Microbial Growth Part 3

bacteria growth best in a higher concentration of CO2 and a lower concentration of O2 than present in the atmosphere:

capnophiles

common approach to grow capnophiles:

candle jar

most favorable pH for the growth of an organism:

optimum growth pH

lowest pH that an organism can tolerate:

minimum growth pH

most bacteria are ____, meaning they grow optimally at a pH within one or two pH units of the neutral pH of 7.

neutrophiles

most strains of e. coli and salmonella sp. are ____.

neutrophiles

have optimum pH ranges below pH 5.5:

acidophiles

suldolobus sp. are extreme ____.

acidophiles

lactobacillus bacteria are ____ that live in the genitourinary tract.

acidophiles

increased negative surface charge of proteins:

acidophiles

pumps to actively eject H+ ions out of the cells:

acidophiles

changes in phospholipid composition to maintain membrane fluidity at low pH:

acidophiles

grow best at pH between 8.0 and 11:

alkaphiles

pathogenic agent of cholera vibrio cholerae example of ____.

alkaphiles

modification of lipid and protein structure:

alkaphiles

mechanisms to maintain the proton motive force in an alkaline environment (or use Na+ gradients instead):

alkaphiles

enzymes with higher isoelectric points due to incorporating more basic amino acids:

alkaphiles

lowest temperature at which an organism can survive and replicate:

minimum growth temperature

highest temperature at which growth can occur:

maximum growth temperature

middle loving organisms that grow in moderate temperatures:

mesophiles

optimal growth temperatures range from room temperature (about 20°C) to about 45°C:

mesophiles

human body core temp is 37°C so human microbiota organisms and pathogens are ____.

mesophiles

also known as psychrotolerant and prefers cooler environments:

psychrotrophs

optimal growth temperatures range from 4°C (refrigerator temp.) to 25°C:

psychrotrophs

found in temperature climates and are responsible for the spoilage of refrigerated food:

psychrotrophs

(cold loving) organisms can grow in temperatures below freezing:

psychrophiles

optimal growth temperatures range from -20°C to 20°:

psychrophiles

found in permanently cold environments such as the earth’s poles and deep waters of the oceans:

psychrophiles

list the 2 important decomposers in cold climates:

psychrotrophs; psychrophiles

proteins are rich in hydrophobic residues and display an increase in flexibility compared with homologous proteins:

psychrophiles

antifreeze proteins and solutes decrease the freezing temperature of the cytoplasm:

psychrophiles

membrane lipids are unsaturated to increase fluidity:

psychrophiles

growth rates are much slower than those encountered at moderate temperatures:

psychrophiles

grow at optimum temperatures between 50°C and 80°C:

thermophiles

do not multiply at room temperature:

thermophiles

found in hot springs, geothermal soils, and manmade environments such as garden compost piles:

thermophiles

grow at optimum temperatures 80°C and 110°C:

hyperthermophiles

found in hydrothermal vents:

hyperthermophiles

can survive autoclaving (121°C):

hyperthermophiles

high ratio of saturated lipids limits the fluidity of the cell membranes:

thermophiles

more G-C base pairs in DNA (3 H-bonds v. 2 H-bonds at A-T base pairs):

thermophiles

additional ionic and covalent bonds in protein secondary structures to stabilize folding and resist denaturation:

thermophiles

rigid cell walls protect the cells from bursting in a dilute ____ environment and do not have much protection against high osmotic pressure:

hypotonic

cells in ____ environment water flows out of the cell, leading to plasmolysis and cell death.

hypertonic

salt tolerant organisms that can survive and divide in the presence of high salt:

halotolerant

salt-loving organisms that require high salt concentrations to grow:

halophiles

countering high osmotic pressure with a high cytoplasmic concentration of glycerol:

halophiles

actively pumping out salt ions:

halophiles

accumulating large concentrations of K+ and other ions in the cytoplasm:

halophiles

changes in protein structure to function at high salt concentrations:

halophiles

media that can grow a variety of organisms:

general purpose

media that contains added nutrients to promote the growth of fastidious organisms:

enriched

organisms that cannot make certain nutrients and require them to be added to the medium:

fastidious

media in which the exact chemical composition is known:

chemically defined

media that contains extracts and digests of yeasts, meats, or plants so precise chemical composition is not known:

complex

media where amounts of individual components are undetermined and variable:

complex

blood agar, tryptic soy, and brain heart infusion media are examples:

complex

media supports the growth of all microorganisms without any specific inhibition:

non-selective

used to cultivate organisms for downstream applications or for specific procedures:

non-selective

mueller-hinton is a ____ medium used for antibiotic testing as it contains starch to stabilize antibiotic function and has a lower agar percentage to allow antibiotic diffusion.

non-selective

media that inhibits the growth of specific organisms while supporting the growth of others:

selective

compounds like antibiotics, dyes, or salts are added to prevent the growth of certain organisms:

selective

other compounds like vitamins are added to encourage the growth of other organisms:

selective

mannitol salt agar is a ____ medium that contains 7.5% NaCl that inhibits the growth of most organisms but permits the growth of halotolerant bacteria like staphylococcus.

selective

media that can distinguish colonies of different bacteria by a change in the color of the colonies or the color of the medium:

differential

color changes result from the interaction of bacterial enzymes with substrates in the medium:

differential

in cases of blood agar, color changes occur due to damage of red blood cells by bacterial enzymes or toxins:

differential

MacConkey is an example of _____ medium due to fermentation of lactose in the medium leading to the production of organic acids, causing pH to lower, leading to color change in the indicator dye neutral red.

differential

selective and differential media can be combined and play an important role in the ID of bacteria by biochemical methods. true or false?

true