Invasion of insect blood tissue by Xenorhabdus bovienii

Xenorhabdus species are entomopathogenic Gram-negative bacteria that belong to the family Enterobacteriaceae. They exist in two main phenotypic variations referred to as phase I and phase II. Invasion studies showed that Xenorhabdus bovienii phase I, unlike phase II, adhered to and were phagocytosed by Drosophila melanogaster malignant blood neoplasm, mbn-2. The ingested bacteria within the phagosome multiplied and escaped into the mbn-2 cytoplasm. Further bacterial multiplication occurred within the cytoplasm with a longer postinvasion incubation period, resulting in mbn-2 lysis. X. bovienii multiplied more rapidly in artificial media than in mbn-2. The generation time of phase I X. bovienii in the artificial media was 2.5- to 3-fold that in mbn-2. Cell free extract of X. bovienii phase I fluoresced under UV light, unlike that of phase II.