小麦根际解磷细菌的筛选及其解磷能力鉴定

Isolation of phosphate-solubilizing bacteria from wheat rhizosphere and evaluation of phosphate-solubilizing capacity

分别以植酸钙和磷酸钙为磷源,利用平板稀释法从小麦根际土壤中分离筛选解磷细菌(Phosphatesolubilizing bacteria,PSB),通过16S rRNA基因测序技术鉴定其种类,并根据溶磷圈法和钼锑抗比色法对其解磷能力进行分析。结果显示:从小麦根际土壤中筛选出5株解有机磷细菌和5株解无机磷细菌,分别隶属于假单胞菌属(Pseudomonas)、芽孢杆菌属(Bacillus)、谷氨酸杆菌属(Glutamicibacter)、沙雷氏菌属(Serratia)、泛菌属(Pantoea)和肠杆菌属(Enterobacter)、拉恩氏菌属(Rahnella)、假单胞菌属(Pseudomonas)。以植酸钙或磷酸钙为磷源的菌株培养液pH均显著下降,实际磷酸酶活性范围在5.93—7.14μg∕(mL·min)或6.37—8.71μg∕(mL·min),活化出的速效磷浓度为3.5—5.3 mg∕L或34.1—69.7 mg∕L,活化率为43.3%—67.3%或30.7%—72.0%;解磷菌株对应培养液中的磷酸酶活性与pH呈现极显著的负相关关系,而与速效磷浓度呈现极显著的正相关关系。研究表明,菌株LP17和LM分别具有较强的降解有机磷和溶解无机磷的能力,隶属于芽孢杆菌属和肠杆菌属,为进一步研制高效解磷菌剂提供研究基础。

In this study,phytin and tricalcium phosphate were respectively selected as the sole P source,and the method of plate dilution was subjected to screen phosphate-solubilizing bacteria(PSB)from wheat rhizosphere.These strains at taxonomic level were identified by 16S rRNA gene sequencing technology,and phosphate-solubilizing ability of these strains was determined by method of phosphate-solubilizing halo and molybdenum blue colorimetry.The results showed that five strains of organic phosphate-solubilizing bacteria and five strains of inorganic phosphate-solubilizing bacteria were isolated from the wheat rhizosphere.According to the analysis of 16S rRNA gene sequencing,these strains were affiliated to Pseudomonas,Bacillus,Glutamicibacter,Serratia,Pantoea,Enterobacter,Rahnella and Pseudomonas.Compared with initial pH,the pH of the liquid medium with phytin or tricalcium phosphate as P source corresponding to the five strains was significantly decreased,and the actual phosphatase activity ranged from 5.93 to 7.14μg∕(mL·min)or 6.37 to 8.71μg∕(mL·min).The concentration of available P mobilized from phytin or tricalcium phosphate by these strains ranged from 3.5 to 5.3 mg∕L or 34.1 to 69.7 mg∕L,and the mobilization ratio ranged from 43.3%to 67.3%or 30.7%to 72.0%.The phosphatase activity in the corresponding liquid medium was significantly and negatively correlated with pH,while was significantly and positively correlated with available P concentration independently of P source.The strain LP17 and LM with most powerful organic and inorganic phosphate-solubilizing capability belonged to Bacillus and Enterobacter,respectively.These results provide a basis for research and development of highly effective phosphate-solubilizing bacteria.