Zatiovskaia T V, Kosenko L V, Iurgel' S N, Simarov B V
Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv.
Mikrobiol Z. 2000 Mar-Apr;62(2):27-37.
Four Tn5-transposon LPS mutants of Sinorhizobium meliloti (Tb9, Tb29, Ts22 and Ts32) have been studied. Each of four mutants has been established to contain a single insertion of Tn5-transposon in its genome. All mutations are located on a chromosome. Nodulation competitiveness (NC) of mutants towards the parent strain of S. meliloti CXM1-188 was investigated by resistant method using coinoculation of mutant and parent strain in the ratio 1:1. It was shown that NC was only 19-31% and 8-10%, for two strains Tb29 and Ts22, respectively which had lost the capability to synthesize higher molecular weight form of lipopolysaccharide (LPS1). Nodulation competitiveness of two other strains (Tb9 and Ts32) which retained the capability to synthesize LPS1 although in modified form varied from 49 to 62% and did not differ from NC of strain CXM1-188. The investigation of nodule formation rate has shown that four LPS-mutants did not differ from the parent strain by the number of root nodules. However the appearance of nodules induced by the mutant Tb29 was registered 7 days later than the nodules formed by other LPS-mutants and CXM1-188 strain. Obtained data concerning a single Tn5-insertion in genome of each of four S. meliloti LPS-mutants testify to the fact that both the disturbance of lipopolysaccharide synthesis and change of nodulation competitiveness in mutants Tb29 and Ts22 are results of a single mutation.
对苜蓿中华根瘤菌的4个Tn5转座子脂多糖突变体（Tb9、Tb29、Ts22和Ts32）进行了研究。已确定这4个突变体中的每一个在其基因组中都含有单个Tn5转座子插入。所有突变都位于染色体上。通过抗性方法，以1:1的比例共接种突变体和亲本菌株苜蓿中华根瘤菌CXM1-188，研究了突变体对亲本菌株的结瘤竞争力（NC）。结果表明，对于失去合成高分子量形式脂多糖（LPS1）能力的两个菌株Tb29和Ts22，其NC分别仅为19%-31%和8%-10%。另外两个菌株（Tb9和Ts32）虽然能够合成修饰形式的LPS1，但其结瘤竞争力在49%至62%之间变化，与菌株CXM1-188的NC没有差异。根瘤形成率的研究表明，4个脂多糖突变体在根瘤数量上与亲本菌株没有差异。然而，由突变体Tb29诱导形成的根瘤比其他脂多糖突变体和CXM1-188菌株形成的根瘤晚7天出现。关于苜蓿中华根瘤菌4个脂多糖突变体中每一个在基因组中单个Tn5插入的所得数据证明，突变体Tb29和Ts22中脂多糖合成的干扰和结瘤竞争力的变化都是单一突变的结果。
