FIELD: biotechnology, microbiology, antibiotics, genetic engineering, molecular biology.
SUBSTANCE: invention relates to a polynucleotide comprising nucleotide sequences encoding product of gene aveC molecules of that can be used for changing the ratio of amount of avermectins of class 2:1 produced in fermentation cultures of S. avermitilis. This nucleotide sequence is similar essentially with aveC allele sequence from S. avermitilis, plasmid pSE186 (ATCC 209604) sequence encoding product of gene aceC from S. avermitilis, nucleotide sequence of aveC open reading frame but this nucleotide sequence comprises mutations encoding combination of amino acids owing to the strain S. avermitilis ATCC 53692 in cells of them allele aveC of wild type is inactivated is able to produce avermectins of class 2:1 in the ratio 0.35:1 or less (when avermectins represent cyclohexyl B2 and cyclohexyl B1, respectively). Also, invention relates to vectors, host-cells and mutant strains of S. avermitilis wherein aveC gene is inactivated or mutated with the possibility for changing the ratio of amount of avermectins of class 2:1. Also, invention relates to a method for preparing the mutated strain (combination of amino acid changes are given in the invention claim) and a method for preparing avermectins of class 2:1 in the reduced state and to a composition prepared by a method given above. Using the proposed invention provides preparing the avermectins composition of class 2:1 with the reduced amount of avermectin B2 in the mixture. Invention can be used in producing avermectin antibiotics.
EFFECT: improved preparing method of avermectins.
17 cl, 21 dwg, 4 tbl, 8 ex
