7 results about "Coliform bacilli" patented technology

This invention discloses a recombinant *E. coli* strain for producing phenyllactic acid, a lactate dehydrogenase mutant, a whole-cell catalytic method for preparing phenyllactic acid, and the application of the aforementioned recombinant *E. coli* strain or lactate dehydrogenase mutant in the catalytic preparation of phenylpyruvic acid from phenyllactic acid. This invention significantly improves catalytic efficiency by modifying the 52nd amino acid of lactate dehydrogenase through site-directed mutagenesis. After mutating glutamine (Q) to valine (V) at position 52 of the *Lactobacillus mucosa* lactate dehydrogenase, the catalytic efficiency is significantly improved even at low cell density (OD). 600 =15) and substrate 15 g / L conditions, almost complete conversion was achieved; and combined with high-density catalysis and surface display optimization, the yield of phenyl lactic acid was increased while the downstream separation and purification costs were significantly reduced, greatly enhancing the potential for industrial production.

The application discloses a semi-chemical synthesis method of an N-terminal domain of matrix metalloproteinase inhibitor-2 (N-TIMP2) and application thereof. The N-TIMP2 is divided into three fragments, wherein a key tyrosine post-translational modification site is located in the fragment 2; the polypeptide resins of the fragment 1 and the fragment 2 are synthesized by using a solid-phase polypeptide synthesis technology, and the fragment 1 and the fragment 2 with a C-terminal hydrazide are obtained after cleavage, deprotection, extraction and purification; the fragment 3 is obtained by combining an E. coli recombinant expression technology and a three-step one-pot selective protection reaction of side chains of mercapto; the fragment 1, 2 connecting product is obtained through a first-step natural chemical connecting reaction; the full-length linear protein is obtained through a second-step natural chemical connecting reaction, desulfurization and deprotection; and finally, the N-TIMP2 protein is obtained through a refolding reaction. The semi-chemically synthesized N-TIMP2 protein has a comparable MMP-14 inhibiting activity to the N-TIMP2 protein obtained by using the E. coli recombinant expression technology.

This invention discloses a β-lactoglobulin mutant, its preparation method, and its application, relating to the field of genetic engineering technology. The amino acid sequence of the β-lactoglobulin mutant is shown in SEQ ID NO.1. The preparation method is as follows: designing forward primers, reverse primers, forward mutation primers, and reverse mutation primers; using wild-type β-Lg plasmid as a template, obtaining a mutant DNA fragment using overlap extension PCR technology; ligating the mutant DNA fragment into an empty vector and transforming it into competent E. coli cells for culture and identification to obtain a recombinant plasmid; transforming the recombinant plasmid into competent E. coli cells, culturing, lysing, collecting the cell supernatant, purifying, and obtaining the β-lactoglobulin mutant. This invention, through structural modification of β-lactoglobulin, improves its binding to specific IgE antibodies, enhances the immunogenicity of β-lactoglobulin allergens, and improves the sensitivity and specificity of its allergen-specific IgE antibody detection results.

This invention discloses a strain that produces high levels of L-homoserine, its construction method, and its applications, belonging to the field of amino acid fermentation. This invention provides a strain for efficient fermentation production of L-homoserine, its construction method, and its applications. This strain utilizes a cofactor homogenization scheme to introduce a heterologous NADH-dependent dehydrogenase to replace the original NADPH-dependent dehydrogenase in *E. coli*, thereby removing cofactor limitations, knocking out the main byproduct pathway, enhancing precursor supply, and strengthening efflux protein expression. Fed-batch fermentation in a fermenter achieves a yield as high as 155 g / L.

This invention discloses a polypeptide derived from human lactoferrin and its applications. This invention relates to the field of biotechnology, providing the application of the polypeptide or related biomaterials in the preparation of products with anti-inflammatory and soothing functions; the amino acid sequence of the polypeptide is shown in SEQ ID NO:1. The lactoferrin peptide of this invention can reduce the expression of the inflammatory factor IL-6 in cells, exhibiting anti-inflammatory and soothing effects. Simultaneously, this lactoferrin peptide has an inhibitory effect on the growth of Gram-negative and Gram-positive bacteria, represented by *Escherichia coli* and *Staphylococcus aureus*. This lactoferrin peptide shows promising application prospects in the preparation of drugs and cosmetics for the prevention and / or treatment of bacterial infectious diseases.

A whole-cell catalytic synthesis method for sialylated lactose-N-tetrasaccharide a includes the following steps: S1, constructing a recombinant engineered *E. coli* strain: using *E. coli* JM109(DE3) as the starting strain, the cytosine-5'-monophosphate-N-acetylneuraminic acid synthase gene neuA and / or the α-2,3-sialic transferase gene are expressed in free form to obtain a recombinant engineered *E. coli* strain; S2, whole-cell catalytic synthesis of LSTa: using sialic acid Neu5Ac and lactose-N-tetrasaccharide LNT as substrates, and IPTG as an inducer, the above-mentioned recombinant engineered *E. coli* strain and *Saccharomyces cerevisiae* as coupled fermentation strains are used for whole-cell catalytic synthesis of sialylated lactose-N-tetrasaccharide a. This whole-cell catalytic synthesis method achieves efficient synthesis of LSTa through the construction of an *E. coli* glycosyltransferase module and a *Saccharomyces cerevisiae* CTP energy regeneration module, with a yield as high as 38.03 g / L.