青藏高原多年冻土区解磷菌筛选及抗逆能力评价

Screening of phosphorus-solubilizing strains with stress tolerance in the permafrost region of the Qinghai-Xizang Plateau

摘要:

【目的】本研究旨在从青藏高原多年冻土区土壤中分离筛选高效解磷菌，为青藏高原土壤中难利用性磷的活化提供菌株资源。【方法】以青藏高原唐古拉山口附近的多年冻土区土壤为研究对象，利用有机磷和无机磷选择性培养基通过平板划线法分离解磷菌，通过16S rRNA基因系统发育分析对菌株进行鉴定，并对解磷菌的解磷能力和抗逆能力进行评价。【结果】分离筛选的5株解磷菌应归于假单胞菌属(Pseudomonas)，包括3株解无机磷菌(i5、i6、i9L)和2株解有机磷菌(Qb和Qo)；30 ℃培养条件下，Qb和Qo上清液有效磷含量分别为534.8 mg/L和723.7 mg/L，显著高于i5、i6、i9L上清液有效磷含量(166.9–210.5 mg/L)；利用不同浓度的聚乙二醇(PEG6000)对菌株进行模拟干旱培养，5株解磷菌在PEG6000处理下均可正常生长，而且Qo上清液有效磷含量最高(519.7–683.0 mg/L)；不同培养温度下，Qb和Qo在5 ℃和10 ℃培养下解磷能力要强于其他菌株的解磷能力。【结论】菌株Qo的耐低温和干旱能力强于其他4株菌，是青藏高原等高寒地区菌肥开发和植被恢复研究重要菌种资源。

Abstract:

[Objective] To isolate efficient phosphorus-solubilizing strains from soils in the permafrost region of the Qinghai-Xizang Plateau and provide strain resources for the activation of unavailable phosphorus in the soil of the Plateau. [Methods] The selective media with organic and inorganic phosphorus were used to isolate phosphorus-solubilizing strains from the soil samples collected in the permafrost region around the Tanggula Pass of the Qinghai-Xizang Plateau by the plate streaking method. The phylogenetic tree was built based on the 16S rRNA gene sequences to identify the strains, and then the phosphorus-solubilizing abilities and stress tolerance of the strains were determined. [Results] Five strains belonging to Pseudomonas were isolated, including three inorganic phosphorus-solubilizing strains (i5, i6, and i9L) and two organic phosphorus-solubilizing strains (Qb and Qo). After 7 days of incubation in shake flasks at 30 ℃, the content of available phosphorus in the supernatants of Qb and Qo was 534.8 mg/L and 723.7 mg/L, respectively, which was significantly higher than that (166.9–210.5 mg/L) in the supernatants of i5, i6, and i9L. The available phosphorus content in the supernatant of Qo was the highest (519.7–683.0 mg/L) among the five isolates under different concentrations of PEG6000. The phosphorus-solubilizing abilities of Qb and Qo were stronger than those of the other strains at 5 ℃ and 10 ℃. [Conclusion] Qo outperformed the other strains in terms of tolerance to low temperature and drought stress, serving the development of microbial fertilizers and vegetation restoration in alpine regions such as the Qinghai-Xizang Plateau.