For effect of temperature on microbial growth exercise 28, what results would you be looking for? what are indicators?Effect of Physical and Chemical Environmental Factors on Microbial Growth Bacteria and other miciobes hove limined control over theirmsemslemironments. Whereas many eukaryotes have evoived woghisticated intemal control mechanisms, micobees ate alnot completely dependent on externil factos to provide condations suinable for their eibtence Ningrenironmenol changes can dramatically change a microorganisms ability to tranaport materials a coss the membrone, perf fom complex entymatic rextions, and maintain critical cytoplasmic pressure. One way to observe microbiat responses to emvironmenteal changes is to art incilly macipulate an edemal factor and measure its effect on growh rite, thatis cell density atter a given incubation time In this seties of laboratory eeercises you will eamine the effects of temperature, pH, and osmotic pressure on growth eate. When appropriate you wil antempt 10 classily organians based on your results The Effect of Temperature on Microbial Growth Theory Bacteria and Archaca have been divcovered living in above 80 C. Figure 2.41 illustrates typical temperature habitats ranging from 10C to more than 110C. ranges and classifitations of Bacteria and Archaca. The temperature range of any single specic, howeves, is a small portion of this overall range. As such, each species is chancterized by a minimum, maximum, and optimum temperature-collectively known as its cardinal temperatures (Fig. 2.40). Minimum and maximum temperarures are, simply, the temperatures below and above which the organism will not survive. Optimum temperature is the temperature at which an organism grows the fastest-its highest growth rate. Organisms that only grow below 20C are called psychrophiles. These are common in ocean, Arctic, and Antarctic habitats where the temperature remains permanently cold with little or no fluctuation. Organisms adapted to cold habitats that fluctuate from about 0C 2.40 Typical Growth Range of a Mesophile a The Trinimum? to above 30C are called psychrotropts. Bacteria and "maxiticn' yesur peratures be, ond which no growtitakes pl: adapted to temperatures between 15C and 45C are known as mesophiles. Most bacterial residents in the human body, as well as numeroos human pathogens, are mesophiles. Thermophiles are organisms adapted to temperatures above 40C. Thermophiles that will not grow at temperarures below 40C are called obligate thermophiles; those that will grow below 40C are known as facultative thermophiles. Environments in which thermophilic Bacteria and Archaea are found include composting organic material, soil surfaces subjected to direct sumlight, and silage. Bacteria and Archaca isolated from ocean floor hydrothermal vents and other geothermal sites (Fig. 2.1) 2.41 Thermal Classifications of aacteria = These are gened are called extreme thermophiles because they can survive cardinal temperature g.

1. For effect of temperature on microbial growth exercise 28, what results would you be looking for?
what are indicators?Effect of Physical and Chemical Environmental Factors on Microbial Growth
Bacteria and other miciobes hove limined control over theirmsemslemironments. Whereas many
eukaryotes have evoived woghisticated intemal control mechanisms, micobees ate alnot
completely dependent on externil factos to provide condations suinable for their eibtence
Ningrenironmenol changes can dramatically change a microorganisms ability to tranaport
materials a coss the membrone, perf fom complex entymatic rextions, and maintain critical
cytoplasmic pressure. One way to observe microbiat responses to emvironmenteal changes is to
art incilly macipulate an edemal factor and measure its effect on growh rite, thatis cell density atter
a given incubation time In this seties of laboratory eeercises you will eamine the effects of
temperature, pH, and osmotic pressure on growth eate. When appropriate you wil antempt 10
classily organians based on your results The Effect of Temperature on Microbial Growth Theory
Bacteria and Archaca have been divcovered living in above 80 C. Figure 2.41 illustrates typical
temperature habitats ranging from 10C to more than 110C. ranges and classifitations of Bacteria
and Archaca. The temperature range of any single specic, howeves, is a small portion of this
overall range. As such, each species is chancterized by a minimum, maximum, and optimum
temperature-collectively known as its cardinal temperatures (Fig. 2.40). Minimum and maximum
temperarures are, simply, the temperatures below and above which the organism will not survive.
Optimum temperature is the temperature at which an organism grows the fastest-its highest
growth rate. Organisms that only grow below 20C are called psychrophiles. These are common in
ocean, Arctic, and Antarctic habitats where the temperature remains permanently cold with little or
no fluctuation. Organisms adapted to cold habitats that fluctuate from about 0C 2.40 Typical
Growth Range of a Mesophile a The Trinimum? to above 30C are called psychrotropts. Bacteria
and "maxiticn' yesur peratures be, ond which no growtitakes pl: adapted to temperatures between
15C and 45C are known as mesophiles. Most bacterial residents in the human body, as well as
numeroos human pathogens, are mesophiles. Thermophiles are organisms adapted to
temperatures above 40C. Thermophiles that will not grow at temperarures below 40C are called
obligate thermophiles; those that will grow below 40C are known as facultative thermophiles.
Environments in which thermophilic Bacteria and Archaea are found include composting organic
material, soil surfaces subjected to direct sumlight, and silage. Bacteria and Archaca isolated from
ocean floor hydrothermal vents and other geothermal sites (Fig. 2.1) 2.41 Thermal Classifications
of aacteria = These are gened are called extreme thermophiles because they can survive cardinal
temperature graphs for exch ategory and repesert aco temperatures in the 65C and 110C range
(op to 122C ite of al the individual graphs foreach spedes Feler to the tekt fol for Methanopyrus).
Extreme thermophiles grow bect.1 Clean the outside of all tubes with a tissue, and place them in a
test tube rack organized into groups 5 Using the data from the Broth Data table, circle the by
organism. estimated cardinal remperarures of each of the four 2 Mix each broth gently until
uniform turbidity is organisms. Then, based on your results, classify each organism. achieved. Be
careful not to splash into the caps. 3 Compare all tubes of a species to each other. Rare 6 On the
graph paper provided with the data sheet, plot the relative turbidity values versus temperature for
the each as 0,1,2, or 3 , according to irs turbidity 0 is four organisms, If you need help with
graphing, see clear-the uninoculated tube-and 3 is highly turbid pages 1011. and is established by

2. the most turbid tube out of the 20). Record these in the Broth Data table on the dara 7 Dispose of
both plates and all tubes in their sheet, page 109. appropriate autoclave containers when finished.
4 Examine the Sernatia marcescens plates incubated at two different temperafures, compare the
growth characteristics, and enter your results in the Plate Data table on the data sheet.