一株根际解磷菌的筛选鉴定及溶磷促生作用

Isolation and identification of a rhizosphere phosphate-solubilizing strain and its plant growth promotion

从黄河三角洲地区盐碱化耕地的5种农作物根际土壤中分离筛选高效解磷菌,为开发盐碱地生物肥料提供菌种资源。结合解磷圈筛选法和钼锑抗比色法评价菌株的解磷能力;采用含不同NaCl浓度的LB培养基测定菌株的耐盐性。利用菌株的形态学特征、生理生化特性和16S rDNA基因序列分析方法进行鉴定;采用液体摇床培养试验测定菌株对多种难溶性磷源的溶解能力。以盐碱化土壤为供试土壤,检验菌株在盐碱土壤中的应用潜力。共分离出27株解磷细菌,其中菌株B19被鉴定为杓兰泛菌(Pantoea cypripedii),该菌在0%~4%的NaCl浓度下生长良好,最高可耐受6%的盐浓度。B19具有较强的解磷能力,在Ca_(3)(PO_(4))_(2)为磷源的无机磷固体培养基上30℃培养3 d解磷圈的直径(D)为18 mm,与菌落直径(d)比达3.17;PVK液体培养试验表明,菌株B19对多种难溶性磷源都有较强的溶解能力,对Ca_(3)(PO_(4))_(2)、AlPO_(4)、FePO_(4)和磷矿粉溶磷量分别达230.2、72.1、153.2和28.5 mg/L。土壤培养试验结果表明,B19菌可以显著提高盐碱化土壤的有效磷含量,10 d后土壤有效磷含量增加了36.2%。盆栽试验结果还表明,B19菌对小麦植株促生效果显著,说明解磷菌B19在改善盐碱化土壤肥力方面具有很好的应用潜力。

Rhizosphere soils of crop in the Yellow River Delta were collected to isolate high-efficiency phosphatesolubilizing bacteria to obtain microbes for bio-fertilizer production for saline-alkali soil.PVK solid medium was used to screen phosphorus-soluble bacteria by transparent circle method;16S rDNA sequence analysis combined with morphological characteristics were used to identify strains;LB medium containing different NaCl concentrations were used to determine the salt tolerance of the bacteria;liquid culture experiment was used to determine the ability of dissolving insoluble phosphorus sources.The phosphorus solubilizing efficiency of the strain was investigated in saline-alkail soil.A total of 27 phosphatesolubilizing bacteria were isolated and B19 identified as Pantoea cypripedii,was selected for further study.Pantoea.cypripedii B19 grows well at 0%~4%NaCl concentration and can tolerate salt concentration up to 6%.B19 had good phosphatesolubilizing capacity.When cultured on PVK solid medium at 30℃for 3 days,the diameter of the solubilizing halo zone(D)was 18 mm,which was 3.17 times of the diameter of the colony(d);B19 could effectively dissolve Ca_(3)(PO_(4))_(2),AlPO_(4),FePO_(4) and phosphate rock powder,and released 230.2,72.1,153.2 and 28.5 mg/L phosphorous in the PVK liquid medium,respectively.The results of soil culture experiments showed that strain B19 significantly increased the level of available phosphorus by 36.2%in saline-alkali soil after 10 days.The results of pot experiment showed that the B19 had obvious promoting effect on the growth of wheat seedlings,which indicates that B19 is a promising candidate to develop biofertilizer suitable for saline-alkali soils.