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

2. MICROBIAL GROWTH REQUIREMENTS
_________ pH
osmotic pressure
CHEMICAL
Carbon (C)
Oxygen (O)
Nitrogen (N)
Sulfur (S)
_____________
_____________ factors
Trace elements

3. PHYSICAL REQUIREMENTS for GROWTH :
TEMPERATURE
_________ GROWTH TEMPERATURE
_______ temperature at which a species will ______ (_________)
OPTIMUM GROWTH TEMPERATURE
Temperature at which species will grow _____
MAXIMUM GROWTH TEMPERATURE
___ temperature at which growth is possible

4. CLASSIFICATION OF MICROBES:
TEMPERATURE ___________________
_________PHILES - cold loving microbes
Optimum growth temperature: ________
Capable of growing at 0oC, but not at 250C
Found in ocean depths, polar regions
________-less temperature sensitive, some food spoilage
_________PHILES - moderate temperature loving microbes
Optimum growth temperature: _______
Most common microbes
Food spoilage and disease
___________PHILES heat loving microbes
Optimum growth temperature: _________
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 _________ ions ____ and negative ions in aqueous solution
Ex. Hydrochloric acid, citric acid
BASE – a substance that dissociates into ___________ ions (____) and positive ions in aqueous solution
Ex. Sodium hydroxide
pH scale - logarithmic scale used to measure
H+ concentration

6. PHYSICAL REQUIREMENTS for GROWTH cntd.: _____
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 __________!!

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

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

9. CHEMICAL REQUIREMENTS for GROWTH cntd. - OXYGEN
Obligate aerobes-O2 is _______ for growth
__________ anaerobes- growth can occur when O2 not present, O2
preferred
Obligate anaerobes-no growth
when __present-______ by O2
____tolerant anaerobes-can tolerate O2 but can’t use it for _______
Micro-
aerophiles need _______ O2 concentrations

10. ______ FORMS of _____________ Produced in small amounts during normal metabolic processes-__________________
Some Forms of _____________
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+ __________ H
dismutase
Peroxide anions (02-2)
2H2O2 ________ 2H2O + O2
_____ + 2H+ peroxidase 2H2O

11. ANAEROBIC ________ METHODS
1. _______ media
contains chemicals (sodium thioglycolate) that combine with O2
Media is heated to drive off O2
2. _________
enzyme (oxyrase) 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 ____________concentration

13. ____________ Microbial communities Form slime or hydrogels
Bacteria attracted by chemicals via _______ sensing
Share ____________
________ from harmful factors
Involved in _____of infections
___________, heart _____, contact lenses, dental caries
Figure 6.5

14. CULTURE MEDIA important terms
Culture Medium: ________ (or any material) prepared for the _________ of microbes in a laboratory
_________: No living microbes
Inoculate: __________ of microbes into __________
Culture: Microbes ________ in/on culture medium
Pure culture - contains only ______________ of bacteria
Agar: Complex ___________ (from marine algae)
Used as ____________ agent for culture media in Petri plates, slants, and ______
Generally not ____________ by microbes
Liquefies at 100°C
Solidifies ~40°C

15. CULTURE MEDIA
Chemically ______ Media: Exact chemical composition is known
-___________ microorganisms- they require many growth factors provided in chemically defined media.
_______ 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. ____________ 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
______ Agar
Figure 6.9b, c

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

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

20. ___________ MEDIA nutritionally fortified media which encourages the growth of __________________ of microorganisms
_____________ Plate
also differential

21. ISOLATED COLONIES on AGAR PLATE
STREAK PLATE METHOD
PROCEDURE for STREAKING for ____________________
ISOLATED COLONIES on AGAR PLATE
_________- 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. ___________ BACTERIAL CULTURES
Deep-freezing: ____________
Lyophilization (_____________):
Frozen (-54° to -72°C) and dehydrated in a vacuum

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

24. Bacterial __________ Growth Curve
GENERATION
TIME:
Time required for a _____________ in number
Figure 6.13

25. FOUR PHASES of TYPICAL ___________________________
Figure 6.15

26. METHODS to DETECT and ____________ BACTERIAL GROWTH _____________
_______________
_____________
Filtration
Most Probable Number (MPN)
Direct Microscopic Count*
INDIRECT
_____________ Measurements*
Dry Weight Determination
________ Activity Measurements*

27. Direct ___________ Method
Inoculate Petri plates from _____ ____________
Used to count _______ bacterial cells only

28. _________ MICROSCOPIC 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 ______ Methods
________
:Indirectly measures number of cells present, ___________
Figure 620

30. Estimating Bacterial Numbers by ______________ Methods
_____________ activity
Amount of certain metabolic products is in direct proportion to number of bacteria present
Examples:
O2 Consumption
Acid Production
_______________
Weight of packed cell mass is proportional to the number of cells in culture
Used for filamentous fungi