植物根际促生菌可以分解转化土壤中的有机质和矿物质,预防和控制农作物病害,减少农药和化肥的使用,将其应用于农业被认为是一种提高农作物产量的新型方法.实验室分离筛选到一株优良的解淀粉芽孢杆菌L-H15,通过前期L-H15全基因组测序的提示,考察L-H15能够产生的促生物质,并优化其发酵工艺,开发出高活性的固态菌剂.结果表明:解淀粉芽孢杆菌L-H15能够产生相对表达量为65.53％的铁载体;其产1-氨基环丙烷-1-羧酸脱氨酶的能力也较强,比活力测定结果为0.401 U/mg;采用酶联免疫吸附法检测到该菌株亦能产生植物激素吲哚乙酸和细胞分裂素,产细胞分裂素的能力尤为显著,可达到2.157 7×10-10 mol/L;运用气相色谱-质谱检测出L-H15产生的挥发性物质中含有乙酰甲基原醇.这些因素均可有效刺激植物的生长发育.采用Box-Behnken响应面试验优化解淀粉芽孢杆菌L-H15的发酵工艺,L-H15的最佳发酵条件为:接种量8％、装液量67.8％、发酵时间11.5 h、发酵温度32℃、转速196 r/min.此时,解淀粉芽孢杆菌L-H15活菌数最高可达到1.21×109 CFU/mL.综合评定,解淀粉芽孢杆菌L-H15是一株优良的植物根际促生菌,具有广阔的开发成生物肥料的前景.%Plant growth promoting rhizobacteria (PGPR) can decompose and transform organic substances and minerals in soil,prevent and control plant diseases and reduce the use of pesticides and fertilizers.Thus,PGPR are considered to be used as a new strategy to improve agricultural production.Bacillus amyloliquefaciens L-H15 is an excellent plant growth promoting rhizobacterium.Based on the results of previous studies of its full-length genomic sequence,we investigated the plant growth promoting properties of B.amyloliquefaciens L-H15 and optimized its culture conditions in order to develop a highly active solid starter culture.Our results indicated that B.amyloliquefaciens L-H15 produced a high level of siderophore (65.53％) and strong activity of 1-aminocyclopropane-l-carboxylate (ACC) deaminase showing a specific activity of 0.401 U/mg.This strain could also produce indole-3-acetic (IAA) and cytokinins (CTK).The ability to produce CTK was particularly significant,which was as high as 2.157 7 × 10-10mol/L.Acetyl methyl alcohol,which can promote plant growth,was also detected in the volatiles generated by L-H15.These factors were able to effectively stimulate plant growth.We used response surface methodology based on Box-Behnken design to optimize the culture conditions of B.amyloliquefaciens L-H15 as follows:an inoculum size of 8％,a proportion of medium in a 500-mL volumetric flask of 67.8％,a culture temperature of 32 ℃,a culture time of 11.5 h,and a rotational speed of 196 r/rain.Under these conditions,the viable cell count ofB.amyloliquefaciens L-H15 was 1.21 × 109 CFU/mL.In conclusion,B.amyloliquefaciens L-H15 is an excellent PGPR,which has a broad prospect of development and utilization as a biofertilizer.
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