a) Assuming that the rate of sucrose uptake is the rate limiting step in growth, which strain will grow faster if the concentration of sucrose is: 10 mM? 100 mM? 1000 mM? b) One strain was isolated from the soil and the other from the floor at Toscanini's lce Cream, which was likely to be which? Why?

B) A total of 2.5 x 105 cells were harvested from the patient. You need the cells to fill a scaffold with dimensions of 20mm x 20mm x 4mm at a final density of 2 x 104 cells/mm³. After culturing the harvested cells, you found that they have a doubling time of 36 hours. Given the growth rate is proportional to the number of cells, determine the time it will take to achieve the desired cell count. Show your work.

When present on the leaves of plants, the bacterium Pseudomonas syringae can promote frost damage to plants.  Mutant strains, lacking the “ice” gene, have been applied to plants to try and protect the plants from wild-type P. syringae-induced frost.  Assume that I am telling the truth that wild-type P. syringae nucleates ice formation at -2 °C, and provide an explanation as to why application of this altered (mutant) bacterium to plants might be a beneficial agricultural strategy in areas where morning lows occasionally dip down to 28-30 °F.

a.Describe what makes thioglycollate medium suitable for culturing anaerobes. What would the growth patterns of Clostridium sporogenes and Micrococcus luteus be in this medium?  b. In the Kligler test, why do we inoculate the surface of the agar slope and then stab into the butt of the slope? What does a pink coloured colony indicate when using MAC (MacConkey Agar)?

Below is shown a growth curve for an E. coli culture. As indicated, the culture was incubated in the absence of a carbon source for 2 hours until Glucose and Lactose were added; Glucose was used up after 5 hours, and Lactose was used up after 8 hours. During the time-course, you take four samples, labeled A-D, after 1, 3, 7 and 9 hours, respectively, as indicated under the graph. Assuming there is cAMP present at t=0, for each sample identify whether CAP and/or the Lac Repressor would be bound to the DNA, and explain why.

1) The inactivation of Staphylococcus aureus was studied in pomegranate juice heated at 75°- 95°C. The slopes for the inactivation of this bacteria were calculated from the linear lines in semi-log graphical paper. The slope values were presented in Table 1. a) Determine the temperature change needed to inactivate this bacteria by 90%. b) Temperature change to inactivate Bacillus cereus in pomegranate juice by 90% at the same temperature range was 29°F. At 75°-95°C temperature range, which bacteria will be more affected by the temperature changes? Commend on your answer in one sentence Table 1- Slope values for the inactivation of Staphylococcus aureus in pomegranate juice heated at various temperature Temp. (°C) 75 80 85 95 -Slope x 10² (min-¹) 2.222 3.704 5.000 13.158