Chapter 3: Microbial Growth Flashcards
(111 cards)
1
Q
physical requirements
A
temperature, pH, osmotic pressure
2
Q
chemical requirements
A
carbon, nitrogen, sulfur, phosphorous, oxygen, trace elements, organic growth factors
3
Q
psychrophiles
A
cold loving
4
Q
psychrotrophs
A
grow betweeen o and 20-30 degrees C
cause food spoilage
5
Q
mesophiles
A
moderate temperature loving
6
Q
thermophiles
A
heat loving, optimum growth 50-60 degrees C
7
Q
hyperthermophiles
A
optimum growth above 80 degrees C
hydrothermal vents
8
Q
most bacteria grow between pH of
A
6.5 and 7.5
9
Q
molds and yeasts grow between pH of
A
5 and 6
10
Q
acidophiles grow in pH of
A
acid pH
11
Q
hypertonic environment
A
more solute outside cells
12
Q
plasmolysis
A
cell shrinking due to high osmotic pressure
13
Q
extreme/obligate halophiles require high
A
osmotic pressure (high salt)
14
Q
facultative halophiles tolerate
A
high osmotic pressure
15
Q
why is carbon required
A
backbone of organic molecule
16
Q
why is nitrogen required
A
component of proteins, DNA, RNA, ATP
17
Q
why is sulfur required
A
in amino acids, thiamine, biotin
18
Q
why is phosphorous required
A
used in DNA, RNA, ATP; found in cell mambranes
19
Q
why are trace elements required
A
inorganic elements required in small amounts usually as enzyme cofactors
20
Q
what trace elements are needed
A
iron, copper, molybdenum, zinc
21
Q
obligate aerobes
A
need oxygen
22
Q
facultative anaerobes
A
grow via fermentation or anaerobic respiration without oxygen
23
Q
obligate aerobes
A
unable to use oxygen and harmed by it
24
Q
aerotolerant anaerobes
A
tolerate but cannot use oxygen
25
microaerophiles
require oxygen concentration lower than air (21%)
26
bacteria from lowest to highest in terms of oxygen
obligate aerobes, aerotolerant annaerobes, microaerophiles, facultative anaerobes, obligate anaerobes
27
organic growth factors
organic compounds obtained from environment
28
types of organic growth factors
vitamins, amino acids, purines, pyrimidines (vitamins are inorganic)
29
biofilms
microbial communities that form slime of hydrogels that adhere to surfaces
30
bacteria communicate cell to cell via
quorum sensing
31
benefits to biofilms
share nutrients to increase growth and reproduction, shelter bacteria from harmful environment, 1000x resistance to microbicide
32
culture medium
nutrients prepared for microbial growth, most common is agar
33
sterile
no living microbes
34
inoculum
introduction of microbes into a medium using sterile pipet, loop, or swab
35
culture
microbes growing in or on a culture medium
36
agar
complex polysaccharide used as solidifying agent for culture media for petri plates
37
chemically defined media
exact chemical composition is known used to grow fastidious organisms which require many growth factors
38
complex media
extracts and digests of yeasts, meats, and plants, chemical composition varies batch to batch
39
difference betweeen nutrient broth and nutrient agar
broth is liquid, agar is solid
40
reducing media
used for cultivation of anerobic bacteria
41
reducing media contains
sodium thioglycolate that combine O2 to deplete it - heated to drive oxygen off
42
capnophiles
microbes require high CO2 conditions; create CO2 packet using candle jar
43
BSL 1
no special precuations, basic teaching lab
44
BSL 2
lab coat, gloves, eye protection
45
BSL 3
biosafety cabinets to prevent airborne transmission
46
BSL 4
seals, negativee pressure, hot zone - fully suited, air tube filtered through HEPA filters
47
what is special about HEPA filters
can filter viral particles
48
selective media
contains inhibitors to suppress unwanted microbes to grow pure cultures
49
differential media
allows distinguishing of colonies of different microbes on same plate
50
enrichment culture
encourages growth of desired microbe by increasing very small numers of desired organism to detectable levels - usually a liquid
51
pure culture
contains one speciess or strain
52
colony
10-100 million cells arising from a single cell
53
CFU
colony forming unnit
54
streak plate method
used to isolate pure cultures
55
deep-freezing
-50 to -95 degrees C to preserve microbes
56
lyophilization (freeze drying)
-54 to -72 degrees C and dehydrated in a vacuum to preserve microbes
57
bacterial growth
increase in number of cells, NOT cell size
58
binary fission
one splits into two; cell elongates, DNA replicates, cell wall/membrane constrict, cross-wall forms, cell separates
59
other methods of microbial reproduction
budding, conidiospores (actinomycetes - fungus), fragmentation of filaments
60
exponential growth
2 ^(# of generations) growth curves represented logarithmically
61
phases of microbial growth graph
lag, log, stationary, death
62
lag phase
no significant increase in population growth
63
log phase
exponential growth
64
stationary
reproduction equals death
65
death phase
population decreases
66
population dynamics important to study
infectious disease, food preservation, industrial processes (ethanol)
67
direct measurements
plate fount, filtration, most probable number, direct microscopic count
68
plate count
count colonies, original inoculum must go through serial dilution
69
plate counts occur on
agar via pour plate mehtod or spread plate method
70
filtration
solution passses through filter that collects bacteria; placed on petri dish and allowed to grow
71
most probablt number
multiple tube test, count positive tubes, compare to statisticle table
5 tubes per set, 3 sets, dilutions of 10mL, 1mL, and 0.1mL
72
direct microscopic count
volume of bacterial suspension placed on slide, acerage # of bacteria per viewing field calculated
73
direct microscopic count uses what type of cell counter
Petroff-Hausser
74
numer bacter/mL =
cells counted / volume area counted
75
turbidity
measuring cloudiness with spectrophotometer
76
metabolic activity and turbiditiy
amount of metabolic product is proportional to # of bacteria
77
dry weight
bacteria are filtered, dried, and weight - used for filamentous organisms
78
antibiotic resistance forces us to
change way we view disease and treat patients
79
evolution of resistance
mutation
80
mechanisms of resistance
conjugation, transductions, transformation
81
development of resistant population
resistant cells are not killed off, continue to divide resulting in completely resistant population
82
mutation and evolutionary pressure cause
rapid increase resistance to antibiotics
83
how does modern technology/sociology relate to resistance
travelers carry resistant bacteria, spreads quickly
| large cities with poor sanitation
84
how is food a source of infection that can develop resistance
food prepared outside of home; contamination unnoticed until outbreak occurs - hard to trace origin of infection
85
example of resistance in food
E. coli O157 in spinach and lettuce
86
as foodborne infection increase
use of antibiotics increase - resistance increases
87
immunocompromised people
HIV, organ transplant recipients - increase use of antibiotics - increased resistance
88
emerginc disease
not seen before
89
remerging disease
caused by organisms resistant to treatment (Ebola)
90
clinical success of antibiotics led to
increasing efforts to discover new antibiotics
modification of existing drugs
develop broader range drugs
91
plasmids containing gene for resistance can
integrate into chromosome
92
resistance island
resistance genes can accumulate and are stably maintained
93
resistance can be shared cell to cell via
conjugation w/ sex pillus
94
microorganisms producing antibiotic substances hace autoprotective mechanisms
transmembrane proteins pump out freshly produced antibiotic so it does not accumulate
95
genes that code for pumps closely linked to genes that code for antibiotics meaning
close on chromosome, cannot be separated during crossover; activated/deactivated together
96
how to be resistant to antibiotics
inactivation of antibiotic
efflux pumping of antibiotic (pumping out)
modification of antibiotic target
alteration of metabolic pathway
97
inactivation of antibiotic
enzymatic breakdown of antibiotic molecule
98
B-lactamase
secrete into bacterial periplasmic space, attacks antibiotics as it approaches its target
99
how may forms of B-lactamase
more than 190
100
efflux is what type of transport
active - requires ATP
101
efflux proteins found in
plasma membrane - gram negativee
102
efflux keeps antibiotic levels
below lethal level
103
genes that code for efflux located on
plasmid or transposon (jumping gene)
104
some bacteria reduce permeability to keep antibiotic out by
turn of production of porin and other channel membran proteins - must slow metabolic activity
105
reduced production of porin seen in resistance to
streptomycin, tetracycline, sulfa drugss (penicillin, etc.)
106
modification of target to escape antibiotic activity
can change structure of target but still must be functional
| MRSA and PBP protein
107
alteration of metabolic pathway
drugs competitively inhibit metabolic pathway, bacteria can overcome this by using different pathway
108
how much of S. aureaus genome codes for resistance
7%
109
bacillus subtilis
nonpathogenic bacteria, does not code for resistance
110
cephalosporins
broad range drugs - lead to rise of resistance
111
clostridium difficile
superinfection pathogen - very resistant to antibiotics; establish in intestinal tract, my be dormant or chronic illness
