A genetically engineered strain having high-yield of L-valine is disclosed. Starting from Escherichia coli W3110, an acetolactate synthase gene alsS of Bacillus subtilis is inserted into a genome thereof and overexpressed; a ppGpp 3′-pyrophosphate hydrolase mutant R290E/K292D gene spoTM of Escherichia coli is inserted into the genome and overexpressed; a lactate dehydrogenase gene ldhA, a pyruvate formate lyase I gene pflB, and genes frdA, frdB, frdC, frdD of four subunits of fumaric acid reductase are deleted from the genome; a leucine dehydrogenase gene bcd of Bacillus subtilis replaces a branched chain amino acid transaminase gene ilvE of Escherichia coli; and an acetohydroxy acid isomeroreductase mutant L67E/R68F/K75E gene ilvCM replaces the native acetohydroxy acid isomeroreductase gene ilvC of Escherichia coli. Furthermore, the L-valine fermentation method is improved by using a two-stage dissolved oxygen control. The L-valine titer and the sugar-acid conversion rate are increased.

Improved production of threonine from E. coli by fermentation is accomplished by attenuation but not elimination of the expression of either or both of the yajV gene encoding omega-amidase (a.k.a. 2-oxoglutaramate amidase) and the ilvA gene encoding threonine dehydratase (a.k.a threonine deaminase). In cases where there is attenuated expression of the ilvA gene, there is no need to express an exogenous cimA gene. In examples of both cases, attenuation is accomplished by engineering these genes to contain a weaker ribosome site. Further improvements in threonine production are made by expression of a heterologous pyruvate carboxylase gene exemplified by expression of the Corynebacterium glutamicum pyc gene under control of an E. coli promoter, to provide expression of pyruvate carboxylase that is not naturally expressed in E. coli.

The disclosure provides recombinant bacterial host cells that metabolize and convert glycerol or volatile fatty acids (VFAs) to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV. The disclosure further provides methods of producing PHBV using the recombinant bacteria disclosed herein.

An Escherichia coli bacterial strain contains a gene encoding a recombinant protein and an open reading frame of i) a DNA fragment encoding an N-terminal signal peptide which mediates translocation of the protein into the periplasm, wherein the N-terminal signal peptide is an amino acid sequence with at least 80% correspondence in relation to SEQ ID No. 2 from amino acids 1 to 20 or is a signal peptide of lipoproteins Pal, NlpI, NlpB or OsmB of Escherichia coli, linked to ii) a following DNA sequence (lpp(N)) encoding a lipoprotein (Lpp(N)) which, compared to SEQ ID No. 2 from amino acids 21 to 78, is a different in at most ten amino acids and iii) a further DNA sequence (lpp(C)) encoding a lipoprotein (Lpp(C)) which, compared to SEQ ID No. 2 from amino acids 21 to 78, is a different in at most ten amino acids.

A bacterial strain suitable for expressing recombinant proteins contains an open reading frame which codes for a recombinant protein, under control of a functional promoter. The bacterial strain contains an open reading frame which codes for a muted peptidologycan-associated lipoprotein (PAL protein), under control of a functional promoter, wherein the PAL protein is muted such that it contains no membrane anchor for the outer cell membrane of the bacterial strain. A plasmid codes for a recombinant protein. Fermentative production of recombinant protein is facilitated by using the bacterial strain, with increased product yields in the culture residue without leading to a substantial die-off of the bacterial cells.

The present disclosure relates to synthetic biology and, in particular, the bioproduction of bakuchiol, and engineered enzymes for producing the same.

The present invention relates to delivering sample preparation technologies to enhance the performance of point-of-care agricultural diagnostics by improving the capacity to detect trace contaminations of pathogenic organisms along the entire food supply chain including pre- and post-harvest processing and distribution. Sample preparation is crucial for adequate test performance of downstream diagnostics like LAMP and supports sensitive detection of bacterial contaminates. This invention increases the speed and scale of routine pathogen surveillance and the efficacy of management response and mitigation of foodborne disease outbreaks.

The invention relates to the technical field of breast milk oligosaccharide production, and particularly to an Escherichia coli K-12 MG1655 BLBYZT6 and an application thereof. The Escherichia coli K-12 MG1655 BLBYZT6 is preserved in the China General Microbiological Culture Collection Center, with the collection number of CGMCC No. 28317, the collection date of Aug. 31, 2023, and the collection institution address of No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The Escherichia coli K-12 MG1655 BLBYZT6 of the invention is applied in fermentation production of 2-fucosyllactose and difucosyllactose. The invention improves a yield of the 2-fucosyllactose, reduces a dry matter proportion of a non-target product, realizes simple separation and purification, is beneficial for industrial production, and can co-produce the difucosyllactose with a purity greater than 90% at the same time.

An efficient synthesis and assembly method for the large fragment DNA based on the programmable nuclease Argonaute, specifically includes: constructing and treating antibiotic resistance gene reconstructed vectors with linearization, dividing a target DNA into multiple small DNA fragments and then synthesizing the small DNA fragments, followed by loading the synthesized small DNA fragments to the antibiotic resistance gene reconstructed vectors; and the SLIC and resistance gene reconstruction are used to achieve assembly of the target DNA. The method combines the SLIC with a resistance gene reconstruction strategy, allowing for the assembly of 5-6 small fragments in a single resistance gene reconstruction, which is more efficient and time-saving. Moreover, the number of the resistance gene reconstructions can be flexibly chosen according to the length of the DNA fragments. Mutations are not introduced caused by PCR, and the reconstructed large fragment do not need a second sequencing, saving time and costs.

An efficient synthesis and assembly method for the large fragment DNA based on the programmable nuclease Argonaute, specifically includes: constructing and treating antibiotic resistance gene reconstructed vectors with linearization, dividing a target DNA into multiple small DNA fragments and then synthesizing the small DNA fragments, followed by loading the synthesized small DNA fragments to the antibiotic resistance gene reconstructed vectors; and the SLIC and resistance gene reconstruction are used to achieve assembly of the target DNA. The method combines the SLIC with a resistance gene reconstruction strategy, allowing for the assembly of 5-6 small fragments in a single resistance gene reconstruction, which is more efficient and time-saving. Moreover, the number of the resistance gene reconstructions can be flexibly chosen according to the length of the DNA fragments. Mutations are not introduced caused by PCR, and the reconstructed large fragment do not need a second sequencing, saving time and costs.