Identification of a NewAlcaligenes faecalisStrain MOR02 and Assessment of Its Toxicity and Pathogenicity to Insects

摘要

We report the isolation of a bacterium fromGalleria mellonellalarva and its identification using genome sequencing and phylogenomic analysis. This bacterium was namedAlcaligenes faecalisstrain MOR02. Microscopic analyses revealed that the bacteria are located in the esophagus and intestine of the nematodesSteinernema feltiae, S. carpocapsae, andH. bacteriophora. UsingG. mellonellalarvae as a model, when the larvae were injected with 24,000 CFU in their hemocoel, more than 96% mortality was achieved after 24 h. Additionally, toxicity assays determined that 1 μg of supernatant extract fromA. faecalisMOR02 killed more than 70%G. mellonellalarvae 96 h after injection. A correlation of experimental data with sequence genome analyses was also performed. We discovered genes that encode proteins and enzymes that are related to pathogenicity, toxicity, and host/environment interactions that may be responsible for the observed phenotypic characteristics. Our data demonstrates that the bacteria are able to use different strategies to colonize nematodes and kill insects to their own benefit. However, there remains an extensive group of unidentified microorganisms that could be participating in the infection process. Additionally, a nematode-bacterium association could be established probably as a strategy of dispersion and colonization.