过表达GDP-D-甘露糖焦磷酸化酶(GMP)基因提高灵芝多糖的生产

灵芝多糖是灵芝的主要生物活性成分之一,具有多种药理活性,但灵芝多糖的低产量限制了其广泛应用.相关研究表明,灵芝中过表达多糖生物合成相关基因能够提高多糖产量,但过表达GDP-D-甘露糖焦磷酸化酶(GMP)基因提高灵芝多糖产量未有报道.本研究克隆获得了灵芝gmp基因,并成功构建出了过表达gmp基因的工程菌株(GMP菌株),...

Overexpression of GDP-D-mannose pyrophosphorylase(GMP) gene improves the production of polysaccharides in Ganoderma lingzhi

Polysaccharide is one of the main bioactive components of Ganoderma lingzhi and exhibits multiple pharmacological activities, however, the low production titer of polysaccharide greatly limits its wide application. Research has shown that overexpression of polysaccharide biosynthetic related genes results in increase of polysaccharide production in Ganoderma lingzhi, yet no study reports the enhancement of polysaccharide production through overexpression of the GDP-D-mannose pyrophosphorylase (GMP) gene. In this study, the gmp gene was cloned and the gmp gene over-expression strain (GMP strain) was successfully constructed, and further, intracellular polysaccharide (IPS) and extracellular polysaccharide (EPS) production and the expression of phosphomannomutase 1 (PMM1) gene and phosphomannomutase 2 (PMM2) gene related to GDP-mannose synthesis of wild-type strain (WT) and GMP engineered strain were analyzed. Results showed that the overexpression of gmp gene increased the accumulation of polysaccharide in Ganoderma lingzhi submerged culture. The highest content of EPS and IPS of the GMP overexpression strain reached 0.991g/L and 21.59mg/100mg dry weight, and was 21.1% and 19.5% higher than those of the WT strain. Moreover, the results showed that the overexpression of gmp gene in Ganoderma lingzhi also improved expression of pmm1 and pmm2 genes. Compared with the WT strain, the expression levels of pmm1 and pmm2 genes in the GMP strain were up-regulated by 2.87 times and 2.55 times, respectively. This study demonstrated that overexpression of gmp gene was an effective method to increase the production of Ganoderma lingzhi polysaccharides. The increase of gmp gene expression improved the synthesis of Ganoderma lingzhi polysaccharide and the expression of pmm1 and pmm2 genes.