Effect of Growth Media on Phase Variation in Xenorhabdus bovienii T228

DOI: 10.5176/2251-2489_BioTech13.82

Authors: Owuama, Chikezie I.

Abstract:

Xenorhabdus species are entomopathogenic bacteria that exhibit phase variation, existing in two main phases, phase I and phase II. Galleria mellonella larval haemolymph apparently contains substance(s) that influence the change of X. bovienii strain T228 phase II to phase I. Growth of phase II in nutrient broth or Luria-Bertani broth at 28C for 48 h revealed no change in phase. But incubation of X. bovienii phase II in nutrient broth or Luria-Bertani broth supplemented with haemolymph, or haemolymph alone in a closed tube for 48 h resulted in a change into phase I. Also, X. bovienii phase II incubated for 48 h in Schneider medium supplemented with 10{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} foetal bovine serum yielded phase I revertants. Revertants showed phase I characteristics viz., adsorbed dyes, produced pigments and were ampicillin resistant. X. bovienii phase I revertants adhered to Drosophila melanogaster malignant blood neoplasm, mbn-2, were internalized, multiplied within the cytoplasm and lysed the insect cell lines. Specific phase altering factor(s) responsible for phase change is yet to be identified but are apparently present in insect and bovine bloods.

Keywords: Xenorhabdus, phagocytosis, Phase Variation, Drosophila, Galleria.