Isolation, characterization, and antimicrobial activity of endophytic bacteria from Polygonum cuspidatum

Abstract

Polygonum cuspidatum Sieb. et Zucc. is a traditional Chinese medicinal plant that produces polydatin, a glycosylated derivative of resveratrol. Thus far, 244 prokaryotic endophytes have been isolated and identified from P. cuspidatum using 16s rDNA sequence. The results show that the endophytic bacteria in P. cuspidatum belong to five orders, namely, Actinomycetales, Bacillales, Rhizobiales, Pseudomonadales, and Enterobacteriales. At the genus level, 244 strains were identified, including Lysinibacillus, Paenibacillus, Pseudomonas, Bacillus, Kocuria, Streptomyces, Providencia, Rhizobium, Leucobacter, Brachybacterium, and Mycobacterium. These bacteria were classified into 36 groups based on their 16s rDNA sequence. The endophytic bacteria isolated from P. cuspidatum show inhibitory activity against pathogenic fungi and bacteria. Among them, 13 isolates showed inhibitory activity against Gibberella fujikuroi, 18 isolates againstAspergillus niger, 6 isolates against Aspergillus fumigatus, 4 isolates against Klebsiella pneumoniae, 12 isolates against Staphylococcus aureus, and 6 isolates against Bacillus subtilis. However, none of the bacteria inhibited Escherichia coli.   Key words: Polygonum cuspidatum, endophytic bacteria, phylogenetic analysis,antimicrobial activity.