无机磷溶解菌RW8的筛选、鉴定及对白三叶促生效果研究

从白三叶根际分离筛选9株溶磷微生物,并对挑选菌株进行形态、细胞以及种属鉴定,并分析其对白三叶的促生效果。通过分析溶磷圈与溶磷菌落直径的大小与比值获得溶磷量与持续溶磷能力较强的RW8菌株。通过形态与扫描电镜观察发现RW8是具有鞭毛的短杆菌,其菌落形态表面光滑,不透明;将RW8 16S rDNA序列比对NCBI数据库发现其与阴沟肠杆菌属(Enterobacter sp.)的同源性高达99.5%,Biolog鉴定其与阴沟肠杆菌(Enterobacter cloacae ss dissolvens)的相似性为0.610。RW8溶磷量达424.85 μg/mL,溶磷能力可能与RW8的产酸性能(12.30 μg/mL)密切相关。RW8对白三叶根系与幼苗的生物产量的分配有显著影响,接种RW8后能抑制白三叶根系伸长,根系鲜重与干重有下降趋势,但差异不显著;而幼苗的生物产量(干重与鲜重)均显著高于对照(P<0.05),并且该现象与植物生长激素IAA无关,其具体的作用机制还有待于进一步研究。

Isolation and identification of an inorganic phosphorus-solubilizing bacterium RW8 and its growth-promoting effect on white clover (Trifolium repens)

Nine strains of inorganic phosphorus-solubilizing bacteria were isolated from the rhizosphere of white clover (Trifoliumrepens),and each strain was identified to the genus and species level based on its phenotypic and cytological characteristics.The growth-promoting effect of each strain on white clover was also analyzed. Strain RW8,which showed the strongest phosphorus-solubilizing activity,was selected based on analyses of the size and ratio of its plaques and colonies.Scanning electron microscopy observations revealed that RW8 was Bacillusbrevis,a flagellated bacterium.Colonies of RW8 were opaque and had a smooth surface.In NCBI blast searches,the 16S rDNA sequence of RW8 showed 99.5% homology with that of Enterobactersp.A Bi-olog analysis suggested that RW8 had high similarity (0.610)withEnterobactercloacae.In a phosphorous-dis-solving assay,RW8 produced 424.85μg/mL dissolved phosphorus,which was possibly related to its strong or-ganic acid production (12.30μg/mL).RW8 strongly affected the biomass distribution to roots in white clover seedlings.Root elongation and the fresh weight and dry weight of roots were lower in RW8-colonized plants than in control plants,although the differences were not statistically significant.However,the seedling bio-mass (dry weight and fresh weight)of RW8-colonized white clover was significantly greater than that of control plants (P<0.05),and this phenomenon was not a result of indole acetic acid production by the bacterium. Further research is required to determine the precise mechanism of its growth-promoting effect.