lag phase

If the generation time of Escherichia coli is 30 minutes, starting with 4 E. coli cells, how many cells can you obtain after 2 hours of growth? A: cells

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.

The table below is from the lethal effects of heat for E. coli. What is the TDP for this organism? (Please include the unit.)

Using a solid line draw a standard bacterial growth curve. Represent all the phases by numbering them and describe what is going on with the bacteria at each phase.

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

What is the best explanation for why a bacteriostatic treatment might be chosen over a bacteriocidal treatment? Bacteriostatic treatments will eliminate all bacteria while bacteriocidal treatments will only eliminate a portion of the bacteria. Bacteriostatic treatments typically have lower toxicity to the host when compared to bacteriocidal treatments. Bacteriostatic treatments will prevent all bacterial growth, while bacteriocidal treatments will permit some bacterial growth. Bacteriostatic treatments are typically more costly than bacteriocidal treatments.