Chapter 5 And 6

Front 1

Temperature

Back 1

Minimum growth temperature
Optimum growth temperature
Maximum growth temperature

Front 2

psychrophiles

Back 2

cold loving; grow at 0oC; optimum about 150C; will not even grow in a reasonably warm room; ocean depths; polar regions

Front 3

psychrotrophs

Back 3

grow at 0oC; optimum 20-30oC; cannot grow above 40oC; common; low temperature food

Front 4

spoilage

Back 4

(moderate psychrophiles or facultative psychrophiles); do not grow well at low temperatures, except in comparison with other organisms; given time will slowly degrade food; mold mycelium; slime layer; off tastes and colors

Front 5

Mesophiles

Back 5

optimum growth 25-40oC; most common type of microbe; optimum temperature for many pathogenic bacteria - 37oC; include most of the common spoilage and disease organisms

Front 6

thermophiles

Back 6

capable of growth at high temperatures; optimum growth 50-60oC; sunlit soil and in thermal waters and hot springs; many cannot grow below about 45oC; not considered a public health problem; in organic compost piles

Front 7

hyperthermophiles

Back 7

(extreme thermophiles) in hot springs associated with volcanic activity; sulfur important in metabolic activity; 1100C at hydrothermal vents

Front 8

Psychrotrophs

Back 8

Grow between 0°C and 20–30°C
Cause food spoilage

Front 9

Most bacteria grow between?

Back 9

pH 6.5 and 7.5

Front 10

Molds and yeasts grow between?

Back 10

pH 5 and 6

Front 11

Acidophiles

Back 11

grow in acidic environments

Front 12

most bacteria grow best between

Back 12

pH 6.5-7.5

Front 13

very few bacteria grow at pH below 4 but those that do?

Back 13

acidity from fermentation used as preservative [sauerkraut, pickles and many cheeses])many bacteria produce acids so buffers are added to growth media (peptones and amino acids and phosphate salts)

Front 14

optimum of molds and yeasts

Back 14

pH 5-6

Front 15

acidophiles

Back 15

chemoautotrophs oxidize sulfur to sulfuric acid (Thiobacillus) pH of 1

Front 16

Osmotic Pressure

Back 16

Hypertonic environments, or an increase in salt or sugar, cause plasmolysis
Extreme or obligate halophiles require high osmotic pressure
Facultative halophiles tolerate high osmotic pressure

Front 17

most bacteria prefer to live in?

Back 17

hypotonic situations; if in this solution plasmolysis occurs (plasma membrane pulls away from cell wall) - cell growth inhibited

Front 18

high salt or sugar concentrations are used for?

Back 18

preserve food; salted fish, honey, sweetened condensed milk

Front 19

extreme halophiles

Back 19

require high salt concentrations for growth (obligate halophiles) - require nearly 30% salt

Front 20

facultative halophiles

Back 20

tolerate salt concentrations up to 2% (15%)

Front 21

solute concentration of agar

Back 21

1.5%

Front 22

Carbon

Back 22

Structural organic molecules, energy source
Chemoheterotrophs use organic carbon sources
Autotrophs use CO2

Front 23

Nitrogen

Back 23

In amino acids and proteins
A few bacteria use N2 in nitrogen fixation

Front 24

Sulfur

Back 24

In amino acids, thiamine, and biotin
Most bacteria decompose proteins
Some bacteria use SO42– or H2S

Front 25

Phosphorus

Back 25

In DNA, RNA, ATP, and membranes
PO43– is a source of phosphorus

Front 26

Sulfur

Back 26

cysteine and methionine, coenzyme A, thiamine and biotin
Our Winogradsky column will illustrate the sulfur cycle - handout coming
Sources of sulfur: sulfate ion (SO42-), hydrogen sulfide (H2S), sulfur containing amino acids (cysteine and methionine)

Front 27

Phosphorus

Back 27

phospholipids, ATP, nucleic acids
sources: phosphate (PO43-)
Other requirements: potassium, magnesium, calcium and trace elements that are usually present in tap water (iron, copper, molybdenum, zinc)
Most of the above function as cofactors to enzymes; calcium is also a second messenger

Front 28

Oxygen - O2

Back 28

a poisonous gas
very little existed in atmosphere during most of Earth’s history
poorly soluble in water
life could not have arisen had oxygen been present

Front 29

obligate aerobes

Back 29

use molecular oxygen - aerobic respiration - die without it

Front 30

facultative anaerobes

Back 30

aerobically respire but can also survive and grow without oxygen using fermentation or anaerobic respiration They grow more slowly when oxygen is absent.

Front 31

Obligate anaerobes

Back 31

killed by oxygen - ferment or anaerobically respire (Clostridium)

Front 32

aerotolerant anaerobes

Back 32

do not aerobically respire (either ferment or anaerobically respire) but can tolerate the presence of oxygen (Lactobacillus

Front 33

microaerophiles

Back 33

aerobically respire but cannot tolerate oxygen levels of the present atmosphere

Front 34

Toxicity of oxygen

Back 34

many toxic forms will occur in its presence

Front 35

singlet oxygen

Back 35

(O2) boosted to a higher-energy state
extremely reactive - used in phagocytic cells where it is produced and used to kill ingested bacteria (some bacteria are resistant)

Front 36

superoxide free radicals

Back 36

(O2-)
formed in small amounts during normal aerobic respiration
MUST be detoxified. Very unstable; steals electrons from neighboring molecules

Front 37

singlet state

Back 37

If triplet oxygen absorbs sufficient energy to reverse the spin of one of its unpaired electrons, it will form the singlet state, in which the two electrons have opposite spins (Fig. 1). This activation overcomes the spin restriction and singlet oxygen can consequently participate in reactions involving the simultaneous transfer of two electrons (divalent reduction). Since paired electrons are common in organic molecules, singlet oxygen is much more reactive towards organic molecules than its triplet counterpart. 1O2

Front 38

Superoxide O2-

Back 38

is an anion with the chemical formula O2−. It is important as the product of the one-electron reduction of dioxygen O2, which occurs widely in nature.[1] With one unpaired electron, the superoxide ion is a free radical, and, like dioxygen, it is paramagnetic.

Front 39

superoxide dismutase (SOD)

Back 39

is an enzyme that neutralizes superoxide free radicals; converts them to H2O2 - hydrogen peroxide; O2- + O2- + 2H+ H2O2 + O2

Front 40

Peroxide ion: O22-

Back 40

present in hydrogen peroxide
neutralized by enzyme catalase: 2H2O2  2H2O + O2
[We will be using a test for the presence of this enzyme. A drop of hydrogen peroxide will be dropped on a colony of bacteria. If catalase is present, what should you observe?]

Front 41

peroxidase

Back 41

another enzyme that breaks down hydrogen peroxide: H2O2 + 2H+  2H2O

Front 42

hydroxyl radical (OH·):

Back 42

probably the most dangerous
formed by ionizing radiation; aerobic respiration produces transient traces

Front 43

Peroxide anion O22-

Back 43

This H2O2 contains a peroxide anion, which is a negative ion.
This molecule is a highly reactive oxidant.
H2O2’s main effect against as an antimicrobial agent is due to the peroxide anion.

Front 44

Organic Growth Factors

Back 44

Organic compounds obtained from the environment

Front 45

Bacteria attracted by chemicals via

Back 45

quorum sensing

Front 46

Patients with indwelling catheters received

Back 46

contaminated heparin

Front 47

Nosocomial infections

Back 47

Nearly all indwelling catheters become contaminated with a biofilm

Front 48

biofilm

Back 48

is an aggregate of microorganisms in which cells are stuck to each other and/or to a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS). Biofilm EPS, which is also referred to as "slime," is a polymeric jumble of DNA, proteins and polysaccharides. Biofilms may form on living or non-living surfaces, and represent a prevalent mode of microbial life in natural, industrial and hospital settings

Front 49

Pseudomonas fluorescens

Back 49

was cultured from the catheters

Front 50

Culture medium

Back 50

Nutrients prepared for microbial growth

Front 51

Sterile

Back 51

No living microbes

Front 52

Inoculum

Back 52

Introduction of microbes into medium to initiate growth

Front 53

Culture

Back 53

Microbes growing in/on culture medium

Front 54

Agar

Back 54

Used as solidifying agent for culture media in Petri plates, slants, and deeps
Generally not metabolized by microbes

Front 55

Anaerobic Culture Methods

Back 55

Reducing media
Contain chemicals (thioglycolate or oxyrase) that combine O2
Heated to drive off O2

Front 56

Capnophiles

Back 56

Microbes that require high CO2 conditions
Also microaerophiles
CO2 packet
Candle jar
Campylobacter

Front 57

Mycobacterium leprae

Back 57

usually grown in armadillos [they have low body temperature]

Front 58

Treponema pallidum

Back 58

syphilis spirochete; obligate intracellular bacteria (rickettsias and chlamydias) - grown in cell cultures

Front 59

Selective media

Back 59

suppress the growth of unwanted bacteria and encourage the growth of desired microbes

Front 60

Sabouraud’s dextrose agar

Back 60

pH 5.6 - used to isolate fungi that outgrow most bacteria at this pH (acidic)

Front 61

Differential media

Back 61

make it easier to distinguish colonies of the desired organism from other colonies on the same plate

Front 62

blood agar

Back 62

contains red blood cells - some bacteria can lyse these cells

Front 63

Streptococcus pyogenes

Back 63

beta hemolytic - leaves a clear area around the colony

Front 64

alpha hemolytic

Back 64

bacteria leave a green area around their colonies

Front 65

Mannitol salt agar

Back 65

contains a pH indicator, mannitol as only carbohydrate and 7.5% sodium chloride - selects for and differentiates colonies of Staphylococcus aureus which can tolerate the high salt concentration and can ferment mannitol to acid

Front 66

MacConkey agar

Back 66

contains bile salts, crystal violet, lactose, pH indicator
inhibits the growth of gram-positive bacteria with bile salts and crystal violet (selective)
shows production of acid from lactose with pH indicator (differential)

Front 67

eosin methylene blue (EMB)

Back 67

colonies of Escherichia coli will have black centers and a metallic green sheen
Enterobacter aerogenes colonies will have dark centers

Front 68

streak plate method

Back 68

method for isolating pure cultures
isolated colonies in the last streak are transferred to sterile media to form a pure culture

Front 69

binary fission

Back 69

bacterial cell division

Front 70

Lyophilization

Back 70

(freeze-drying): Frozen (–54° to –72°C) and dehydrated in a vacuum; to persevere bacterial cultures

Front 71

Phases of growth

Back 71

lag phase;log phase;Stationary phase;death phase

Front 72

lag phase

Back 72

number of cells changes very little
1 hour to several days
intense metabolic activity in cells - tooling-up activity

Front 73

log phase

Back 73

exponential growth - generation time reaches a constant minimum - straight line when graphed logarithmically

Front 74

Stationary phase

Back 74

number of deaths balances the number of new cells
metabolic activities slow
exhaustion of nutrients, accumulation of waste products, harmful changes in pH

Front 75

death phase

Back 75

number of deaths exceeds number of new cells
logarithmic decline
population becomes tiny or all cells die - some bacteria retain surviving cells almost indefinitely

Front 76

Most Probable Number (MPN) method

Back 76

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
chemoautotrophic nitrifying bacteria, coliform bacteria

Front 77

form of statistical analysis

Back 77

95% chance number is in a particular range

Front 78

turbidity

Back 78

increases with number of bacteria
absorbance increases - spectrophotometer
more than 1 million cells/ml must be present
about 10 million to 100 million cells/ml needed to use correctly

Front 79

metabolic activity

Back 79

assumes a certain amount of metabolic product, such as acid or carbon dioxide, is in direct proportion to the number of bacteria present

Front 80

Dry weight

Back 80

for filamentous bacteria and molds
fungus removed from growth medium, filtered and dried in a desiccator, then weighed

Front 81

Photosynthesis

Back 81

convert carbon dioxide to organic molecules
electromagnetic energy converted to chemical energy
chemical energy used to fix carbon dioxide to reduced carbon compounds, primarily sugars - carbon fixation

Front 82

oxygenic photosynthesis

Back 82

cyanobacteria, algae, plants
water is the source of the electrons that reduce carbon - oxygen produced as a byproduct
chlorophyll a always one of the pigments involved

Front 83

Photo

Back 83

Conversion of light energy into chemical energy (ATP)
Light-dependent (light) reactions

Front 84

Synthesis

Back 84

Carbon fixation: Fixing carbon into organic molecules
Light-independent (dark) reaction: Calvin-Benson cycle

Front 85

oxygenic photosynthesis

Back 85

the source of electrons is water and the most important pigment is chlorophyll a

Front 86

anoxygenic photosynthesis

Back 86

the source of electrons is something else such as H2S and the photosynthetic pigments are bacteriochlorophylls;bacteriochlorophylls in chlorosomes or chlorobium vesicles- green bacteria (such as Chlorobium); use sulfur, hydrogen sulfide or hydrogen gas as a source of hydrogen to reduce carbon; oxidize sulfide or sulfur to sulfate; or hydrogen gas to water
purple bacteria (such as Chromatium); bacteriochlorophylls in invaginations of plasma membrane; use sulfur, sulfur compounds or hydrogen gas to reduce carbon dioxide

Front 87

photoautotrophs

Back 87

use light energy
use carbon dioxide as a carbon source

Front 88

photoheterotrophs

Back 88

use light energy; alcohols, fatty acids or other organic molecules are needed as carbon source
green nonsulfur bacteria (Chloroflexus)
purple nonsulfur bacteria (Rhodopseudomonas)

Front 89

chemoautotrophs (lithotrophs)

Back 89

Chemoautotrophs - lithotrophs
oxidize inorganic compounds as a source of energy
carbon dioxide is the principal source of carbon; often through Calvin cycle
reduced inorganic compounds that are often used as sources of energy
hydrogen sulfide - Beggiatoa
elemental sulfur - Thiobacillus thiooxidans
ammonia - Nitrosomonas
nitrite ions - Nitrobacter
hydrogen gas - Hydrogenomonas
ferrous iron - Thiobacillus ferroxidans
carbon monoxide - Pseudomonas carboxydohydrogena

Front 90

chemoheterotrophs

Back 90

use organic molecules as a source of energy and carbon

Front 91

saprophytes

Back 91

live on dead organic matter

Front 92

Carbon fixation occurs by?

Back 92

reversal of the steps in the citric acid cycle (Krebs cycle)

Front 93

Bacteriochlorophylls

Back 93

can absorb electromagnetic radiation with wavelengths longer than visible light - into the infrared part of the spectrum. Therefore the electromagnetic radiation generated by heat provides enough energy for some of these bacteria (found at deep sea vents)

Front 94

Lithotrophs

Back 94

A large group of microbes are capable of using inorganic substances as their source of energy. They are termed lithotrophs, literally meaning rock eaters.

Front 95

polysaccharide biosynthesis

Back 95

to produce glycogen bacteria phosphorylate glucose; glucose 6-phosphate is added to ATP to produce adenosine diphosphoglucose ADPG - then polymerization occurs
in animals, synthesis of glycogen; glucose is phosphorylated to glucose 6-phosphate which is joined to UTP (uridine triphosphate) to form uridine diphosphoglucose (UDPG)
peptidoglycan synthesis in bacteria requires UDP-N-acetylglucosamine (UDPNAc)

Front 96

Amphibolic pathways

Back 96

Metabolic pathways that have both catabolic and anabolic functions