Difference between revisions of "Part:BBa K3585006"

Revision as of 02:49, 27 October 2020

J23200-lacY

In E. coli, the presence of glucose inhibits the synthesis of many catabolic enzymes, a phenomenon called "glucose effect" or "glucose inhibition". Studies have shown that overexpression of LacY can eliminate the glucose effect. We use the strong promoter J23200 to continuously overexpress the lacY protein to achieve simultaneous metabolism of glucose and galactose, thereby improving the efficiency of degrading galactose.

Sequence and Feature

contribution

BBa_K3585006 is a composite part constituting of constitutive promoter (basic parts BBa_J23100) and LacY gene. LacY codes for beta-galactoside permease which regulates the transport of lactose into the cell. BBa_K3585006 is designed to production of beta-galactoside permease on the cell membrane which enables the cell to use lactose as the carbon source.

engineering success

The BBa_K3585006 was designed to produce beta-galactoside permease on the cell membrane which enables the cell to use lactose as the carbon source.

To test our design, we made the following experiments and presented the results as follows:

Supporting growth of bacteria expressing lacY in galactose Bacteria with lacY was able to grow using galactose as the unique carbon source in the culture, although the growth rate of the host bacteria is obviously slower than those strains cultured with glucose.

Figure 1

Figure 1. Growth rate of host strains when supplied with different carbon sources. Each of the strains we have a repeat. Glu represents that we use glucose as the carbon source while fermentation; Gal represents that we use galactose as the carbon source while fermentation; GG represents that we use both glucose and galactose as the carbon source while fermentation; 1917 represents wild type strains; pButy represents that the host strain contained pMTL83151-J23100-butyrate plasmids and expressed butyrate synthesis gene cluster; placY represents that the host strain contained p15A-J23200-lacY plasmids and expressed lacY gene; 1 and 2 represent for sample repeats.

Accelerating consumption rate of galactose When the medium contained only galactose, the host bacteria expressing lacY gene began to consume lactose at 4 hours, indicating that lacY gene could promote the consumption of galactose by the host bacteria.

Figure 2

Figure 2. Consumption rate of galactose. Each of the strains we have a repeat. Gal represents that we use galactose as the carbon source while fermentation; GG represents that we use both glucose and galactose as the carbon source while fermentation; 1917 represents wild type strains; pButy represents that the host strain contained pMTL83151-J23100-butyrate plasmids and expressed butyrate synthesis gene cluster; placY represents that the host strain contained p15A-J23200-lacY plasmids and expressed lacY gene; 1 and 2 represent for sample repeats.

According to the experiments results and figures, the BBa_K3585006 is functional in producing beta-galactoside permease.