溶磷真菌的筛选及耐盐特性分析

【背景】土壤盐渍化已成为影响土壤质量和作物产量的重要因素之一,利用微生物改良盐渍化土壤是既经济又环保的方法。【目的】从不同土壤样品和生物肥料中筛选溶磷能力较强的真菌并讨论其耐盐能力,为盐渍化土壤改良提供菌种资源。【方法】采用平板培养法筛选有一定溶磷能力的真菌,经ITS序列分析初步确定菌株的分类地位。以溶磷能力为考察指标,以NaCl梯度和磷酸钙梯度为考察因素,分析不同菌株利用无机磷源的能力,以及溶磷能力与pH的关系。【结果】共筛选得到16株具有较强溶磷能力的真菌,其中4株真菌对水稻发芽有显著的促进作用,它们是1株长枝木霉(MF-1)和3株踝节菌属菌株(SD-2、XJ-7和HLJ-3)。菌株SD-2和XJ-7生长的耐盐能力显著好于菌株MF-1和HLJ-3。当NaCl浓度为5%时,菌株XJ-7的溶磷能力最好,溶磷率可达9.50%;当NaCl浓度为1%时,菌株HLJ-3的溶磷能力较好,溶磷率为6.93%;当NaCl浓度为0时,菌株SD-2和MF-1的溶磷能力较强,溶磷率分别为9.07%和3.73%。进一步研究发现踝节菌属真菌的溶磷能力与菌液pH呈显著负相关关系。【结论】筛选获得的4株真菌其溶磷能力在不同盐环境中有显著差异,为今后土壤改良和生物肥料中菌种的选择提供理论依据和试验基础。

Screening, identification and salt-tolerant characteristics of phosphate-solubilizing fungi

[Background] Salinity is one of the most brutal environmental factors limiting the productivity of crop plants and soil quality. There is a need to develop simple and low cost biological methods for salinity stress management. [Objective] The fungi with phosphate solubilizing properties and salt-tolerance were selected from different soil samples and biological fertilizer in order to provide good application candidate as soil remediation. [Methods] The method of plate culture was used to screen the fungi with phosphate solubilizing ability. The classification status of the strains were determined preliminarily based on internal transcribed spacer (ITS) sequence analysis. The effects of NaCl on phosphate solubilizing ability of four isolates were measured. The correlation between phosphate solubilizing capability and pH value was analyzed. [Results] A total of 16 phosphate solubilizing fungi were obtained, and 4 strains of them increased the growth of rice germination significantly, including 1 strain (MF-1) identified as Trichoderma longibarchiatum and 3 strains (SD-2, XJ-7 and HLJ-3) identified as Talaromyces. The tolerance of salt depend on different strains. The salt-tolerance of SD-2 and XJ-7 were better than MF-1 and HLJ-3. XJ-7 was able to grow in media with 5% NaCl, the P solubilizing rate was 9.50%. HLJ-3 was able to grow in media with 1% NaCl, the P solubilizing rate was 6.93%. The P solubilizing rate of SD-2 and MF-1 were 9.07% and 3.73% without NaCl, respectively. The phosphate solubilizing capability and pH value had significant negative correlation in liquid medium for Talaromyces. [Conclusion] The present study found that the phosphate solubilizing ability of 4 strains were significantly different in different saline environments. These phosphate solubilizing fungi have great application prospect as biological fertilizer in saline soil.