You are a graduate student working to construct a single gene knockout library of Leptospiria kirschneri, one the causative agents of leptospirosis

You are a graduate student working to construct a single gene knockout library of Leptospiria kirschneri, one the causative agents of leptospirosis. You are looking for single gene mutants which disrupt the bacterium's spirillum shape to determine what role this rare cellular morphology may play in disease development and progression. Using an appropriate donor strain, you introduce the plasmid shown into L. kirschneri. L. kirschneri is not able to replicate the plasmid. The repeat regions are denoted on the plasmid map as vertical black lines, the transposase is denoted as tnp, and kanamycin kinase is denoted as aph. The larger of the two regions is transposed. Following selection and counter-selection, you isolate several non-spirillum colonies, which you use to infect juvenile piglets. Most of the infected piglets develop leptospirosis. Isolating L. kirschneri from these animals reveals that it has regained its spirillum morphology. What is a likely explanation for this reversion of morphology?

A)The transposon was lost when the plasmid failed to replicate
 B)The transposon excised from its original site of integration and integrated into a different position in the chromosome.
C) The genes regulating cellular morphology are only expressed during active infection
D) The bacterium acquired a mutation which inactivated the transposon
E) The bacterium never integrated the transposon