生姜根际解磷芽孢杆菌的筛选及其促生效应评价

Screening of phosphate-solubilizing Bacillus from the ginger rhizosphere and evaluation of its growth-promoting effects

【目的】筛选和鉴定生姜根际解磷芽孢杆菌,并评估其解磷能力及促生效应,为生姜根际解磷芽孢杆菌菌种资源的挖掘和微生物肥料的开发利用提供理论依据。【方法】以296株生姜根际芽孢杆菌为供试菌株,通过无机磷选择性培养基筛选出能高效水解磷酸钙的菌株;通过室内试验,分析解磷菌株的溶磷活性和生长素(IAA)产生能力;通过温室盆栽试验,评估解磷菌株对玉米和生姜的促生效应及其对根际土壤速效磷含量的影响;结合形态学观察、生理生化特性测定及16S rRNA序列分析,确定解磷菌株的分类地位。【结果】从296株生姜根际芽孢杆菌中筛选出6株具有良好溶磷活性的芽孢杆菌,分别为菌株L9、L11、L12、L54、HC-5和C42。室内试验结果表明,接种后第5 d,6株菌株发酵液内可溶性磷含量达峰值,范围在118.90~179.33 mg/L;振荡培养48 h后,6株菌株发酵液内IAA含量为2.09~3.49μmol/L。通过分析NBRIP培养液中可溶性磷含量与pH的关系,发现在接种后的1~5 d内,可溶性磷含量与pH存在显著负相关(P<0.05,下同)。种子萌发试验结果显示,C42和L54菌株显著提升了玉米种子的发芽率和发芽势。在温室盆栽条件下,菌株L54和L11在促生玉米植株生长和溶磷能力方面效果较优。与空白对照相比,经L54和L11菌株处理后,玉米的株高、叶长、根长、地上部鲜重、地下部鲜重和地上部干重增加11.11%~88.89%,根际土壤速效磷含量分别增加49.29%和42.46%;同样,经L54和L11菌株处理后,生姜的株高、地上部鲜重和姜块鲜重显著增加17.94%~42.06%,根际土壤速效磷含量分别增加73.80%和69.45%。经鉴定,这6株解磷菌株均属于贝莱斯芽孢杆菌(Bacillus velezensis)。【结论】从生姜根际芽孢杆菌中筛选得到6株具有良好溶磷能力的贝莱斯芽孢杆菌,这些菌株能有效促进玉米和生姜植株生长,还能增加玉米和生姜根际土壤中的速效磷含量,具备开发为微生物肥料的潜力。

【Objective】This study aimed to screen and identify phosphate-solubilizing Bacillus strains isolated from the ginger rhizosphere,and evaluate their phosphorus solubilization ability and growth-promoting effect,thereby providing a theoretical basis for the exploration of phosphate-solubilizing Bacillus resources in ginger rhizosphere and the de‐velopment and utilization of microbial fertilizers.【Method】Using 296 Bacillus strains in ginger rhizosphere as the test strains,strains capable of efficiently hydrolyzing calcium phosphate were screened through an inorganic phosphorusselective media.Through indoor experiments,the phosphorus solubilization activity and auxin(IAA)production capacity of phosphate-solubilizing strains were analyzed.A greenhouse pot experiment was conducted to evaluate the growth-promoting effects of phosphate-solubilizing strains on maize and ginger and their impacts on the available phosphorus con‐tent in rhizosphere soil.The classification status of phosphorous solubilizing strains was determined based on morphologi‐cal observation,physiological and biochemical characteristics tests,and 16S rRNA sequence analysis.【Result】Six strains with notable phosphorus solubilization activity were screened from the 296 Bacillus strains in ginger rhizosphere,namely strains L9,L11,L12,L54,HC-5 and C42.Indoor experimental results revealed that after 5 d of inoculation,the soluble phosphorus content in the fermentation broth of the 6 strains reached their peak,with a concentrations range of 118.90 to 179.33 mg/L.After 48 h of shaking culture,the IAA content in the fermentation broth of the 6 strains ranged from 2.09 to 3.49μmol/L.By analyzing the relationship between the soluble phosphorus content and pH value in the NBRIP culture liquid,it was discovered that there was a significant negative correlation between the soluble phosphorus content and the pH value within 1-5 d after inoculation(P<0.05,the same below).Seed germination test results showed that strains C42 and L54 significantly increased the germination rate and germination potential of maize seeds.Under greenhouse pot condi‐tions,strains L54 and L11 showed better performance in promoting maize plant growth and phosphorus solubilization ability.Compared with the blank control,the plant height,leaf length,root length,shoot fresh weight,root fresh weight and shoot dry weight of maize treated with strains L54 and L11 increased by 11.11%-88.89%,and the available phosphorus content in rhizospheric soil increased by 49.29%and 42.46%respectively.Similarly,after treatment with strains L54 and L11,the plant height,shoot fresh weight and ginger tuber fresh weight also increased significantly by 17.94%-42.06%,and the available phosphorus content in the rhizospheric soil increased by 73.80%and 69.45%respectively.After identifi‐cation,all 6 phosphate-solubilizing strains were B.velezensis.【Conclusion】The 6 B.velezensis strains screened from the ginger rhizosphere show excellent phosphate-solubilizing ability,these strains can effectively promote the growth of maize and ginger plants,and increase available phosphorus content of maize and ginger rhizospheric soil,thus possess the potential to be developed as microbial fertilizers.