四株PGPR菌株混菌发酵体系的构建及促生效应评价

Construction of Mixed Fermentation System of Four PGPR Strains and Evaluation of Its Promoting Effect

构建由4株PGPR菌株组成的混菌发酵体系并进行辣椒接种,为微生物复合菌剂的研制及开发奠定基础。通过单因素、正交实验及响应面法,优化4株菌混菌发酵的培养基和发酵条件,盆栽实验评价复合菌液对辣椒的促生效应。混菌发酵体系的最适碳氮源及比例为蔗糖∶酵母浸出物(5∶1),最适发酵条件为:温度29.7℃、pH 7.05、接种量3.19%、装液量为50 mL/250 mL;该条件下制备的复合菌液活菌数为2.94×10~(14 )CFU/mL,是单菌混合菌液的5.13倍。盆栽实验显示复合菌液显著提高了辣椒幼苗的株高、根长、鲜重及叶绿素含量,较4株菌混合菌液接种分别提高了8.01%、50.22%、43.66% 和 6.94%。利用混菌发酵体系制备的复合菌剂有更高的活菌数,可更好地发挥对辣椒的促生效应,在PGPR复合菌剂开发中潜力明显。

This objective of this work is to construct a mixed fermentation system from 4 plant growth-promoting rhizobacteria(PGPR)strains and to inoculate pepper for laying a foundation for the research and development of microbial compound agents.The medium and fermentation conditions of the mixed fermentation system were optimized by single factor experiment,orthogonal experiment and response surface method.And experiment of planting pepper in pot was conducted to evaluate the growth-promoting effect of compound broth.In mixed fermentation system,the optimal carbon source was sucrose,the optimal nitrogen source was yeast extract,and the optimal carbon-nitrogen ratio was 5∶1.The optimal fermentation conditions were as follows,temperature 29.7℃,pH 7.05,inoculation proportion 3.19%,and the medium volume 50 mL/250 mL.Under these culture conditions,the viable bacterial count in the mixed fermentation culture was 2.94×1014 CFU/mL,which was about 5.13 times compared with single strain fermentation.The growth and physiological indexes of pepper seedlings were significantly improved after irrigating with the mixed fermentation broth,i.e.,the plant height,root length,fresh weight,and chlorophyll content increased by 8.01%,50.22%,43.66%and 6.94%compared with the single strain fermentation compound.In Conclusion,the compound agents prepared by the mixed fermentation system of 4 PGPR strains may have higher viable microbial counts,and play better growth-promoting effects on pepper,and have obvious application potential in the development of PGPR compound agent.