The infection dynamics and phase change of the Entomophathogenic Bacterium Xenorhabdus bovienii and the associated Nematode Host Steinernema feltiae.

Abstract

Injection infection of Galleria mellonella with the entomopathogenic nematode Steinernema feltiae and its symbiotic bacterium Xenorhabdus bovienii resulted in a mixed population of Stenotrophomonas maltophilia and Xanthomonas axonopidis on NBTA agar plates. 16S rRNA expression from the general Eubacteriaceae population was shown to start 18 hours after infection and it was continued until 72 hours after infection. However, the same infection was shown to result inX. bovienii 16S rRNA expression from 2 hours until 48 hours. Natural infection of 100 and 1000 S. feltiae using the same infection model resulted in a mixed population of Stenotrophomonas maltophilia and X. bovienii on NBTA agar plates. 16S rRNA expression of the Eubacteriaceae population was shown to occur between 36 and 72 hours after infection for both the 100 and 1000 S. feltiae infections. The 16S rRNA expression of the A! bovienii population began at 24 hours and 36 hours for the 100 and 1000 S. feltiae infections, respectively, and continued until 72 hours both the infection levels. The gene fragments partially encoding rpoS and FliC were isolated and cloned from X. bovienii, demonstrating that a distinction between Phase I and Phase IIX. bovienii can be attributed to the expression of the FliC gene and the rpoS gene. Isolation of a Xenorhabdus-like bacterium from the total RNA of G. mellonella indicated that an unspecified, potentially pathogenic, bacterium could be involved in the infection process in G. mellonella. Isolation of a putative Phase I specific 36.5kDa ABC transporter from Phase IX. bovienii using 2-Dimensional gel electrophoresis which could be a potential toxin transporter is a further indication of the distinction between Phase I and Phase IIX. bovienii.