Helicobacter pylori, a bacterium that causes stomach ulcers, can grow in medium with a pH above 5.  It can survive but not grow in pH 2 medium as long as the medium contains Urea.  You inoculate a pH 2 broth with 1,000,000 H. pylori and for 8 hours the organism did not grow.  The next morning however, the medium has become quite turbid, suggesting that the organism has grown.  Explain how this could happen. What phylum and class does this organism belong?

10 mL of a culture of Enterobacter at 104 cells/mL is introduced into 990 mL of the same broth at the same temperature (37° C) with adequate mixing. It is 8 p.m. the night before class on Tuesday at 11 a.m. Doubling time for this species is 40 minutes. Will the culture reach Stationary Phase before  class? What time the culture does reach Stationary Phase?

A new intestinal isolate of E. coli is known to have a generation time of 12 minutes. If a culture contained 3, 221,225,472 bacterial cells after 6 hrs how many bacteria must have been inoculated into the culture at time 0.

A lab interested in isolating Escherichia coli from food samples uses a lot of Eosin Methylene Blue (EMB) Agar. The recipe for this media is 36 g/L deionized water. How many grams of media would be required to prepare 350 plates assuming 20 mL per plate? 072 O 112 O 90 O 252

Suppose you observed a bacterium growing on Mannitol Salt agar (MSA) with a yellow colony appearance in the clinical microbiology lab. Name the genus and species you are most likely observing; state its most likely oxygen needs and salt requirements; and predict if this organism would grow on MacConkey agar or Colistin Nalidixic Acid agar. If you want to control the growth of this organism in a healthcare setting, predict what disinfectants would be best to use and their modes of action. Explain your reasoning

Staphylococcus aureus is non-motile, a facultative anaerobe, and a mesophile. At 37⁰C in abundant glucose, which incubation environment is more likely to produce the highest cell mass of S. aureus within two hours? Flask with aeration to add oxygen to the broth and shaking Flask left on the lab bench Flask grown in an anaerobic chamber that removes oxygen from the air around the flask Flask without aeration All will be equal

A bacterial organism is catalase positive and cytochrome oxidase positive. This could suggest that the organism is an obligate aerobe. True or false?

Which of the following groups of bacteria require or will use oxygen for respiration i. obligate aerobes ii. facultative anaerobes iii. obligate anaerobes iv. microaerophile v. aerotolerant anaerobe i & iv ii. & iv Oi&ii i, ii, iv ii & iv

Which of the following prevented an aerotolerant anaerobic, mesophilic and halophilic bacterium from contaminating your home aquarium? the water was at 37ºC you placed a high amount of glucose into the aquarium you placed several pennies in the aquarium you were using a .45 um filtering unit you placed carbon dioxide instead of oxygen into the aquarium

Flasks A and B contain broth, and are inoculated with an identical number of bacteria that are facultative anaerobes. Flask A contains a triglyceride lipid as the sole nutrient source, and Flask B contains a monosaccharide called fructose as the sole nutrient source. Both flasks are incubated at 30°C with aeration (oxygen is added to the broth). Assume the bacteria are capable of catabolism of both fructose and triglycerides. Mark all the correct statements pertaining to these cultures. A. Under anaerobic conditions, cells in flask A will produce more ATP B. Cells from flask B will produce more carbon dioxide C. Cells from flask B will produce more ATP D. Flask A will have the greater cell mass E. Cells from flask A will produce more ATP F. Cells from flask A will produce more carbon dioxide G. Flask B will have the greater cell mass H. Under anaerobic conditions, cells in flask B will produce more ATP