microbial growth lab

atmospheric gases, nutrients, pH energy sources, and radiation are all examples of ___ factors that affect microbial growth

environmental

the slowed growth or lack of growth of an organism at temperatures of pH outside of its ideal range is most likely due to changes in its

enzymes

a tube of fluid thioglycollate medium is inoculated with a bacterial isolate. after incubation the bacteria appear to be growing throughout the tube. this bacterial isolate is most likely an

facultative anaerobe

based on this FTM tube result, how would you classify this organism

facultative anaerobe

which of the following organisms is most flexible with regard to its oxygen requirements

facultative anaerobe

all microorganisms use oxygen in their metabolism

false

bacteria classified as ___ would thrive in the great salt lake

halophiles

halobacterium salinarium will only grow at high salt concentrations, generally 15% to 30% NaCl. which term below describes this environmental preference

halophilic

the organisms indicated by the arrow would be classified as ___ organisms

halophilic

an alkalinophile is a microorganism that prefers a growth environment that

has a pH>8.5

which of the following are toxic by-products formed in the presence of oxygen

hydroxyl radical superoxide ion peroxide

microorganisms growing on mucous membranes such as the oral mucosa or vaginal mucosa are most likely in a ___ environment

isotonic

which term would describe the tonicity of an environment in which the solute concentration is the same as that of the interior of the microbial cells

isotonic

microorganisms whose optimal growth temperature is 37C are classified as

mesophiles

most human pathogens are classified as

mesophiles

a solution with a pH of 7 is

neutral

if an organism grows in the anaerobe jar but not under normal atmospheric oxygen levels, it would be classifies as a

obligate anaerobe

the fastest growth rate of a microorganism occurs at its ___ temperature

optimum

the activated chemical pack that is added to an anaerobe jar effectively removes

oxygen

which of the following are environmental factors that affect microbial growth

pH, nutrients, temperature, osmotic pressure, atmospheric gases

the pink color in a tube of fluid thioglycollate medium (FTM) indicate

presence

which of the following are most likely to be affected by pH changes

proteins

which classifications of organisms can be a concern for growth in refrigerated foods

psychrophiles psychrotrophs

which of these laboratory items are usually used to inhibit the growth of most types of microorganisms by alterig their environment

salt plates, refrigerator

human skin provides an environment with NaCl levels slightly above that of most bacterial cells. which organism would most likely be found on the skin

staphylococcus aureus; a halotolerant organism

a microorganism is classified as a psychrophile, a mesophile, or a thermophile based on its optimum growth

temperature

what is your hypothesis

the organism will grow within a range of temperatures

which of the following environmental conditions are preferred by a majority of organisms

warm temperatures, neutral pH, isotonic environments

choose the answer that represents the ideal environment for a majority of microbes

warm, isotonic, neutral pH

match the solution description with the direction of water movement when cells are placed into each solution

- hypotonic solution = a net movement of water into the cells will occur - isotonic solution = there will be no net movement of water either into or out of the cells - hypertonic solution = there will be a net movement of water out of the cells

which of the following may occur at temperatures below a microorganism's minimum growth temperature

- membrane transport may be disrupted - slowing of metabolic activity - decreased fluidity of the plasma membrane

which of the following are used to describe the range of temperature over which a microbe will grow

- minimum growth temperature - optimum growth temperature - maximum growth temperature

which organisms should be able to grow in the anaerobe jar

- obligate anaerobe - facultative anaerobe

determine the correct oxygen requirement classification for each of the organisms seen in this image

- organism at #1 = facultative anaerobe - organism at #2 = obligate aerobe - neither organism #1 or #2 would be classified as this type = obligate anaerobe

which of the following organisms are expected to grow within an anaerobe jar

- facultative anaerobes - obligate anaerobes - aerotolerant anaerobes

you inoculate a plate with two different organisms and incubate in an anaerobic jar for 24 hours. this is the result you see after incubation. which of the following are possible conclusions regarding these organisms

- they may be obligate anaerobes - they cannot be obligate aerobes - they can grow in the absence of oxygen - they may be facultative anaerobes, but that cannot be determined from theses results alone

rank the following, from the highest growth temperature range (at the top) to the lowest growth temperature range (at the bottom)

1. extreme thermophile 2. thermophile 3. mesophile 4. psychrotroph 5. psychrophile

match the oxygen requirement classification with the correct description of the expected FTM tube result

1. facultative anaerobe = growth throughout the tube 2. obligate anaerobe = growth towards the bottom of the tube 3. obligate aerobe = growth towards the top of the tube

to promote the development of red pigmented colonies by serratia marcescens, cultures should be incubated at

25 C

which of the following would be used to provide the optimum growth temperature for microorganisms that typically grow in humans

37 C incubator

which statement correctly describes the growth of an organism across the pH scale

a microorganism will grow across the range of pH that allows for normal enzymatic function

which statement best describes the growth patterns of microorganisms based on their temperature preferences

a microorganism will grow across the range of temperatures tolerated by its enzymes

in an anaerobe jar, oxygen is

absent

the lower the pH, the more ___ the environment

acidic

match the descriptive term with the optimal pH for growth

acidophile = pH<5.5 neutrophile = pH = 7 alkalinophile = pH>8.5

identify the types of laboratory items that can be used to enhance growth of most commonly encountered microbes

anaerobe jar, incubator, isotonic culture media

if comparing growth of a microbe in broth tubes incubated at different temperatures, the tube incubated at the organism's optimum temperature would

be the most turbid (cloudy)

the change or breakdown of three dimensional protein structure that may result from a pH outside of an organism's growth range is referred to as

denaturation

temperature above the maximum growth temperature for a microorganism are likely to result in

denaturation of enzymes