祁连山云杉林土壤溶磷细菌的分离及对白三叶的促生效应

Isolation of Phosphate Solubilizing Bacteria from Soil of Spruce Forest in the Qilian Mountains and Their Growth Promotion Effects in White Clover

为获得具有促进牧草白三叶(Trifolium repens L.)生长能力的优良溶磷细菌(Phosphate solubilizing bacteria,PSB)资源,本研究以祁连山青海云杉林(Picea crassifolia)根际土壤细菌为研究对象,采用平板定性与钼锑抗比色定量分析、系统进化分析和植物盆栽接种试验,探究了上述根际土壤所分离菌株的溶磷能力、分类地位和对白三叶生长的影响。结果表明:筛选得到的12株PSB菌株在难溶性无机磷(National botanical research institute phosphorus,NBRIP)平板上的溶磷圈直径/菌落直径的比值范围为1.44~2.40。12株PSB菌株均归属于假单胞菌属(Pseudomonas sp.)。在上述基础上,选取的5株菌株在NBRIP液体培养基培养96 h后,发酵液的可溶性磷含量范围为387.41~479.87μg·mL^(-1),其中菌株LT-4发酵液的可溶性磷含量最高。植物接种试验结果表明,与空白对照相比,接种菌株LT-4能显著提高白三叶的生物量,植株地上部和根干重分别显著增加87.01%和74.83%。本研究为进一步探究溶磷细菌的促生机理以及开发应用于栽培牧草的微生物菌剂或菌肥奠定了一定的前期工作基础。

In order to obtain excellent phosphate solubilizing bacteria(PSB)strains that could promote the growth of white clover(Trifolium repens L.),soil collected from spruce forests(Picea crassifolia)in the Qilian Mountains were served as our research object in this study.We used phosphate-dissolving qualitative and quantitative methods,phylogenetic analysis and plant inoculation experiments to investigate the phosphate solubilizing ability,taxonomic status of PSB strains and evaluate their inoculation effects on the growth of white clover.The results showed that the ratio of the diameters of the halo to the colony on NBRIP plates of 12 PSB strains were ranging from 1.44 to 2.40.These strains were further identified and classified as Pseudomonas sp..On the basis of above data,the soluble phosphorus content of 5 selected PSB strains was ranging from 387.41μg·mL^(-1) to 479.87μg·mL^(-1) in the NBRIP liquid medium after 96 hours of incubation.The content of soluble phosphorus in the fermentation broth of strain LT-4 was the highest in all strains.In addition,we observed that the application of strain LT-4 significantly improved the growth of white clover compared to DH5αand water treatment,respectively,especially,shoot and root dry weight significantly increased by 87.01%and 74.83%.These results could lay a foundation for further exploring the regulatory mechanism and high-efficiency biofertilizer for forage cultivation.