蓝藻聚球藻高二氧化碳需求突变株的研究

ISOLATION AND ANALYSIS OF A HIGH CO_2 REQUIRING MUTANT OF CYANOBACTERIUM SYNECHOCOCCUS PCC7942

利用化学诱变法获得了蓝藻聚球藻10％CO2生长需求的突变株N150。突变株N150具较高的无机碳运输速率和无机碳库，表观光合作用对外源无机碳的亲和性与已知的其它高二氧化碳需求突变株有显著区别。突变株N150的突变缺陷主要在不能适应低CO2条件。当有Na+（100mmol／L）存在时，突变株可恢复在较低CO2浓度（1％）下生长的能力。

Some physiological charactenshcs of a mutant（No． 150） of SynechococcusPCC7942， which reqruires very high CO2（10%） for growth， were studied． The mutantwas isolated after ethylmethyl sulphonate（EMS） mutagenesls and ampicillin enrichment Unlike other cyanobacterial high CO2 requiring mutant,where the apparent photosynthetice affinity for inorganic carbon is approximately 2 oders of magnitude lower than that of the wild type， the mutant exhibits photosynthetic chaxactensticssimilar to those of its wild type grown at high CO2（Fig 2）．Furthermore ,the Ciinflux and efflux rate ,and Ci pool of the mutant are two and three times tigher thanthat of the wild type grown at high CO2， respectively（Table 1）． It was later foundthat with added NaCl at a concentration no less than 100mmol／ L， the mutant couldgrow equally Well in air containing 1％ CO2 as that in air containing 10％ CO2． It issuggested that Sodium could partly alleviate the demanding of the mutant for veryhigh CO2 The results indicated thgt mutant Is msnly defeCted in the ability to adapt to low CO2 conditions．