苜蓿根瘤菌聚羟丁酸代谢突变体的竞争生长和结瘤能力以及外源生物素的影响  

Growth and Nodulation Competitiveness of Poly-3-hydroxybutyrate Metabolism Mutants of Sinorhizobium meliloti and the Effects of Exogenous Biotin

作　　者：戴美学[1] 武波[2] 柏学亮[2] 张成刚[3] 马庆生[2] 

机构地区：[1]山东师范大学生命科学学院,济南250014 [2]广西大学农业分子遗传农业部重点实验室,南宁530005 [3]中国科学院沈阳应用生态研究所,沈阳110015

出　　处：《农业生物技术学报》2003年第6期633-637,共5页Journal of Agricultural Biotechnology

摘　　要：对苜蓿根瘤菌(Sinorhizobium meliloti)聚羟丁酸(PHB)代谢突变体与野生型菌株之间,以及不同突变体之间的竞争生长和竞争结瘤能力在不同培养条件下进行了测定,并研究了外源生物素对各突变体竞争生长和竞争结瘤能力的影响。结果表明:①PAbC 突变体菌株与野生型菌株共培养,不论培养基中添加、不添加外源生物素,pAbC 突变体均表现出生长竞争能力的严重缺陷;竞争结瘤实验也显示,该突变体同野生型菌株竞争结瘤能力大幅下降;说明 PHB 合成能力的缺陷影响了菌株的竞争生长和竞争结瘤能力。②bdhA 突变体与野生型菌株共培养,在不添加外源生物素的情况下,bdhA 突变体同野生菌株竞争生长的能力有明显缺陷,但在添加外源生物素的情况下,其竞争生长能力有明显提高;bdhA::Tn5突变体与 phbC::Tn5-233突变体共培养,如培养基中不添加外源生物素,二者间的竞争生长能力无大的差异;但若添加外源生物素,则 bdhA 突变体的竞争生长能力明显高于 phbC 突变体;表明外源生物素对 bdhA 突变体的竞争生长能力有重要作用。The growth and nodulation competitiveness ofpoly-3-hydroxybutyrate(PHB)metabolism mutants of Sinorhizobium meliloti against wild-type strain and other mutants were investigated under different culturing conditions and the effects of exogenous biotin on the competition abilities of PHB mutants were studied.The effect of cycling and continuous cycles in the presence and absence of exogenous biotin resulted in the bdhA and the phbC mutants being out-numbered by the wild type.Both mutants at the end of the experiments represented only about 30% of the population.These results suggested phbCand bdhA genes play an important role during survival of S.meliloti.The phbCmutant was severely deficient in growth competiton both in the presence and absence of exogenous biotin.The bdhA::Tn5 mutant performed similarly to the phbC mutant under biotin limited conditions and was less defective in growth in the presence of external biotin.The bdhA deletion mutant in fact out competed the wild type of S.meliloti.All of the mutants were equally competitive with the wild type when the competition assay was performed in TY medium.Growth competition of bdhA::Tn5 and phbC::Tn5-233 mutants with each other did not show any differences when subjected to fluctuating carbon availability or carbon starvation in the absence of biotin.However,when these mutants competed in the presence of biotin,the bdhA::Tn5 mutant performed better than the phbC::Tn5-233 mutant did.When the bdhA and phbC mutants were subjected to repetitive rounds of cycling through carbon-rich media alone,absence of biotin did not affect bdhA mutant competition ability. Co-inoculation of the bdhA or phbC mutants with the wild type resulted in clear predominance of nodules being occupied by the wild type,but the bdhA deletion mutant was much more competitive than the wild type strain.When bdhA and phbCwere co-inoculated together,the inability to degrade PHB(bdhA mutant)showed more severe effect on nodulation ability than the inability to accumulate PHB(phbCmutant).

关 键 词：苜蓿根瘤菌 聚羟丁酸 突变体 生物素 

分 类 号：Q939.114[生物学—微生物学]