| Summary: | 碩士 === 東吳大學 === 微生物學系 === 100 === Previous studies in our laboratory found that the Vibrio
parahaemolyticus formed shape variation at the beginning of inducing the
cells into the Viable But Non-Culturable (VBNC) state by incubation the
cultures in starvation medium at low temperature. It may be due to the rapid
synthesis of cytoskeletons in that stage, for example, expression of
ftsZ increased by 10-folds, and mreB increased by more than 5-folds.
However, the aberration of bacterial cell shape may also attribute to the
damage of cell wall and forms a weakened site at the cell wall and the tension
of the cytoplasm will cause the bulging of cells at that site to form cells with
different shapes.
Therefore, this study first determined the optimum conditions to
generate cultures with the largest proportion of shape variations. Then, this
study determined the effect of certain antibiotics on the variation of cell
shapes, and the results showed that the antibiotics used (D-cycloserine、
Cephalosporin C) only formed filamentatous cells, but without other
variations in cell shape.
We further determined the expressions of selected genes by Quantitative
real time polymerase chain reaction，Q-PCR) and the results demonstrated
that a gene (VP2468) encoding L,D-Carboxypeptidase (DacB) was over
expressed during the initial stage of VBNC induction. An isogenic mutation
of tis VP2468 was made and exhibited significantly lowered ratio of aberrant
shaped cells. However, in the mutant culture with a complementary gene with
exhibited formal expression of the transcripts and proteins, the lowered ratio
of aberrant shaped cells did not recover. It is postulated that the mutation of
this VP2468 gene may influence the expression and function of some other
genes which are not fully recovered in the complementary strains. Further
study is needed to clarify the role of VP2468 in the cell shape of this
pathogen under the VBNC induction condition.
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