Cyanobacterial blooms have attracted worldwide attention while the eutrophication problems of freshwater bodies have been worsening. Recent researches have been focused on Microcystis blooms but there is only few research on water blooms caused by another kind of cyanobacteria, Cylindrospermopsis in China. However, many reports about Cylindrospermopsis blooms and cylindrospermopsin (CYN) produced by Cylindrospermopsis have been published by foreign scientists.  

CYN is a zwitterionic alkaloid, which can cause injury and cell necrosis on multiple organs, including the liver, thymus, kidneys, and heart. Besides Cylindrospermopsis, some species of other cyanobacteria such as Raphidiopsis, Aphanizomenon, Anabaena and Oscillatoria can also produce CYN. Extracellular accumulation and poor decomposition of CYN were found in lake water, which indicate a potential risk for human health.  

The Research Group of Biology of Harmful Algae (Principal Investigator: Prof. LI Renhui) at Institute of hydrobiology, Chinese Academy of Sciences (IHB) recently made new progress in the molecular basis for biosynthesis of CYN. Raphidiopsis is phylogenetically close to Cylindrospermopsis, and the two genera usually co-occur in freshwater bodies. IHB researchers isolated a Raphidiopsis strain from Chidonghu Lake (China) and detected deoxy-CYN in the cyanobacterial cells.  

The CYN biosynthesis gene cluster of this strain was sequenced. The cyrI gene showed a 92 bp sequence insertion and this insertion mutation causes a frame-shift and several stop codons within thecyrI gene. The CYN biosynthesis was thought to be interrupted at the stage of deoxy-CYN because of this mutation and the result confirms the predicted function of CyrI in CYN biosynthesis. This research makes a contribution to understanding the biosynthesis mechanism of CYN, evolution of biosynthesis genes and phylogenetic relations of Cylindrospermopsis and Raphidiopsis. The research also lays a foundation for the molecular detection, monitoring and early warning of CYN. 

The results have been published in Applied and Environmental Microbiology, April 2012 vol. 78 (7):2256-2263. 

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http://aem.asm.org/content/78/7/2256.full.pdf+html