Cloning and expression analysis of geosmin synthase gene from Aphanizomenon gracile北大核心CSCD

Geosmin is a secondary metabolite responsible for earthy odors. The occurrence of geosmin has great impact on the quality of water environment. The gene essential for geosmin biosynthesis have been identified in several species. But little is known about the mechanism of geosmin synthesis in Aphanizomenon gracile. This study attempted to clone the gene involved in geosmin biosynthesis of Aphanizomenon gracile a nd a nalyze t he geosmin production u nder d ifferent e nvironments. T he high-efficiency thermal asymmetric interlaced PCR (hiTAIL-PCR) was used to amplify the full-length of geosmin synthase gene from Aphanizomenon gracile (WH-1). Real time PCR (RT-PCR) was applied to quantify the geosmin production in different light and temperature. As a result, geo, a geosmin synthase gene from Aphanizomenon gracile (WH-1) was cloned by hiTAIL-PCR. The full-length open reading frame (ORF) of geo was 2 262 bp, coding for a protein of 753 amino acids. Meanwhile, WH-1 was treated with different environment conditions and mRNA expression levels of geo were quantified by RT-PCR. It was found that low temperature (15 °C), high light intensity (35 μmol m-2 s-1) and continuous light illumination were beneficial to the expression of geo. The successful amplification of geosmin synthase gene verified that hiTAIL-PCR is an effective and simple procedure of low cost. The result provides fundamental knowledge on the monitoring and prevention for odorants.