Abstract: Some researchers have the opinion that cyanobacteria can form vacuoles owing to lack of nutrition or senescence.There were vacuoles in the old cells while the micrographic structure of cyanobacteria was studied.Whether there are vacuoles in the cyanobacteria is still in the air.The recent study shows that some inorganic salts can induce the formation of vacuoles in cyanobacteria and this kind of vacuole has been isolated successfully.The further study shows inorganic salts can induce vacuoles and spheroplasts in the unvacuolized normal cells of cyanobacteria simultaneously.This kind of vacuole also can be isolated easily.why the unvacuolized normal cells of cyanobacteria can form the vacuolized spheroplasts?It is a new problem worthwhile to study.This research chooses Anabaena sp.595 to treat in the presence of several different combinations of some inorganic salts with 0.1%(w/v)mixed with lysozyme,and a preliminary study on the inducing conditions of vacuolized spheroplasts in cyanobacteria has been done.Anabaena sp.595 was treated in the presence of 0.15ml/l KNO3、KCl、K2SO4、KH2PO4、K2HPO4、NaNO3、NaCl、Na2SO4、NaH2PO4、Na2HPO4、(NH4)2SO4、MgSO4 and CaCL2 mixed with 0.1%(w/v)lysozyme for 4 hours.The results show that protoplasts rather than vacuolized spheroplasts could be easily induced by KH2PO4、K2SO4、Na2SO4、NaH2PO4、 (NH4)2SO4、MgSO4 and CaCl 2.On the contrary,rich vacuolized spheroplasts were induced by KNO3、NaNO3 and NaCl.The inducing effects were not evident under the treatment of two salts of similar concentration like KNO3 and NaCl、KNO3 and (NH4)2SO4、NaCl and(NH4)2SO4 mixed with 0.1%(w/v)lysozyme.However,the inducing rate of both the spheroplasts and vacuolized spheroplasts markedly increased by three salts of similar concentration like NaCl、KNO3 and (NH4)2SO4 with 0.1%(w/v)mixed with lysozyme;similar results were obtained under the treatment of five salts of NaCl、KNO3、(NH4)2SO4、Na2HPO4 and KH2PO4 mixed with lysozyme.On these conditions,the percentage of vacuolized spheroplasts reached 66.90%～79.97%.The results mentioned above indicate that some kinds of inorganic salt have the effects of inducing the spheroplasts to form vacuoles.But because the effects are very weak,it is difficult to apply single inorganic salt to induce the spheroplasts to form vacuoles in practice.The results also show that synergistic effects of several kinds of inorganic salt are necessary to induce the spheroplasts to form vacuoles.The preparation of high frequency spheroplasts makes for the high yield of vacuoles.However,this study can not answer whether there are some differences between the vacuoles in the vacuolized spheroplasts and that in the normal cells of cyanobacteria.The further study on this question will be useful.