1. A microbial cell that normally carries out aerobic respiration has encountered an environment of low oxygen and may die if the levels do not increase.
a. Describe the key role that oxygen plays for this microorganism in the aerobic respiration process and what will occur differently without oxygen that could lead to cell death.
b. How would you class this organism in terms of oxygen for growth requirements?
1. A microbial cell that normally carries out aerobic respiration has encountered an environment of low oxygen and may die if the levels do not increase.
a. Describe the key role that oxygen plays for this microorganism in the aerobic respiration process and what will occur differently without oxygen that could lead to cell death.
b. How would you class this organism in terms of oxygen for growth requirements?
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The Case of the Paralyzed Gardener. Part 2.
Katie, Julia's girlfriend, was really scared now. In addition to having trouble opening her eyes and slurring her words, Julia could now hardly walk or sit up. Katie called an ambulance, and they rushed Julia to the hospital. Due to the sudden onset and the neurological nature of the signs and symptoms, the doctor tested Julia for a stroke.
Fortunately, the results came back negative. Since Julia could not speak, the doctor began asking Katie questions about her partner's health, habits, and lifestyle. Eventually, it came up that Julia frequented farmers markets and had recently consumed some vegetables she canned at home. Upon hearing about the home canning, the doctor immediately suspected botulism. Clostridium botulinum bacteria are common in soil, so they can easily contaminate vegetables, and improper canning is a known risk factor for exposure. Although the doctor knew that the collected blood and stool samples may contain the bacterium and/or the botulinum toxin, the results would take several days to obtain, and Julia didn't have days to wait. Based on mounting suspicion, the doctor ordered an electromyography study, which confirmed that Julia's muscles and nerves were not working properly. Because botulism is a nationally reportable disease, the physician immediately contacted the local health department and, in collaboration with the U.S. Centers for Disease Control and Prevention, coordinated delivery of the antitoxin that was needed to save Julia's life.
Several days later, the lab confirmed that botulinum toxin was found in Julia's blood samples and, C. botulinum was grown from stool samples. It was a good thing the doctor had reacted so swiftly to obtain the antitoxin. Though the doctor had identified the cause of the illness, the source of the bacteria was still not confirmed. Was it food from the market? Her canned goods? Somewhere else? When placed in a stressful environment like soil, this bacterium sporulates, forming hardy structures called endospores that can survive for decades. The low oxygen and low acid environment that occurs in certain canned vegetables can allow the endospores to germinate, leading to toxin production.
Since Julia was new to canning, Katie suspected that it was the beans and corn. She mentioned this point to the doctor, who requested a can of each to send to the health department for confirmation. At the lab, the technicians did some basic staining and growth to see if there was bacterial contamination. Though the identification was not definitive, they were able to grow Gram-positive bacilli from Julia's canned food.
QUESTION 1: The process of canning vegetables involves high heat and, sometimes, low pH to kill contaminating microorganisms. How do you think these might prevent bacterial growth? Select all that apply. (NCLEX style)
| A.Degrading sugars used as microbial food sources | ||||
| B. Denaturing proteins | ||||
| C. Altering quaternary structures | ||||
| D. Destroying cell membranes QUESTION 2: When an animal's gastrointestinal tract is colonized with C. botulinum, the causative agent of botulism, the bacteria secretes a neurotoxin, which moves into the bloodstream and down its concentration gradient without help from any external energy or proteins. Which of the following terms correctly describes this sort of molecular movement?
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