Diversity and antimicrobial activity of endophytic bacteria isolated from Lycium barbarum of Ningxia

Abstract:

[Objective] The purpose of this study was to investigate the distribution, diversity and antimicrobial activity of endophytic bacteria of Lycium barbarum L. of Ningxia. [Methods] The 16S rRNA gene sequencing and agar diffusion were employed to explore the diversity and antimicrobial activity of endophytic bacteria isolated from different organs and tissues of Lycium barbarum L.. [Results] Total of thirty-four isolates were obtained. The result of diversity analysis showed that these isolates could be phylogenetically classified into 11 genera and 7 families, based on their 16S rRNA gene sequencing. The quantity and clonal composition of bacterial communities were distinct from various tissues. The quantity of endophytic bacteria in the different tissues was in order of roots > leaves > flowers > fruits; the diversity of bacteria was flowers > roots > leaves > fruits. Additionally, Bacillus spp. was a predominant species and was isolated in all tested tissues. Analysis of antimicrobial activity demonstrated that 76.5% of isolates had an antimicrobial activity against at least one of the five tested pathogenic bacteria, among which Bacillus R2, R7, L3 and Brevundimonas R3 displayed significant antimicrobial activity against the plant pathogens Colletotrichum nigrum and Exserohilum turcica. Of note, the majority of isolates showed weak inhibition effect against Escherichia coli and Staphylococcus aureus. [Conclusion] Endophytic bacteria of Lycium barbarum L. are genetically diverse and most of them have a strong inhibitory activity against plant pathogenic fungi.