Devise a scheme to prepare a 10-9 dilution spread plate, using the least number of dilution tubes. Note: It is not practical to pipette any volume less than 0.1 ml and your equipment is similar to that in the Micro-lab, you only have 10 ml dilution tubes and a supply of sterile water

Answer the following questions briefly and concisely 1.How do bacteria in a chemostat and those in a batch culture vary from one another? 2.  What happens in a chemostat if the dilution rate is higher than the organism's maximum specific growth rate? 3.Does a chemostat require the use of pure cultures? 4. Why would a complicated culture media for Leuconostoc mesenteroides be simpler to make than one with a fixed chemical composition?

Your animal cell culture laboratory suddenly suffered from a bacterial contamination. Several components like vitamins, yeast hydrolysate, and fetal calf serum are temperature sensitive and must be filtered through a bacteriological filter to add to the autoclaved animal cell culture media. After careful considerations, you found that there are no issues with the autoclaving, but there is something wrong with the filter sterilization process, and changing new batches of filter did not remove the bacterial contamination. Which of the following rationale best describes the probable cause? Group of answer choices A. The media is probably contaminated with E. coli,  which passed through the 0.2-micron bacteriological filter. B. The media is probably contaminated with Mycoplasma, due to the lack of cell walls they are the only bacteria that can pass through the 0.2-micron bacteriological filter.   C. All of the other answer choices could be correct D. The media is probably…

At the station there is a 2 mL microcentrifuge tube containing sheep blood and 3 tubes containing the following solutions: 0 mM, 300 mM, 600 mM of sucrose. The tubes are randomly labelled A, B, C.  2 mL of each solution were transferred to a different microcentrifuge tube, 20 ul of blood were then added to each tube, and they were mixed well by inverting the tube for multiple times.  They were observed and it was determined whether the solution in each tube was hypotonic (Yes or No) relative to the blood cells. In addition, the solutions were diluted with water to help you determine which solution is which sucrose concentration. What sucrose concentration corresponds with each tube?   Tube Hypotonic (Yes/No) Hypotonic after 1:1 dilution with water (Yes/No) Most likely Sucrose concentration (mM) A No Yes   B Yes Yes   C No No

4. (a) Which of the following chemical reactions is an overall oxidation-reduction (redox) reaction that involves oxidation number changes in their reactions? A. NaOH + H₂O → Na¹ + H3O+ + OH B. HCl + H₂O → H3O+ + Cl- C. CO₂ + H₂O → H+ + CO3²- D. N₂ + 3H₂ → 2NH3

You are determining the concentration of your culture, and have counted the following on your hemocytometer as shown in Figure below: (note, blue cells have taken up Trypan blue & thus are dead. Red x's are cells that should not be counted because touching one of 2 sides of square). If your cells were diluted 1:2 before counting, what is the concentration of cells in your original culture?

Develop an equation for calculation of pressure as a function of the number of passes through the homogenizer. What factor(s) did you take into consideration when selecting the number of passes? Escherichia coli cells are lysed with the same homogenization, is this organism gram-positive or gram-negative? What impact does increasing the value of the constant, a, have on the required number of passes at a given pressure? What factors impact the value of a? If fine cell debris after homogenization makes subsequent solid-liquid separation difficult, what would you recommend?

4) You are interested in the total bacterial load of the bat guano. In order to determine this, you go back to your original broth culture and prepare a dilution series. You then spread 100 ml of each dilution onto 3 separate plates. You obtain the following results:   Plate 1, 10 -1 dilution: 362 colonies Plate 2, 10 -3 dilution:  76 colonies Plate 3, 10 -5 dilution:   8 colonies.   Based on your results, calculate the CFUs/ml in your original broth culture. show your work

Develop a spreadsheet to predict as functions of time with concentration, volimme and permeate flows for a batch ultrafiltration. Assume that the flux depends on concentration as follows: J(L/M²/H) = A*EXP(-bC) where C is the retentate concentration in g/l. Assume that the recirculation rate is kept high enough that shear rate dependence is eliminated. Do a sample run with C.= 0.5 g/l, Cfinal = 50 g/l, A = 50, and b = 0.02. Assume a filtration area of 19.4M² and an initial volume of 3255 L. Assume σ (protein) = 1.0 or σ (protein) = 0.95 or σ (protein) = 0.90.

How would you produce a 10^-1 dilution if a 3 mL bacterial sample using the entire 3 mL volume?  suppose your professor handed you a test tube with 2.0 mL of an E. coli broth culture in it and told you to make a 10^-1 dilution of the entire culture. Explain how you would do this. Show your calculations.