8results about How to "Clear genetic background" patented technology

The invention discloses a construction method and application of a chlamydomonas reinhardtii source high-sweetness induced protein variant engineering algal strain. The preparation method comprises the following steps: firstly, modifying and optimizing protein coding sequences of sweet taste induction proteins Miraculin and Neoculin, so as to obtain optimized gene sequences of CrMiraculin and CrNeoculin; the method comprises the following steps: firstly, preparing a Chlamydomonas reinhardtii strain, then cloning the Chlamydomonas reinhardtii strain into an expression vector pGM6, constructing a recombinant expression vector, introducing the recombinant expression vector into the Chlamydomonas reinhardtii wild strain, and screening by using a paromomycin resistance marker carried by the vector to obtain a transformed strain. The obtained engineering algal strain can stably inherit and efficiently express the target sweet induced protein, and the chlamydomonas reinhardtii algal powder rich in the CrMiraculin and CrNeoculin sweet induced protein is obtained by performing fermentation culture on the engineering algal strain. Finally, through protein purification and mixing with acidic substances, sour taste can be induced to be converted into sweet taste, so that the method has great application potential in the fields of foods, seasonings or health-care products.

The invention provides a retina photosensitive neuronal lesion zebrafish model and a construction method thereof, and relates to the technical field of gene engineering. Wherein the sgRNA comprises a guide sequence which can specifically recognize and be combined with a nucleotide sequence shown as SEQ ID NO.4 in an elovl2 gene. The high specificity of the sgRNA ensures the precise targeted modification of the elovl2 gene, and obviously reduces the off-target risk. The genetic background of the constructed zebrafish model is clear, and the retinopathy phenotype can be reliably attributed to the lovl2 gene mutation, so that a stable biological tool which is highly similar to human diseases is provided for related disease research and drug screening.

This invention discloses an intelligent programmed engineered probiotic system and its preparation method. The system uses probiotic strains as the engineered substrate bacteria, and is constructed by integrating the coding genes for superoxide dismutase (SOD), antimicrobial peptides (AMP), and a synchronized cleavage circuit (SLC) with the probiotic strains through genetic engineering technology. This invention also discloses a pH-responsive genetically engineered bacterial microsphere containing the aforementioned intelligent programmed engineered probiotic system, which is encapsulated in a carrier formed by the cross-linking reaction of sodium alginate and calcium chloride ions. The intelligent programmed engineered probiotic system and the accompanying pH-responsive genetically engineered bacterial microspheres constructed in this invention, through the synergistic design of the dual-function therapeutic modules SOD and AMP, and the programmed cleavage circuit SLC, simultaneously address the three core problems of IBD: oxidative stress, dysbiosis, and intestinal barrier damage.

This invention relates to the fields of microbial fermentation and genetic engineering technology, specifically disclosing a method for preparing human type III collagen fragments. Based on Pichia pastoris, this invention constructs a multidimensional synergistic expression system of "molecular chaperone co-expression - precursor supply - osmotic pressure adaptation regulation," reducing the structural instability of collagen fragments during secretion and post-processing, and constructing an expression system suitable for stable and efficient secretion of collagen fragments. The method described in this invention can achieve efficient extracellular secretory expression of human type III collagen fragments, and the obtained protein has high structural uniformity and stability, with a protein yield of up to 6.55 g / L under 5 L fermenter conditions. The method described in this invention is suitable for the large-scale preparation of human type III collagen fragments and provides a new technical solution for obtaining collagen products with high structural uniformity and good functional activity.

The invention provides an L-alanine production strain and a construction method and application thereof.The L-alanine production strain is characterized in that a dns gene, a vnp1 gene and a vnp2 gene in a genome of vibrio natriureticus are sequentially knocked out through gene modification with the vibrio natriureticus as an original strain, a series of key competitive pathway genes pflB, lldh, dldh, pta, ackA and adhE are knocked out in order to block an organic acid fermentation pathway of the vibrio natriureticus, and the vibrio natriureticus is obtained; the production of L-alanine is increased, the accumulation of organic acids is reduced, pXtuf-alaD plasmids are transferred to increase the gene copy number, and by cooperating with the ultrafast growth characteristic of the starting strain vibrio natriureticus, the constructed strain has a clear genetic background, shows efficient transformation ability in the subsequent anaerobic production stage, can efficiently produce L-alanine, and has a wide application prospect. Good industrial application prospects are realized.

The present application relates to a kind of plasmid for endowing bacillus to degrade skatole function and its application, belong to agricultural environment microorganism and genetic engineering technical field, to solve the existing skatole management high cost, easy to produce secondary pollution, part of degradation strain exists biological safety risk, and the genetic element of natural degradation strain is difficult to cross-strain application problem.The present application discloses the plasmid of nucleotide sequence as shown in SEQ ID NO.1, by the plasmid is transformed into bacillus competent cell, is cultivated in M9 solid medium containing skatole and positive clone detection obtains recombination bacillus, it is inoculated with 0.5% to 5% inoculation amount in the medium containing 0.05 to 0.2g / L skatole, under the condition of 30 to 37 DEG C, 120 to 250rpm 4 to 48h can be degraded skatole.The present application is mainly used for the skatole deodorization of breeding manure and the like scene, provides safe controllable, efficient and scalable biological technology scheme.

The invention relates to the field of biotechnology and biological products, in particular to a bordetella bronchiseptica attenuated strain and application thereof. The bordetella bronchiseptica low virulent strain which is remarkably weakened in virulence and keeps high immunogenicity is obtained in a continuous passage and genome sequencing mode, the remarkable virulence weakening characteristic is shown, dog diseases cannot be caused, and the high immunogenicity is achieved. The low virulent strain is used for preparing a bordetella bronchiseptica vaccine, can efficiently stimulate the specific immune response of dog and cat organisms, reduces the repeated inoculation frequency, and avoids the environmental transmission risk of toxic strains from the source. The screened Bordetella bronchiseptica attenuated strain does not contain any exogenous nucleic acid, the genetic background of the strain is clear and traceable, the biological safety requirement of veterinary vaccines is completely met, and a safe and reliable brand-new scheme is provided for dog and cat health protection.

This invention relates to a method and its application for enhancing the synthesis of serotonin and melatonin in *Escherichia coli*, belonging to the field of genetic engineering technology. This invention achieves the following results through the heterologous expression of high-yield serotonin and melatonin compounds Tph, Tdc, SNAT, and COMT in *Escherichia coli*, and through enzyme engineering, metabolic engineering, transport protein engineering, and reaction condition optimization: the optimized yield of serotonin synthesized from tryptophan reaches 1.92 g / L; the yield of melatonin synthesized from tryptophan reaches 3.40 g / L.