*The function of alkaline phosphatase* and the specific phosphate transport protein in Escherichia coli
Phosphate is an essential nutrient for all living organisms. It is used to synthesise ATP, nucleic acids and cell membranes. Microorganisms such as E. coli obtain it mainly from inorganic phosphate ions (Pi) as well as some phosphate-containing organic molecules. These molecules can enter the periplasmic space easily but must be taken across the inner membrane by transport proteins. (Black 2005)
If an E. coli cell lacks alkaline phosphatase it is unable to breakdown organic molecules for transport into the cell and with a mutated phosphate transport protein phosphate molecules cannot enter the cell. These two mutations will be examined in this practical.
To examine the function of alkaline phosphatase and the specific phosphate transport protein in E.coli to discover the genotype of four unknown strains.
Materials and methods
Refer to the 2009 Molecular Biology Practical manual pages 52 and 53
after the samples were plated they are not taped before being incubated for a week Results
There was differing amounts of growth in the strains after each had been incubated for a week (Table 1). Samples that did not grow demonstrate a mutation in the specific phosphate transporter. This phenotype was seen in strains number 1 and 2. All strains on G3P plates grew in varying amounts showing that all samples have another functioning pathway to gain phosphate.
Table 1: Results for E. coli grown on Pi and G3P plates after one week incubation
After alkaline phosphatase (PNPP) was added to the E. coli samples those strains whose cells contained phosphate turned a yellow colour. The table below (table 2) demonstrates that strains 1 and 3 contained phosphate so had an active phosphate transport system while 2 and 4 did not.
Table 2: Results found ten minutes after PNPP was...