Thiomicrospira denitrificans grows by gaining energy from the oxidation of reduced sulfur compounds such as hydrogen sulfide (H2S), thiosulfate ((S2O3)2-), or elemental sulfur (S), using oxygen or nitrate (NO3-) as electron acceptors. It uses CO2 as its carbon source. This organism would be classified as ______.

Following from the previous question about C. perfringens and gas gangrene, consider that this species lacks a TCA cycle and obtains ATP via fermentation. Knowing what you do about metabolism, what is the most likely explanation for how C. perfringens is able to maintain such a rapid doubling time while infecting a human host?

Following from the previous question, which of the following would best describe growth of C. jejuni?

Following from the previous question, C. jejuni is a chemoorganoheterotroph that relies on oxidative phosphorylation to generate ATP. Experiments have shown that under near-anaerobic conditions (1% or less oxygen), C. jejuni will migrate to 20 mM concentrations of dimethyl sulfoxide (DMSO), fumarate, nitrate, nitrite, and hydrogen peroxide, but will not do this when 6% or higher oxygen is present. Why would C. jejuni demonstrate this behavior?

Thiomicrospira denitrificans grows by gaining energy from the oxidation of reduced sulfur compounds such as hydrogen sulfide (H2S), thiosulfate ((S2O3)2-), or elemental sulfur (S), using oxygen or nitrate (NO3-) as electron acceptors. It uses CO2 as its carbon source. This organism would be classified as ______.

The agar deeps below were inoculated with unknown strains of bacteria which were added to agar that had been cooled to just above turning solid, mixed, and then poured into the test tubes. Following incubation, growth was observed as shown. Please match the label of each tube (i.e., A, B, C, D, or E) with the type of growth observed in the tube.

You inoculate a flask containing tryptic soy broth with a culture of E. coli and begin measuring the optical density of the culture with a spectrophotometer in order to detect growth. The measurements you take for the first few hours do not show any change, and then later in the day you begin to observe increases in numbers of cells (i.e., your absorbance readings increase). Which of the following best explains why there this delay in growth following inoculation?  

You perform a Gram stain on a sample of bacteria by following these steps on your dried smear of cells on a glass slide: Addition of a few drops crystal violet for 1 minute; rinse Addition of a few drops Gram’s iodine for 1 minute; rinse Decolorization with alcohol/acetone mixture until clear but fewer than 12 seconds; rinse Addition of a few drops of safrinin for 1 minute; rinse When finished, you observe a mixture of purple and pink cocci. Which of the following is the LEAST likely explanation for this outcome?

Following from the previous two questions, imagine you set up two cultures of T. denitrificans and measured the growth of each with a spectrophotometer. You provide both cultures with thiosulfate as an electron donor and sodium bicarbonate as the sole source of carbon. In culture A, you provide oxygen as a terminal electron acceptor. In culture B, you provide nitrate (NO3-) as a terminal electron acceptor. Which of the following would you predict best describes the growth of these two cultures?

Following from the previous question, researchers can grow T. denitrificans in lab using thiosulfate as an electron donor, nitrate as an electron acceptor, and sodium bicarbonate (NaHCO3-) as the sole source of carbon, which it incorporates using a reductive (reverse) TCA cycle. Under these conditions, T. denitrificans is growing ______ as a ______.