ch. 6 terms terminology

Question Answer
Psychophiles cold loving
Mesophiles moderate temperature loving
Thermophiles heat loving
Minimum growth temperature lowest temperature at which the species can grow.
Optimum growth temp Temperature which species will grow best.
Maximum growth temp highest temp possible for growth.
Psychotrophs encountered in low temp food spoilage grows well at fridge temps.
Acidophiles remarkably tolerant of acidity. ex: chemoautotrophic bacteria found in water drainage in coal mines has a pH value at 1.
Hypertonic when a microbial cell is in a solution whose concentration of solutes is higher than in the cell the cellular water passes out through the plasma membrane to the high solute concentration.
Plasmolysis osmotic loss of water causes shrinkage of the cells cytoplasm
extreme halophiles have adapted so well to high salt concentration that they actually require them for growth.
obligate halophiles have adapted so well to high salt concentration that they actually require them for growth.
facultative halophiles do NOT require high salt concentration but are able to grow at salt concentrations up to 2%, a concentration that inhibits the growth of many organisms.
carbon one of the most important requirements for microbial growth, it is the structural backbone of living matter; its needed for all the organic compounds that make up a living cell. Chemoautotrophs & photoautotrophs
nitrogen, sulfur, and phosphorous organisms primarily use nitrogen to form the amino group of the amino acid proteins. makes up about 14% of the dry weight of the bacterial cell. sulfur and phosphorous together make up another 4%.
nitrogen fixation use gaseous nitrogen N2 directly from the atmosphere. Organisms that use this are free living, mostly in the soil.
trace elements microbes require very small amounts of other mineral elements, such as iron, copper, molybdenum, & zinc. Most are essential for the functions of certain enzymes, usually as cofactors.
obligate aerobes organisms that require oxygen to live.
facultative anaerobes bacteria that have developed, or retained the ability to continue growing in the absence of oxygen.
obligate anaerobes bacteria that are unable to use molecular oxygen for energy-yielding reactions. In fact most are harmed or killed by it.
aerotolerant anaerobes cannot use oxygen for growth but they tolerate it fairly well.
microaerophiles require oxygen. Grow only in oxygen concentrations lower than those in air.
biofilms (slime) live in the isolated single-species colonies that we see on lab plates. Reside in a matrix made up primarily of polysaccharides, but also containing DNA and proteins often called slime.
culture medium nutrient material prepared for the growth of the microorganism.
inoculum microbes that are introduced into a culture medium to initiate growth.
culture microbes that grow and multiply in or on a culture medium.
agar when it is desirable to grow bacteria on a solid medium, a solidifying agent such as agar is added to the medium. A complex polysaccharide derived from marine alga, has long been used as a thickener in foods such as jellies and ice cream.
chemically defined medium one whose exact chemical composition is known.
complex media most heterotrophic bacteria and fungi such as you would work with in a lab are grown on this. Made up of nutrients including extracts from yeasts, meat, or plants, or digests of proteins from these and other sources.
nutrient broth soluble vitamins and minerals from the meats or yeasts are dissolved in the extracting water which is then evaporated so that these factors are concentrated. Particularly rich in vit. B and are in a liquid form.
nutrient agar not a nutrient.
reducing media anaerobes might be killed by exposure to oxygen, this special media is used.
selective media are designed to suppress the growth of unwanted bacteria and encourage the growth of the desired microbes.
differential media make it easier to distinguish colonies of the desired organism from other colonies growing on the same plate.
enrichment culture bacteria present in small numbers can be missed, especially if other bacteria are present in much larger numbers, it is sometimes necessary.
colony theoretically arises from a single spore or vegetative cell or from a group of the same microorganisms attached to one another in clumps or chains.
streak plate method the isolation method most commonly used to get pure cultures.
deep freezing process which a pure culture of microbes is placed in a suspending liquid and quick frozen.
lyophilization (freeze drying) suspension of microbes is quickly frozen at temperatures ranging from 54 to 72°C and the water is removed by a high vacuum.
binary fission refers to an increase in bacterial numbers, not an increase in the size of the individual cells. They usually reproduce by this.
budding species reproduce by this method. They form small initial outgrowth (a bud) that enlarges until its size approaches that of the parent cell and then it separates.
generation time the time required for the cell to divide and its population to double. Usually counts by 2's.
lag phase intense activity preparing for population growth, but no increase in population.
log phase logarithmic, or exponential, increase in population.
stationary phase period of equilibrium; microbial deaths balance production of new cells.
death phase population is decreasing at a logarithmic rate.
bacterial growth curve shows the growth of cells over time.
plate count the most frequently used method of measuring bacterial populations.
colony forming units colony often results, not from a single bacterium, but from short segments of a chain or from a bacterial clump.
serial dilution to ensure that some colony counts will be within this range the original inoculum is diluted several times.
pour plate method the nutrient medium in which the agar is kept liquid by holding it in a water bath at about 50°C is poured over the sample which is then mixed into the medium by gentle agitation of the plate.
spread plate method a 0.1 ml inoculum is added to the surface of a prepared, solidified agar medium. Inoculum is then spread uniformly over the surface of the medium with a specially shaped sterilized glass or metal rod.
filtration when the quantity of bacteria is very small, as in lakes or relatively pure streams, bacteria can be counted.
most probable number method estimated technique is based on the fact that the greater the number of bacteria in a sample, the more dilution is needed to reduce the density to the point at which no bacteria are left to grow in the tubes in a dilution series.

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