1. CHAPTER 6 MICROBIAL GROWTH-
GENERAL MICROBIOLOGY
CHAPTER 6 MICROBIAL GROWTH-
INCREASE IN _________
OF MICROBIAL _______

2. MICROBIAL GROWTH REQUIREMENTS
PHYSICAL
temperature
_______
__________
CHEMICAL
Carbon (C)
Oxygen (O)
Nitrogen (N)
Sulfur (S)
Phosphorus
Organic growth factors
Trace elements

3. PHYSICAL REQUIREMENTS for GROWTH :
TEMPERATURE
_________GROWTH TEMPERATURE
Lowest temperature at which a species will grow
__________GROWTH TEMPERATURE
Temperature at which species will grow ____
MAXIMUM GROWTH TEMPERATURE
_______ temperature at which growth is possible

4. CLASSIFICATION OF MICROBES:
TEMPERATURE RANGE of GROWTH
PSYCHROPHILES - cold loving microbes
Optimum growth temperature: _________
Capable of growing at 0oC, but not at 250C
Found in ocean depths, polar regions
Psychrotrophs-less temperature sensitive, some food spoilage
___________ - moderate temperature loving microbes
Optimum growth temperature: __________
Most common microbes
Food spoilage and disease
THERMOPHILES - _____loving microbes
Optimum growth temperature: 50-60oC
Minimum growth temperature: 45oC
Found in hot springs, compost piles

5. ACID BASE CHEMISTRY pH scale - logarithmic scale used to measure
____ – a substance that dissociates into hydrogen ions (H+) and negative ions in aqueous solution
Ex. Hydrochloric acid, citric acid
____ – a substance that dissociates into hydroxide ions (OH-) and positive ions in aqueous solution
Ex. Sodium hydroxide
pH scale - logarithmic scale used to measure
H+ concentration

6. PHYSICAL REQUIREMENTS for GROWTH cntd.: pH
Most bacteria grow between pH __________
Molds and yeast grow between pH _________
Acidophiles grow in acidic environments
_______ – compounds that keep ___ from changing drastically; ex. peptones, amino acids, phosphate salts-very important in the preparation of microbial media!!

7. PHYSICAL REQUIREMENTS for GROWTH cntd.
Osmotic Pressure
the force used by a solvent in moving from an area with a lower _____concentration to an area of higher __________concentration
_____ environments - concentration of solute (ex. salt or sugar) is higher outside cell, causes plasmolysis
Results in loss of water from a cell
Inhibits ______________
Used to preserve food, ex.Salted fish
__________ - require higher salt
concentrations in their environment
and therefore high osmotic pressure

8. ________ REQUIREMENTS for GROWTH
Nitrogen
In amino acids, proteins
Sulfur
In amino acids, thiamine, biotin
Some bacteria use SO42 or H2S
Phosphorus
In DNA, RNA, ATP, and membranes
PO43 is a source of
phosphorus
Trace Elements
Inorganic elements required in small amounts: Fe, Cu, Mb, Zn
Organic Growth Factors
Organic compounds obtained from
the environment
Vitamins, amino acids, purines, pyrimidines
Carbon
Structural organic molecules, energy source
Chemoheterotrophs
use _______________ sources
Ex. Humans, fungi, protozoa, most bacteria, helminths
Autotrophs -use ______
as carbon source
Ex. Plants

9. CHEMICAL REQUIREMENTS for GROWTH cntd. - OXYGEN
Obligate _______-O2 is required for growth
Facultative anaerobes- growth ___ _____ when O2 not present, O2
preferred
Obligate anaerobes-no growth when O2 present-_____ by O2
Aerotolerant anaerobes-can _______ O2 but can’t use it for growth
Micro-
aerophiles need very low O2 concentrations

10. _______ FORMS of OXYGEN Produced in small amounts during normal metabolic processes-harmful to cells
Some Forms of Toxic Oxygen
Superoxide free radicals (O2-1) – very unstable, steal electrons from cellular molecules
Peroxide anion (O2-2) – contained in hydrogen peroxide
Hydroxyl radicals (OH-) – most reactive
MECHANISMS of ELIMINATION
Superoxide free radicals (02-1)
H+ superoxide _____
dismutase
Peroxide anions (02-2)
2H2O2 ________ 2H2O + O2
H2O H+ peroxidase 2H2O

11. _________ CULTURE METHODS
1. Reducing media
contains chemicals (sodium thioglycolate) that combine with O2
Media is heated to drive off O2
2. OxyPlates
_________________ that reduces oxygen to water is added to growth
media, transforms petri plate into an anaerobic chamber
3. ANAEROBIC JAR
4. ANAEROBIC CHAMBER

12. _______________
Def.: Bacteria that require high ______ concentration

13. ____________ Microbial communities Form _____ or hydrogels
Bacteria attracted by _________ via quorum sensing
Share nutrients
Sheltered from harmful factors
Figure 6.5

14. CULTURE MEDIA important terms
Culture Medium: ________ (or any material) prepared for the growth of microbes in a laboratory
Sterile: No ________ microbes
Inoculate: Introduction of microbes into medium
Culture: Microbes growing in/on culture medium
_____ culture - contains only one species or strain of bacteria
Agar: Complex _________ (from marine algae)
Used as solidifying agent for culture media in Petri plates, slants, and deeps
Generally not metabolized by microbes
Liquefies at 100°C
Solidifies ~40°C

15. CULTURE MEDIA
Chemically Defined Media: Exact chemical composition is known
____________Media: Exact chemical composition not known; Extracts and digests of yeast, meats (organs), or plants Ex. Nutrient broth, nutrient agar

16. CULTURE MEDIUM for __________ MICROORGANISMS

17. SELECTIVE MEDIA ___________ unwanted microbes and
encourage desired microbes.
Ex. Eosin Methylene Blue Agar(EMB) and MacConkey
agar-allows Gram (-) bacteria to grow but not
Gram (+) bacteria.
EMB Agar
EMB Agar
Figure 6.9b, c

18. DIFFERENTIAL MEDIA Lactose nonfermenter on MacConkey Agar
Used to _________ colonies of different microbes based on specific properties such as: lactose fermenting bacteria from lactose non-fermenting bacteria; Ex.: MacConkey and EMB agar
Lactose nonfermenter on MacConkey Agar
Lactose Fermenter on Mac Conkey Agar
Figure 6.9a

19. BOTH SELECTIVE and DIFFERENTIAL MEDIA
1.__________ Agar
SELECTIVE for Gram (-) bacteria
DIFFERENTIAL
2. ___________________ (EMB )Agar
SELECTIVE for Gram (-) bacteria
DIFFERENTIAL

20. ___________ MEDIA nutritionally fortified media which encourages the growth of a wide range of microorganisms
Blood Agar Plate
also differential

21. ISOLATED COLONIES on AGAR PLATE
____________ METHOD
PROCEDURE for STREAKING for ISOLATION
ISOLATED COLONIES on AGAR PLATE
Colony- a population of cells arising from a single cell or spore or from a group of attached cells
A colony is often called a colony-forming unit (CFU)

22. PRESERVING BACTERIAL CULTURES
Deep-freezing: -50°to -95°C
Lyophilization (_______________):
Frozen (-54° to -72°C) and dehydrated in a vacuum

23. ____________ in PROKARYOTES
________________
________________
Budding
Conidiospores (actinomycetes)
Fragmentation of filaments

24. Bacterial _______________ Curve
GENERATION
TIME:
Time required for a cell to____________
Figure 6.13

25. FOUR PHASES of TYPICAL BACTERIAL_GROWTH
Figure 6.15

26. METHODS to DETECT and MEASURE BACTERIAL __________ (__________)
DIRECT
_______________*
Filtration
Most Probable Number (MPN)
Direct _____________ Count*
INDIRECT
______________ Measurements*
Dry Weight Determination
Metabolic Activity Measurements*

27. Direct ________ Count Method
Inoculate Petri plates from ______________
______________
Used to count _______ bacterial cells only

28. DIRECT ____________ COUNT
The number of microbes in a _____________ of bacterial suspension are counted using a special slide
Ex.: PETROFF HAUSSER
Does not distinguish between ______________________

29. Estimating Bacterial Numbers by Indirect Methods
________
:Indirectly Measures number of cells present, ____________
Figure 620

30. Estimating Bacterial Numbers by Indirect Methods
Metabolic activity
Amount of certain metabolic products is in direct proportion to number of bacteria present
Examples:
_____________
___________ Production
Dry weight
Weight of packed cell mass is proportional to the number of cells in culture
Used for _________________