It is hypothesized that strong gene expression will affect the growth and viability of cells. This experiment was conducted by incorporating a strong promoter from the Anderson Family (BBa_J23101: Registry of Standard Biological Parts) with a medium strength ribosome binding site (BBa_I13003: Registry of Standard Biological Parts) in Escherichia .coli (E.coli) to test the hypothesis. Quantitative results were obtained by optical density using a spectrophotometer with UV light of 600nm. The results indicated that the effect of overloading cells on growth rate was insignificant.
Introduction
Methods and Materials
Results and Interpretations
As shown in Figure 1, the DNA samples for both the experiments with strong gene expression and the negative control show similar growth rate. The results indicated that the effect of overloading cells on growth rate was insignificant. However, all the samples showed an unexpected growth pattern as they did not have a sign of reaching to a steady state. The phenomenon might be due to insufficient number of OD measurements, further investigations might be needed. Also, after approximately 235 minutes, the growth rate of all the DNA samples suddenly increased and were not consistent with the previous rates. This might due to contamination of the DNA samples which promote the growth of the cells.
Discussion
In our hypothesis, it is expected that strong gene expression will affect the growth and viability of cells. However, our results show no differences between the experimental setup with strong gene expression and the control in terms of growth rate. One possible explanation is that the promoter (BBa_J23101: Registry of Standard Biological Parts) and ribosome binding site (BBa_B0032: Registry of Standard Biological Parts) that we used in our experiments might not be strong enough and overloading of cells were not generated. Therefore, their growth rates show similar pattern.
Conclusion
Both the experimental cells and the control showed a similar growth pattern and growth rate. It is concluded that either the experimental setup did not contain a strong enough promoter and ribosome binding site to create an environment of overloading cells; or overloading of cell have insignificant effect on its growth rate. Further investigations are needed to test the hypothesis.
Effect of overloading cells on growth rate
