302 results about "Wild type strain" patented technology

The present invention relates to novel rumen bacterial mutants resulted from the disruption of a lactate dehydrogenase gene (ldhA) and a pyruvate formate-lyase gene (pfl) (which are involved in the production of lactic acid, formic acid and acetic acid) from rumen bacteria; a novel bacterial mutant (Mannheimia sp. LPK7) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl), a phosphotransacetylase gene (pta), and a acetate kinase gene (ackA); a novel bacterial mutant (Mannheimia sp. LPK4) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl) and a phosphoenolpyruvate carboxylase gene (ppc) involved in the immobilization of CO2 in a metabolic pathway of producing succinic acid; and a method for producing succinic acid, which is characterized by the culture of the above mutants in anaerobic conditions. The inventive bacterial mutants have the property of producing succinic acid at high concentration while producing little or no organic acids, as compared to the prior wild-type strains of producing various organic acids. Thus, the inventive bacterial mutants are useful as strains for the industrial production of succinic acid.

An engineered nitrile hydratase-producing bacterium and its construction method as well as its applications, wherein the engineered nitrile hydratase-producing bacterium is a mutant strain of an original nitrile hydratase-producing bacterium strain obtained by knocking-out or inhibiting the amidase gene in the original strain. The construction method of the engineered bacterium is to block the expression of the amidase gene by inserting the large fragment of a recombinant suicide plasmid carrying an amidase gene fragment into a wild-type strain through the homologous recombination between the recombinant suicide plasmid and the amidase gene of the wild-type strain. Compared to the corresponding wild-type bacterium strain, both the cell growth and the nitrile hydratase expression of the engineered nitrile hydratase-producing bacterium according to the invention are increased. In the process of catalyzing the hydration of acrylonitrile to produce acrylamide, the yield of the product, acrylamide, is significantly increased, while the yield of the by-product acrylic acid is significantly decreased. The engineered nitrile hydratase-producing bacterium of the present invention has wide application prospect in the production of acrylamide by microbiological process.

The invention discloses an engineering bacteria for producing 1,3-propylene glycol and a method for constructing the same. The invention silences the phosphate transacetylase genes in a wild type strain producing 1,3-propylene glycol by utilizing a homologous recombination method and a gene insertional inactivation method so as to obtain a genetically engineered bacterium, of which the acetic acid metabolic pathway is blocked. When the 1,3-propylene glycol is fermented and produced by the engineering bacteria disclosed by the invention, the acetic acid production is largely reduced, the toxic action on cells caused by the by-product acetic acid is greatly decreased and the production rate of biomass per unit is enhanced. Moreover, the post-extracting process is simplified and the production cost is reduced as the species of the by-products are reduced. The experiments prove that the concentration of the 1,3-propylene glycol can reach more than 55g/L by fermenting the engineering bacteria provided by the invention for 28 hours according to a conventional method. The invention plays an important role in the industrial production for producing 1,3-propylene glycol by a microbiological fermentation method and has a wide application prospect.

Mutant photosynthetic microorganisms having reduced chlorophyll and increased photosynthetic efficiency are provided. The mutant strains have mutated chloroplastic SRP54 genes and exhibit increased productivity with respect to wild type strains. Also provided are mutant algal strains having mutated cytosolic SRP54 genes. Provided herein are methods of producing biomass and other products such as lipids using strains having mutations in an SRP54 gene. Also included are constructs and methods for attenuating or disrupting SRP54 genes.

The present invention relates to a gene of swine vesicular disease virus (SVDV) and the mutant strains of the gene, and the expression plasmids, the preparation process thereof. The invention also relates to a vaccine for use in the prophylaxis of swine vesicular disease composition containing the mutant strains. Furthermore, the invention provides a process for differentiating mutant strains of SVDV from the wild type strain of SVDV, coxsackievirus and foot-and-mouth disease virus by polymerase chain reaction.

The invention discloses a watermelon oxysporum pathogenic FonAGL3 gene as well as a deleted DNA fragment, a deletion mutant and application thereof, and aims to solve the technical problem of biological prevention and treatment on watermelon oxysporum. A pathogenic gene FonAGL3 derived from watermelon fusarium oxysporum is analyzed and screened by inserting watermelon oxysporum T-DNA into a mutant library, by utilizing the homologous gene replacement principle, DNA fragments of the target gene FonAGL3 are replaced by gene DNA fragments of a resistance gene hygromycin B (HPH), a FonAGL3 gene deletion mutant is obtained by establishing a gene deletion carrier and implementing genetic transformation of a wild strain FON-11-06, and the FonAGL3 mutant bacterium has a good wilt prevention and treatment effect and is environmental-friendly and low in prevention and treatment cost.

The invention relates to an endogenous bacillus subtilis positive mutant strain, a preparation method thereof, a prepared biocontrol agent and an application of the biocontrol agent in preventing and controlling pomegranate dry rot, including (1) screening of a Bacillus subtilis wild-type strain NS04 and ultraviolet mutation and breeding of a positive mutant biocontrol strain NS04307; (2) antibacterial stability of the positive mutant strain NS04307; (3) a preparation method of the positive mutant strain NS04307 biocontrol agent; and (4) application of the positive mutant strain NS04307 in preventing and controlling plant diseases. The biocontrol agent disclosed by the invention has the characteristics of wide bactericidal spectrum, good effect, difficulty in disease drug resistance generation, safety on human, livestock and crops, environmental friendliness and the like and has a better effect on the field control of the pomegranate dry rot especially. In addition, the biocontrol agent disclosed by the invention achieves outstanding inhibition activity on the growth of 15 different pathogenic bacteria, such as Sclerotiumrolfsii, Trichotheciumroseum, Exserohilumrostratum, Fusariumoxysporum, Alternariaalternate and the like.

The present invention relates to a method for rapidly detecting quinolone-resistant Salmonella spp. The invention also relates to the oligonucleotide primers and probes utilized in the method, which can differentiate mutant strains having one or two single point mutations in gyrA gene or single point mutation in parC gene from wild type strains, respectively. Said primers and probes can be effectively used for detection of nalidixic acid-resistant and/or ciprofloxacin-resistant Salmonella strains.

The present invention belongs to the field of antibiotic gene engineering, and is especially the process of cloning nicomycin biological synthetic gene sanU from one strain of Streptomyces ansochromogenes 7100 CGMCC 4.321; connecting the synthetic gene sanU with promoter of melanin biosynthetic structure gene, cloning onto the polycloning site of integrative single-copy plamid, transforming wild Streptomyces ansochromogenes 7100 CGMCC 4.321 protoplast to obtain nicomycin X component of the recombinant engineering bacterium in the yield 2 times higher than wild strain. The high-yield engineering bacterium may be used in preparing antiseptic medicines.

The invention discloses application of a guided glycosyltransferase gene, namely application of the guided glycosyltransferase gene cps2E and cps4E in improving lactobacillus plantarum extracellular polysaccharide synthesis; the cps2E and cps4E genes and a temperature-sensitive plasmid pFED760 are recombined to construct a knockout vector, the knockout vector is guided into food-borne lactobacillus plantarum competent cells, and then by means of homologous recombination, cps2E and cps4E genes are constructed to knock out strains YM 4-3-deltacps2E, YM 4-3-deltacps4E and YM 4-3-deltacps2E-4E; the capacity of the strains producing extracellular polysaccharide is determined through a phenol-sulfuric acid method, it is found that the capacity of knocking out extracellular polysaccharide produced by the strains is lower than that of wild type strains, and the double knockout strain extracellular polysaccharide yield is very low, so that the cps2E and cps4E genes play a key role in the extracellular polysaccharide synthesis, and the application has great potential in extracellular polysaccharide biosynthesis research and application fields.

In preferred embodiments, the present invention provides new isolated strains of a Geobacter species that are capable of using a carbon source that is selected from C₃ to C₁₂ organic compounds selected from pyruvate or metabolic precursors of pyruvate as an electron donor in metabolism and in subsequent energy production. In other aspects, other preferred embodiments of the present invention include methods of making such strains and methods of using such strains. In general, the wild type strain of the microorganisms has been shown to be unable to use these C₃ to C₁₂ organic compounds as electron donors in metabolic steps such as the reduction of metallic ions. The inventive strains of microorganisms are useful for improving bioremediation applications, including in situ bioremediation (including uranium bioremediation and halogenated solvent bioremediation), microbial fuel cells, power generation from small and large-scale waste facilities (e.g., biomass waste from dairy, agriculture, food processing, brewery, or vintner industries, etc.) using microbial fuel cells, and other applications of microbial fuel cells, including, but not limited to, improved electrical power supplies for environmental sensors, electronic devices, and electric vehicles.

We describe the use of chemically defined media for the fermentative production of valuable compounds on an industrial scale. Microbial strains which are suitable for fermentation on an industrial scale using a chemically defined medium include fungal, yeast and bacterial strains. Suitable strains can be obtained as wild type strains or by screening and selection after mutagenic treatment or DNA transformation.

The invention relates to an optimization method of culture conditions of alkaline pectinase gene engineering bacteria, comprising the following steps: (1) adopting a single-factor experiment to optimize the fermentation medium formation of the alkaline pectinase gene engineering bacteria to obtain a preliminarily optimized fermentation medium; (2) optimizing a target strain medium with a response surface methodology to obtain the target strain medium; and (3) optimizing the fermentation culture conditions to the target strain by a post-optimizing medium to obtain the optimization culture conditions. The invention gropes a set of optimal fermentation culture conditions to ensure that enzymatic activity produced by engineering bacteria fermentation reaches 758.7825U/ml which is improved by 50 times compared with the activity of alkaline pectinase produced by original wide strains and is improved by 3 times compared with the enzymatic activity of alkaline pectinase produced by LB fermentation medium fermentation gene engineering bacteria, so that the invention has an important meaning for improving the market competitiveness of industrial enzyme.

The present invention belongs to the field of a biological technique and relates to a RNA polymerase mutant of Bacillus spp CC09 bacterial strain of high-yield antimycotics cyclic lipopeptides substances screened by using a LB plate containing rifampin (50 mug/ml). The mutation site of the mutant is on any position of 485-490 in a RNA polymerase beta sub-unit amino acid sequence, Compared with wild type CC09 bacterial strain, the output of antimycotics cyclic lipopeptides antibiotics Iturin and Surfactin produced by the mutant can be increased by 100%-300%, the antifungal activity is increased by 20-60%, and the mutant can be used for preventing and treating a plurality of crop diseases.

The present invention relates to novel rumen bacterial mutants resulted from the disruption of a lactate dehydrogenase gene (ldhA) and a pyruvate formate-lyase gene (pfl) (which are involved in the production of lactic acid, formic acid and acetic acid) from rumen bacteria; a novel bacterial mutant (Mannheimia sp. LPK7) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl), a phosphotransacetylase gene (pta), and a acetate kinase gene (ackA); a novel bacterial mutant (Mannheimia sp. LPK4) having disruptions of a lactate dehydrogenase gene (ldhA), a pyruvate formate-lyase gene (pfl) and a phosphoenolpyruvate carboxylase gene (ppc) involved in the immobilization of CO2 in a metabolic pathway of producing succinic acid; and a method for producing succinic acid, which is characterized by the culture of the above mutants in anaerobic conditions. The inventive bacterial mutants have the property of producing succinic acid at high concentration while producing little or no organic acids, as compared to the prior wild-type strains of producing various organic acids. Thus, the inventive bacterial mutants are useful as strains for the industrial production of succinic acid.

The invention discloses a method for improving ethanol tolerance of synechocystis PCC6803 and an application, and belongs to the field of industrial microorganism. With the application of the method, a synechocystis PCC6803 strain with ethanol tolerance obviously improved is obtained, and the strain is applicable to the construction of genetically engineered bacteria for producing fuel ethanol. According to the method provided by the invention, an sll0687 gene in the synechocystis PCC6803 is knocked out through homologous recombination; and the ethanol tolerance of the synechocystis PCC6803 strain IK2 obtained through the application of the method is significantly improved. Under 1.5% (v/v) ethanol stress, the growth state of the strain is obviously better than that of a wild-type strain. The ethanol-tolerance strain prepared by the invention has important theoretical and practical significance for the construction of the genetically engineered bacteria for producing the fuel ethanol; and the strain has a broad application prospect.

The invention discloses extreme halophilic archaea engineering bacteria for producing bioplastics PHBV (Poly-(HydroxyButyrate-co-Hydroxy Valerate)) by effectively utilizing a carbon source. The recombined extreme halophilic archaea is extracellular polysaccharide synthesis function-deficient engineering bacteria obtained by deleting at least one protein function expressed by an extracellular polysaccharide synthesis cluster in the genome of the extreme halophilic archaea Haloferax mediterranei. The extreme halophilic archaea has the advantages that infectious microbe is not easy to pollute, PHA (Poly Hydroxy Alkanoate) is convenient to extract, the PHBV from a non-correlated carbon source can be synthesized, and the like, and is considered as a highly preponderant PHBV producing strain. The extracellular polysaccharide synthesis function-deficient strain engineering bacteria are characterized in that the polyhydroxyalkanoate can be produced from various carbon sources such as glucose, starch and whey more efficiently in contrast with a wild type strain, the concentration of the PHBV is 20% higher than that of the wild type strain under the same fermentation conditions, and the problems such as sticking, lots of bubbles and dissolved oxygen reduction of a culture solution caused by extracellular polysaccharide accumulation are also solved.