Streptomyces HS7522 Strain for Milbemycin A4 Fermentation
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Solution Overview
Problem
Current methods for producing milbemycin A4 face challenges in achieving high yields and separating it from milbemycin A3 due to their similar proportions in fermentation broths, leading to difficulties in application and increased production costs.
Innovation Solution
Development of a new microbial strain, Streptomyces HS7522, which significantly increases the yield of milbemycin A4 to over 4000 ug/ml, accounting for more than 80% of the total A3 and A4 content, through optimized fermentation conditions and mutagenesis, allowing for high-unit fermentation with reduced impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional fermentation methods are used to produce milbemycin, then both milbemycin A3 and A4 are produced in similar proportions (about 1:2), but this makes it difficult to separate A3 and A4 single components and reduces final yield
Solution Approach 1:
The patent applies parameter changes by modifying the fermentation conditions and using a specifically selected Streptomyces strain (Streptomyces bingchengensis) that naturally produces milbemycin A4 in higher proportions (A3:A4 ratio improved from 1:2 to approximately 1:3 or better). This changes the compositional parameters of the fermentation broth to favor A4 production, thereby improving both yield and separability without requiring complex separation processes
Solution Approach 2:
Instead of attempting to separate A3 and A4 from a mixed fermentation broth (the conventional approach), the patent inverts the strategy by selecting a strain and optimizing conditions that naturally produce predominantly A4. This reversal of the production-separation sequence eliminates the need for difficult separation operations and directly achieves high-purity A4 in high yield
2Productivity
If mutagenesis and fermentation optimization are applied to increase milbemycin production, then unit content increases (from 150 mg/L to over 2000 mg/L), but the ratio of A3 to A4 remains similar (about 1:2), still requiring separation
Solution Approach 1:
The patent changes the compositional parameter of the fermentation broth by using Streptomyces bingchengensis, which naturally produces milbemycin with an A3:A4 ratio of approximately 1:3 or better (compared to the conventional 1:2 ratio). This parameter change in the product composition makes separation easier while maintaining high productivity
Solution Approach 2:
The patent uses homology-based cloning to copy and express the milbemycin biosynthesis gene cluster from Streptomyces bingchengensis into a heterologous host system. This copying of the genetic blueprint allows reproduction of the favorable A4-enriched production phenotype in a controlled manner, achieving both high yield and improved separability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The strain improves the proportion of milbemycin A4 in fermentation products, reducing production costs and expanding its application range, with a titer increase compared to original strains, facilitating industrial production.
Implementation Method 1
a method for producing milbemycin A4 by the fermentation culture of the streptomyces
Data Source
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AI summary
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 September 16, 2014.