A method for improving the production of Streptomyces polyketide compounds is provided. The method greatly improves the capability of the Streptomyces polyketide compounds by strengthening a triacylglycerol decomposition pathway in Streptomyces during the stationary phase. A method for switching the primary metabolism of Streptomyces to the secondary metabolism, Streptomyces producing polyketide compounds, and use thereof are also provided.

Provided are a Streptomyces (Streptomyces hygroscopicus) HS7522 and a method for preparing milbemycin A4 by culturing the Streptomyces. The Streptomyces (Streptomyces hygroscopicus) HS7522 of the present invention is deposited in China General Microbiological Culture Collection Center with an accession number of CGMCC No. 9671 on Sep. 16, 2014.

The present disclosure provides proteins, nucleic acids, vectors, and host molecules useful for the production of compounds of interest, and methods for their use.

Provided are a Streptomyces (Streptomyces hygroscopicus) HS7522 and a method for preparing milbemycin A4 by culturing the Streptomyces. The Streptomyces (Streptomyces hygroscopicus) HS7522 of the present invention is deposited in China General Microbiological Culture Collection Center with an accession number of CGMCC No. 9671 on Sep. 16, 2014.

Provided are a Streptomyces (Streptomyces hygroscopicus) HS7523 and a method for preparing milbemycin A3 by culturing the Streptomyces. The Streptomyces (Streptomyces hygroscopicus) HS7523 is deposited in China General Microbiological Culture Collection Center with an accession number of CGMCC No. 9672 on Sep. 16, 2014.

A strain for high-yield production of milbemycin and use thereof is disclosed. In the present invention, an original strain MI-W1-2017001 is subjected to mutation breeding by an atmospheric and room temperature plasma mutation method to obtain a high-yield strain HZMRYB-5. The fermentation level of the strain is improved by about 70% compared with the original strain, and the fermentation level is further improved by about 35% through optimization of a fermentation process and a formulation, so that the fermentation cost of the product is further reduced, and requirements for the industrial fermentation level are met. On the basis of optimizing the fermentation process, the ratio of A3 and A4 in a fermentation liquid is nearly 3:7 through mixed fermentation of the strain MI-W1-2017001 and the strain HZMRYB-5, so that market demands are greatly met, the process steps of separation, purification and then mixing are reduced.

A strain for high-yield production of milbemycin and use thereof is disclosed. In the present invention, an original strain MI-W1-2017001 is subjected to mutation breeding by an atmospheric and room temperature plasma mutation method to obtain a high-yield strain HZMRYB-5. The fermentation level of the strain is improved by about 70% compared with the original strain, and the fermentation level is further improved by about 35% through optimization of a fermentation process and a formulation, so that the fermentation cost of the product is further reduced, and requirements for the industrial fermentation level are met. On the basis of optimizing the fermentation process, the ratio of A3 and A4 in a fermentation liquid is nearly 3:7 through mixed fermentation of the strain MI-W1-2017001 and the strain HZMRYB-5, so that market demands are greatly met, the process steps of separation, purification and then mixing are reduced.