Isolation,identification and functional analysis of intestinal bacteria of Spodoptera frugiperda

【Objective】To clarify the species and functions of intestinal bacteria of Spodoptera frugiperda and explain the effects of intestinal bacteria on the adaptability of S. frugiperda to host plants,so as to provide a theoretical basis for revealing the host adaptation mechanism of S. frugiperda and predict the expansion trend of host spectrum.【Method】The intestinal bacteria of S. frugiperda were isolated and purified using the microbial isolation and purification methods,and the 16S rRNA gene sequence homology analysis was performed on the isolated bacterial strains. The strains that produced cellulase,xylanase,pectinase and metabolized phenol were preliminarily screened. And the cellulase,xylanase,pectinase production activities and metabolism of phenol were analyzed through DNS method. The strains were cultured in phenolcontaining inorganic salt medium to detect their phenol degradation efficiency.【Result】A total of 45 bacterial strains were isolated by comparative homologous sequence analysis,and they belonged to 5 genera of Firmicutes,Proteobacteria,and Acinobacteria,namely,Staphylococcus,Bacillus,Klebsiella,Acinetobacter and Colletotrichum,among which Klebsiella had the highest abundance. Among the 45 strains,11 strains could produce cellulase and K3 of Klebsiella had the highest enzyme activity of 0.105±0.007 U/mL;10 strains could produce xylanase and B9 of Bacillus had the highest enzyme activity of 1.090±0.468 U/mL;5 strains could produce pectinase K27 of Klebsiella had the highest enzyme activity of 0.193±0.047 U/mL;9 strains could degrade phenol and B8 of Bacillus had the highest degradation rate of(0.347±0.042)%.【Conclusion】 Diversity of enzyme-producing strains of intestinal bacteria in S. frugiperda larvae is speculated to be one of the reasons for the wide host spectrum and serious damage to the host.