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Improvement of clavulanic acid production in Streptomyces clavuligerus F613-1 by using a claR-neo reporter strategy
Qin, Ronghuo; Zhong, Chuanqing; Zong, Gongli; Fu, Jiafang; Pang, Xiuhua & Cao, Guangxiang
Abstract
Background: Streptomyces clavuligerus was the producer of clavulanic acid, claR, a pathway-specific
transcriptional regulator in S. clavuligerus, positively regulates clavulanic acid biosynthesis. In this study, the
promoter-less kanamycin resistance gene neo was fused with claR to obtain strain NEO from S. clavuligerus
F613-1. The claR-neo fusion strain NEO was mutated using physical and chemical mutagens and then screened
under high concentrations of kanamycin for high-yield producers of clavulanic acid.
Results: The reporter gene neo was fused downstreamof claR and used as an indicator for expression levels of claR
in strain NEO. After three rounds of continuous treatment and screening, the high-yield clavulanic
acid-producing strain M3-19 was obtained. In the shaking flask model, the clavulanic acid titer of M3-19
reached 4.33 g/L, which is an increase of 33% over the titer of 3.26 g/L for the starting strains S. clavuligerus
F613-1 and NEO.
Conclusions: Our results indicate that neo can be effectively used as a reporter for the expression of late-stage
biosynthetic genes when screening for high-yield strains and that this approach has strong potential for
improving Streptomyces strains of industrial value.
Keywords
claR; Clavulanic acid biosynthesis; Co-transcription; Fermentation; Fusion; Kanamycin; Mutagenesis; Mutagens; Promoter-less; Reporter gene; Transcriptional regulator
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