During which growth phase will gram negative bacteria be most susceptible to penicillin?
|Term In figure 6.1 which line best depicts the growth of a facultative anaerobe in the absence of O2?||Definition B|
|Term During which growth phase will gram-positive bacteria be most susceptible to penicillin?||Definition Log phase|
|Term In figure 6.4 in which tube are microaerobes growing?||Definition E.|
Which of the following is an advantage of standard plate count?
The correct answer: An advantage of the standard plate count is that it e. Determines the number of viable cells.
Which of the following is an advantage of the direct microscopic count?
Direct Microscopic Count A major advantage of direct counts is the speed at which results are obtained. However, since it is often not possible to distinguish living from dead Page 3 35 cells, the direct microscopic count method is not very useful for determining the number of viable cells in a culture.
What is direct microscopic count?
Direct counting methods include microscopic counts using a hemocytometer or a counting chamber. The hemocytometer works by creating a volumetric grid divided into differently sized cubes for accurately counting the number of particles in a cube and calculating the concentration of the entire sample.
What pH do most bacteria grow best in?
6.5 – 7.0
What level of moisture does bacteria grow well in?
Safety & Sanitation – chapter 2A
|bacteria grows well in food with high levels of moisture. this is called ____||water activity (aw = a with subscript w)|
|the scale of water activity is||0.0 to 1.0|
|food with a water activity of _____ or higher is ideal for bacterial growth||0.85|
Does bacteria grow faster in high humidity?
Studies have indicated that the growth of microorganisms, such as fungus and bacteria, completely cease when temperatures reach < -18°C/0°F. Thus, decreasing temperature and moisture (relative humidity), creates a less hospitable environment for microorganisms to grow.
What are the six condition in which bacteria can sustain growth?
FAT TOM is a mnemonic device used in the food service industry to describe the six favorable conditions required for the growth of foodborne pathogens. It is an acronym for food, acidity, time, temperature, oxygen and moisture.
Do Germs thrive in heat?
Bacteria can live in hotter and colder temperatures than humans, but they do best in a warm, moist, protein-rich environment that is pH neutral or low acid. There are exceptions: some bacteria thrive in extreme heat or cold. some can survive under highly acidic or extremely salty conditions.
Which food allows bacteria to grow well?
TCS food, like dairy products, eggs, meat, and poultry support the growth of bacteria, hence ideal for bacterial growth. Other TCS food items are milk, shellfish, crustaceans, baked potatoes, sprouts, sliced melons, cut leafy vegetables, tofu, and fish.
What causes bacterial growth?
Environmental conditions. Environmental factors influence rate of bacterial growth such as acidity (pH), temperature, water activity, macro and micro nutrients, oxygen levels, and toxins. Conditions tend to be relatively consistent between bacteria with the exception of extremophiles.
What factors affect the growth of bacteria in general?
Some of the important factors affecting bacterial growth are:
- Nutrition concentration.
- Gaseous concentration.
- Ions and salt concentration.
- Available water.
Where does bacteria like to grow?
Bacteria can live in hotter and colder temperatures than humans, but they do best in a warm, moist, protein-rich environment that is pH neutral or slightly acidic. There are exceptions, however. Some bacteria thrive in extreme heat or cold, while others can survive under highly acidic or extremely salty conditions.
What is the growth rate of bacteria?
Generation times for bacteria vary from about 12 minutes to 24 hours or more. The generation time for E. coli in the laboratory is 15-20 minutes, but in the intestinal tract, the coliform’s generation time is estimated to be 12-24 hours.
What temperature is the best for bacterial growth?
Information. Bacteria grow most rapidly in the range of temperatures between 40 °F and 140 °F, doubling in number in as little as 20 minutes.
How many bacteria are produced in 4 hours?
What is mean generation time?
Generation time is the average interval between the birth of an individual and the birth of its offspring. To determine the mean generation time of a population, the age of the individuals (x) is multiplied by the proportion of females surviving to…
How do bacteria respond to stimuli?
When exposed to osmotic stress from the environment, bacteria act to maintain cell turgor and hydration by responding both on the level of gene transcription and protein activity. Upon a sudden decrease in external osmolality, internal solutes are released by the action of membrane embedded mechanosensitive channels.
Do viruses respond to stimulus?
Viruses – The Boundary of Life They do not respond to stimuli, they do not grow, they do not do any of the things we normally associate with life. Strictly speaking, they should not be considered as “living” organisms at all.
Does algae can sense and respond to stimuli?
Algae aren’t very responsive to any stimulus besides light. The only way I ever got algae I worked with to respond to any sort of stimulus was to hit them with an intense burst of light, which caused them to visibly move and for their chloroplasts to change position within the cell.