89 results about "Streptomyces avermitilis" patented technology

The invention discloses a streptomycete constitutive promoter and applications thereof, and provides an DNA fragment. The DNA fragment is any one selected from the following DNA molecules in 1)-3): 1) an DNA molecule represented by the sequence 1 in a sequence table; 2) an DNA molecule with promoter functions and hybrid with the DNA molecule shown in 1) under strict conditions; 3) an DNA molecule with more than 90% of homology with the DNA molecule shown in 1) and with promoter functions. The experiments shows that a strong constitutive promoter kasO*p is screened out, and the promoter and the erythromycin promoter ermE*p are compared in representation of transcriptional level and expression level in streptomyces coelicolor, streptomyces avermitilis and streptomyces venezuelae, and the results show that the modified promoter kasO*p is better than the the erythromycin promoter ermE*p.

The invention provides a genetic engineering bacterium capable of improving the yield of abamectin, which is a recombinant bacterium over-expressed by ribosome circular factors obtained by the introduction of frr genes of the encoded ribosome circular factors in acitretin streptomycete into the acitretin streptomycete through an expression vector. The genetic engineering bacterium can be directly used for fermentation production of the abamectin and for improving the fermentation unit of the abamectin and reducing the production cost.

The invention belongs to the technical field of microorganisms, and particularly relates to a method for preparing avermectin (Avermectins). The method comprises the following steps: cultivating a streptomyces avermitilis strain capable of generating avermectin and genetic improved bacteria thereof in a first stage of fluid nutrient medium, and then inoculating into a second stage of fluid nutrient medium as a seed solution; fermenting and cultivating after inoculating the seed solution into the second stage of fluid nutrient medium, and feeding a sodium propionate precursor to carry out feeding cultivation; collecting the avermectin B1a from fermentation broth after fermentation is finished. The effective method has the characteristics of being high in production efficiency and the like.

A process for preparing abamectin (AVM) by use of the bacterium with high AVM secreting power includes such steps as mutagenizing the initial streptomyces avermitilis (CCTCC No.M200028), choosing the bacteria (CCTCC No.M204069 and CCTCC No.M204070) with high potency and high secretion rate, fermenting to obtain wax ball suspension of AVM, and extracting AVM by five-step method.

The invention discloses a method for producing enramycin by fermentation. Cabicidin streptomyces avermitilis is used as a fermentation strain in the method; and water is supplied to the fermentation solution in the fermentation process of constant temperature culture in a fermentation medium, so that the dissolved oxygen quantity of the fermentation solution is improved, and the fermentation level of the enramycin is improved. The method is simple and feasible; and after a proper amount of water is supplied at proper time in the fermentation culture process, the fermentation level of the enramycin can be improved by about 130 percent.

The invention relates to a construction method for streptomycete expression plasmids and a production method for keratinase. The construction method for streptomycete expression plasmids includes the following steps: a promoter Xi of actinoplanes missouriensis xylose isomerase and a terminator of streptomycete avermitilis amylase are sleeved, and the promoter-shine-dalgarno (SD) sequence comes from 90 to 269bp of an actinoplanes missouriensis xylose isomerase gene; a cloned src family kinases (sfks) gene is inserted in a construction expression frame structure of a synthetic Xi promoter-SD-amyA2 terminator fragment, and then a conventional method is used for constructing the streptomycete expression plasmids. The production method for keratinase includes: leading the streptomycete expression plasmids into an expression host of streptomycete lividans TK24 through conjugal transfer, performing recombinant expression and generating the keratinase. Specific activity of a crude enzyme solution is 1700 U/mg after expression of the expression plasmids in the streptomycete lividans TK24 and is improved by 50 times compared with specific activity of starting strain streptomycete fradiae varieties S-221, and yield of the keratinase is much higher than starting strains after the expression.

The invention discloses a method for screening a methionine resistant deinsectization streptomyces avermitilis strain, which belongs to the field of the screening of microbial strains. The method comprises the following steps of: performing ultraviolet mutagenesis on deinsectization streptomyces avermitilis spore suspension; performing enrichment on tolerant strains by using a methionine-containing liquid culture medium; screening methionine solid-plate tolerant strains; and screening strains of which the shake flask capacity is improved compared with that of parent strains through preliminary screening, secondary screening and genetic stability research so as to provide a feasible method for screening the deinsectization streptomyces avermitilis strain. The shake flask production capacity of the deinsectization streptomyces avermitilis strain screened by the method is greatly improved, and the genetic stability is high.

The invention belongs to the technical field of microbial fermentation, and particularly relates to a method for producing avermectins by fed-batch fermentation by using an air-lift loop reactor. Themethod comprises the following steps that streptomyces avermitilis is inoculated to a slant culture medium for culture, and a spore slant is taken to prepare into a spore suspension; the spore suspension is inoculated to a seed culture medium and cultured to a logarithmic growth phase; and the streptomyces avermitilis spore suspension cultured to the logarithmic growth phase is transplanted into the air-lift loop reactor provided with a fermentation culture medium for fermentation culture, and a supplementary medium is added in batches in the middle and later periods of fermentation. The method adopts the air-lift loop reactor as a fermentation vessel, optimizes the fed-batch process and the composition of the supplementary medium, effectively reduces the bacterial infection rate in the fermentation culture process, and significantly increases the titer of the avermectins in fermentation liquid.

The invention provides a method for improving the yield of avermectins and a producing strain thereof. A deletion vector of a sig6 gene, which is used for encoding an extracytoplasmic function (ECF) subfamily ribonucleic acid (RNA) polymerase sigma factor, in Streptomyces avermitilis is introduced into the Streptomyces avermitilis to obtain a recombinant strain in which the sig6 gene is lacked toensure that the recombinant strain cannot synthesize sig6 any more, so that the yield of the avermectins is improved. The genetic engineering strain can be directly used for fermentation production of the avermectins, improves the fermentation unit of the avermectins, and reduces production cost.

The invention discloses an efficient screening method for an abamectin high-producing strain and belongs to the technical field of metabolic engineering. The method includes the steps that firstly, several different abamectin inclined mediums are compared, a proper inclined medium is selected for abamectin, and goodness of an original strain is guaranteed. ARTP mutation and other similar mutation treatment means are carried out on the original strain abamectin, a porous plate culture method and a microplate reader high-throughput test method are combined for use, the whole screening process is simplified, and screening efficiency is improved. A microplate reader preliminary screening method is verified, the pore plate OD value measured by a microplate reader and a pore plate tier obtained after efficient liquid detection are compared, it is found that good relevance is achieved, and therefore the preliminary screening feasibility and accuracy of the microplate reader are proved. The high-producing mutant strain of abamectin is screened out, and compared with original bacteria, the yield of abamectin of the mutant strain is increased by 10% or above on a shake flask and increased by 10% or above on a 30L fermentation tank.

The invention discloses a high-producing strain containing abamectin, and also provides a screening method of the high-producing strain containing abamectin. The high-producing strain containing abamectin is (Streptomyces avermitilis) AV-185S, the preservation unit of the high-producing strain is the China general microbiological culture collection center, the preservation date of the high-producing strain is March 15, 2016. The screening method mainly comprises the steps of a, preparing a spore suspension; b, conducting ultraviolet-lithium chloride compound mutation treatment; c, preparing a streptomyces avermitilis liquid medium; d, screening the high-producing strain through liquid culture in a deep well plate; and e, detecting the strain fermentation potency. The average fermentation potency of the (Streptomyces avermitilis) AV-185S screened according to the screening method can be up to 6842.8 ug/mL.

The invention discloses a method for screening abamectin high-yield strain in high throughput based on a flow cytometry, belonging to the technical field of high-troughput screening. The method comprises the following steps: performing PI dyeing method on mutated spores with different activities, correctly distinguishing a spore area with activity by regulating and optimizing various parameters such as FSC, SSC and voltage threshold, and excluding the interference mixed with the background in flow cytometry detection due to oversmall volume of spores. The screened live spores are subjected to a solid-liquid combined high-throughput culturing scheme to effectively improve the growth rate of an abamectinpore plate. According to the invention, the abamectin with activity can be screened based on the flow cytometry, and a novel and effective manner is provided for the high-throughput screening of abamectin.

An optimized production method of abamectin belongs to the technical field of biomedicine, and includes of constructing over-expression plasmid pFAveT containing gene sav933 and gene sav934, transferring the expression plasmid into streptomyces avermitilis 3-115, and finally realizing yield increase. The yield of specific antibiotics is increased by means of over expression of efflux gene in strains for industrial production of antibiotics.