甘草根际功能芽孢杆菌的分离、筛选及鉴定研究OA

Rhizosphere soil microorganisms are closely linked to plant growth,development,yield,and quality.To better exploit the functional Bacillus resources in the rhizosphere of medicinal plants,five Bacillus strains from the rhizosphere soil of Glycyrrhiza uralensis Fisch.were isolated and purified.Identification based on morphological,physiological,biochemical characteristics,and 16S rRNA gene sequencing revealed that strain G1-a was Bacillus haynesii,strains G1-E,G5-1,and G5-2 were Bacillus atrophaeus,and strain G6-f was Bacillus circulans,with each strain further assessed for enzyme production and biocontrol potential.Strains G5-1,G6-f,and G1-E demonstrated the ability to produce amylase and protease,while strains G5-1,G6-f,and G5-2 also exhibited strong capabilities in solubilizing potassium,dissolving phosphorus,and inhibiting pathogens.Strain G6-f showed the most effective antagonistic activity against Fusarium equiseti,Fusarium sambucinum,and Fusarium solani.All five Bacillus strains displayed potential for nitrogen fixation,biofilm formation,and indole-3-acetic acid(IAA)secretion,with G5-1,G5-2,and G1-a additionally capable of producing siderophores.The isolated strains were able to grow under conditions of 2%-10%NaCl,pH 4-10,and temperatures ranging from 4℃to 48℃,among which G5-1,G5-2,and G6-f exhibited strong tolerance to saline-alkaline and high-temperature environments.In summary,these five Bacillus strains demonstrate excellent properties in enzyme production,phosphorus solubilization,antagonism,nitrogen fixation,saline-alkaline tolerance,and pathogen inhibition.This study provides high-quality strain resources and a theoretical foundation for the development of microbial fertilizers and biocontrol agents for Chinese herbal medicine.