commercial T vector, and the T vector has extremely high commercial value.

This invention provides genetically modified bacteria that produce L-valine, as well as a method for constructing and using such bacteria. By knocking out the yjiT gene of E. coli to express brnF and brnE, knocking out the yjiV gene to express ilvE and ilvD, knocking out the trpR gene to express the ilvH mutant protein, knocking out the lacI and lacZ genes to express DNA polymerase, and / or knocking out the ycgH gene to express ilvC, the resulting genetically modified bacteria can increase L-valine production. These genetically modified bacteria can be used for L-valine production and have promising application prospects.

This invention discloses an engineered serotonin-producing strain and its applications. The strain has an insertion of a tryptophan hydroxylase (TPH1) gene expression sequence and a tryptophan deacidase (tdc) gene expression sequence into its chromosome. The TPH1 gene expression sequence is inserted at the lacZ gene locus, with a size of 2000-3000 bp, and the tdc gene expression sequence is inserted at the malEK gene locus, with a size of 1500-3000 bp. This engineered strain grows well and can stably express the target genes. In particular, the insertion of the humanized tryptophan hydroxylase (TPH1) gene and the rice tryptophan deacidase (tdc(R)) gene into *E. coli* with the tnaA gene knocked out significantly increases 5-HT production to 82 mg / L. The engineered serotonin-producing strain provided by this invention shows broad application prospects in improving intestinal dysfunction and / or anxiety-depression-like behaviors.

The invention provides a promoter and a screening method and application thereof. The promoter is obtained through a screening method based on a lacZ gene. Specifically, the method comprises the following steps: respectively carrying out library establishment and preliminary screening on plasmids which contain beta-galactosidase genes (lacZ or lacZ alpha genes) and have inactivated promoters, and then carrying out secondary screening on the basis of a chromogenic reaction and enzyme activity determination between a chromogenic substrate and beta-galactosidase, so as to obtain the promoter with required strength. According to the technical scheme, the screening process is simplified, the screening efficiency is improved, and a new thought and a new tool are provided for research and application of the promoter.

This invention relates to the field of biotechnology, specifically disclosing a cell-free protein expression system (CFS), its applications, and a kit. The CFS comprises: 35-50 vol% *E. coli* cell extract, 40-50 vol% lysis buffer, 8-12 vol% gene template, and 2-15 vol% nuclease-free water; wherein the *E. coli* is a recombinant bacterium obtained by modifying a recipient *E. coli*, the modification including: (1) knocking out the LacZ gene in the recipient *E. coli*; and (2) adding the LyseR gene to the recipient *E. coli*. The CFS of this invention features high expression activity and gene stability, making it suitable for expressing high molecular weight proteins and for in vitro diagnostic applications based on cell-free sensors.