Characterization of Serratia entomophila bacteriophages and the phage-resistant mutant strain BC4B.
1995
Grkovic S. | O'Callaghan M. | Mahanty H.K.
Successful large-scale fermentations of the bacterium Serratia entomophila for use in biological control of the soil-dwelling insect Costelytra zealandica has required the development of a phage-resistant mutant, BC4B. We report our investigations into S. entomophila phages and the nature of the phage resistance mechanism of strain BC4B. The parental strain of BC4B, A1MO2, was found to contain two previously unidentified prophages, phi 9A and phi 9B, which were UV inducible and also released spontaneously in large numbers. BC4B was shown to be completely cured of phi 9A. Single lysogens of phi 9A and phi 9B were not homoimmune to any other S. entomophila phages. However, on the basis of DNA-DNA homology, all S. entomophila phages except phi CW3 were shown to have significant regions of homology and also packaged their DNA via pac-like mechanisms. The failure of phage particles to adsorb was identified as the basis of phage resistance in BC4B. In addition, it was demonstrated that all known S. entomophila phages are naturally temperature sensitive.
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