The Influence Of The Venom Of Solenopsis Invicta Buren On The Bacterial Community In Nest Soil

Insect bacterial symbionts contribute to many essential biological functions of insects and can also influence fecundity.A major physiological contribution made by endosymbionts is the ability to improve immune responses and xenobiotic detoxification.Both of these factors can directly impact biological and chemical control strategies.The red imported fire ant,Solenopsis invicta Buren,is a worldwide invasive pest that causes serious damages to agricultural and forestry production,human and animal safety,public facilities and biodiversity.Fire ants may directly or indirectly influence the microbial diversity of the nest soil during the invasion process.In this study,high-throughput sequencing technology was used to study the diversity of the bacterial community in the fire ant nest soil,and changes in the diversity and richness of bacterial community in the nest soil that was treated with fire ant venom.The isolated strain was tested for venom bacteriostasis.The composition of bacterial community in the nest soil,the effect of fire ant venom on the diversity of bacterial community,and the sensitivity of the isolated strain to the venom were determined.The research results are as follows:1.Diversity of bacterial community in nest soil: Total DNA of nest soil and control soil was extracted for PCR amplification of the V3-V4 region of the bacteria 16 S r DNA.The amplified products were then subjected to sequence analysis.The results showed that the diversity and richness of bacterial community in nest soil is higher than that in control soil.The ant nest soil is relatively moist and acidic.The dominant phyla of nest soil and control soil were Proteobacteria(33.59%?34.65%),Chloroflexi(19.41%?21.12%),Acidobacteria(13.16%?15.86%),Actinobacteria(11.26%?14.78%).The relative abundance of Bacteroides in nest soil was significantly higher than that in control soil(P < 5%).In contrast,the relative abundances of Microgrnomates,Ignavibacteriae,Peregrinibacteria,RBG?1?Zixibacteria and Gracilibacteria in control soil were significantly higher than those in nest soil(P < 5%).At the level of 1%,the relative abundance of the Phytophthora in control soil was significantly higher than nest soil.At genus level,the dominant genus is Acidobacteria and the subdominant genus is Anaerolineae.The relative abundances of Acidibacter,BIrii41,and Mycobacterium in nest soil were significantly higher than those in control soil(P < 1%).2.The effect of fire ant venom treatment on the diversity of bacterial community in the control soil.The experimental results show that after treatment with venom,the diversity of bacterial communities in the soil decreases and the species richness of the communities decreases significantly.At the phylum level,the predominant phylum was Proteobacteria and the subdominant phylum was Chloroflexl.The relative abundances of Firmicutes and GAL15 in the treatment soil were significantly higher than those in the control soil,whereas the relative abundances of Cyanobacteria and Ignavibacteriae in the control soil were significantly higher than those in the treatment soil.Ignavibacteriae disappeared when the soil was treated with 220 ?g/m L venom.At genus level,the dominant genus is Acidobacteria and the subdominant genus is Anaerolineae.The relative abundances of Anaerolineaceae,Nitrosomonadaceae,Gemmatimonadaceae,Roseiflexus,Haliangium,Ardenticateni,Polycyclovorans in the control soil were significantly higher than those in treatment soil.In contrast,the relative abundances of Bacillus,Xanthobacteraceae,Rhodobiaceae in the treatment soil were significantly higher than those in the control soil.3.Effects of the fire ant venom treatment on the diversity of bacterial community in the nest soil.The experimental results show that after treatment with venom,the diversity of bacterial communities in the soil decreases and the species richness of the communities decreases significantly.At phylum level,the predominant phylum in the nest soil was Proteobacteria and the subdominant phylum was Actinobacteria.When treated with fire ant venom,the relative abundance of soil bacterial community varied greatly at phylum level,such as Chloroflexi,Firmicutes and WS2.The relative abundances of Mycophyta and WS2 decreased significantly,but the relative abundance of Firmicutes increased significantly.Microgenomate,Cholorobia and Fibrobacteres disappeared after treatment of the nest soil with 220 ?g/m L venom,indicating that they were sensitive to the venom.At genus level,the dominant bacteria in the treatment soil and the nest soil was Acidobacteria and the subdominant bacteria was Anaerolineae.In the nest soil,the relative abundance of Anaeroline was significantly higher than that in the treatment soil.When the nest soil was treated with the ant venom,the relative abundances of Enterobacter,Bacillus,Streptomyces,Lactococcus,Pantoea and KD4-96 in treatment soil were significantly higher than those in nest soil.The relative abundances of Enterobacter,Anaerolineaceae,Bacillus,Acidobacteria,Sphingomonas,Acinetobacte decreased significantly with the increase of the venom concentration.4.The sensitivity of the bacteria isolated from the ant nest soil to the fire ant venom.16 species from 5 genera in 4 families,were identified from the nest soil.The 5 genera included Lysinibacillus and Bacillus(Bacillaceae),Sinomonas(Micrococaceae),Enterobacteriaceae(Enterobacter),Burkholderiaceae and Burkholderia(Burkholderiaceae).Among the 16 species,the growth of 10 species was inhibited by the venom,but the growth of the remaining 6 species was not affected by the venom.When the venom at a concentration equivalent to the concentration of the venom in the nest soil did not show significant inhibitory effect on any species.The growth of Bacillus species 1-5 was significantly inhibited by the venom at high concentrations.Fire ant venom had no inhibitory effect against all other species.