The Study Of Relationships Between PilA1and Suspension Ability In S. Elongatus PCC7942

Nowadays, cyanobacteria blooms have been occurring in lakes worldwide and have been reported to have harmful effects on human being. In fresh water, the environmental problem of cyanobacteria blooms are the consequence of an excess of nutrients we commonly call eutrophication. One of the main reasons of blue-green algae bloom is that they can occupy the most appropriate ecological surface. Studying "vertical motility" of cyanobacteria plays a key role in understanding the mechanism of blue-green algae bloom.Both Synechococcus sp. PCC7942and Anabaena sp. PCC7120are model organisms. We obtained six pilus mutation strains from Susan Golden’s lab and found they show different decrease in suspension ability, the most significant strain is26D12. we found that Synechococcus sp of ApilAl show poor suspension capability compare with the wild strain.we clone the pilAl gene and introduce the exogenous gene into26D12and Anabaena sp. PCC7120by the conjugal transfer system, then to observe whether their suspension capability has altered or not, which is of great significance to the molecular genetic mechanism study of Synechococcus sp. PCC7942and Anabaena sp. PCC7120. The main research results were as follows:(1) We clone the pi1A1gene and construct pET-28a-pilAl plasmid.PILA1protein is induced and expressed in E.coli, but no active protein are achieved.(2) We clone the pilAl gene and introduce it into26D12and Anabaena sp. PCC7120through conjugal transfer system, and we successfully acquired the mutation strains. Through suspension experiment,26D12with pi1A1gene restore the suspension ability, and the cell sendimentation rate of Anabaena, which has a poor suspension ability, is also greatly reduced, inditating that PILA1plays a important role in the algae’ suspension ability. TEM pictures also show that26D12has a significantly different cells compared with26D12-pilAl. (3) We introduce the plasmid pEGFP-PBS into Synechococcus sp. PCC7942,26D12and26D12-pilAl by natural transformation.then using the FACS to identify the transformation efficiency of them. Wild type and26D12-pilAl could be transformed and express GFP, but26D12could not. Consequently, we concede that the pilus play a key role in the transformation.