Growth and Physiology of Bacteria Flashcards
Bacteria have:
-High or low metabolic rate
-Long or short gen time
-Ability to use…
-high metabolic rate ; grow very quickly
-short generation time
-ability to use a vast array of energy sources both chemical (i.e. inorganic as well as organic) and physical (e.g. radiant energy) e.g can grow in disinfectants; will always outcompete mammalian cell as grow so rapidly
Bacteria replicate by…
Binary Fission
Bacterial growth is increase in no. or increase in size of cells?
^ in number of cells
-Bacterial cell daughter cells are of equal size true or false
-Do cells separate after division?
-True
-may or may no
Cocci gram positive or gram negative bacteria?
Gram +ve
2 types of cocci and their differences in growth
Streptococci- grow in chains
Staphylococci- grow in clumps/clusters
Chromosome replication in bacteria initiates…
Cell division; then proceeds in both directions until it reaches terminus
(Diagram of chromosome replication, don’t need to understand all of it, just the concept of movement of direction to terminus)
https://www.google.co.uk/imgres?imgurl=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F7%2F7c%2FOrigins_of_DNA_replication_Figure_1.jpg&imgrefurl=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FOrigin_of_replication&tbnid=ovZBCN-TbJtR9M&vet=12ahUKEwit_eLrmev8AhXnvicCHdpmC6wQMygAegUIARC5AQ..i&docid=4xazyyziHBhhJM&w=4945&h=4649&q=origin%20DNA%20replication%20and%20terminus%20in%20bacteria%20diagram&hl=en-gb&client=safari&ved=2ahUKEwit_eLrmev8AhXnvicCHdpmC6wQMygAegUIARC5AQ
2 ways of measuring bacterial growth in lab
In liquid or solid media
-Types of liquid media measurement of bacterial growth
-Types of solid media measurement of bacterial growth
-Turbidity
-Count particles
-Viable counts
-serial dilution
-What is turbidity type of measurement of bacterial growth
-What is Count particles type of measurement of bacteria growth
Use of absorbance of light on spectrophotometer or light scatter on nephelometer; start off with clear fluid and as bacteria grows it gets more cloudy so you can see the visible changes
Counting the number of cells of bacteria either microscopically or using an electronic particle counter
What is the generation/doubling time
Time it takes for population to divide and double
Under optimum conditions the doubling time is characteristic of each bacteria
Doubling time of bacteria greatly affected by… and is…
Culture conditions and is species specific
Name the Bacterial growth rates of these microorganisms
(Their doubling time in min)
-Vibrio natriegens
-Bacillus sterothermophilus
*-Escherichia coli
-Bacillus subtilis
*-Pseudomonas putidia
-Mycobacterium tuberculosis
- 9.6
- 8.4
- 22.8
- 25.8
- 45
- 360
Microorganisms grow slower in vivo or vitro?
In vivo
Name the bacterial growth curve phases
Lag phage
Log phase
Stationary phase
Describe each phase of bacterial growth curve
-lag phase
-log phase
-stationary phase
- Bacteria adjusting to environment and producing enzymes to allow it to use substrate
- Doubling rapidly
- Run out of nutrients to grow
Requirements for bacteria to grow
Physical requirements
-temp
-pH
-osmotic pressure
Gaseous requierments
Nutrients
What are mesophiles
Bacteria with optimum temp of 37C
What are neutrophiles
Pathogenic bacteria with an optimum pH of around 7
Products of bacterial metabolism are usually ________. Therefore pH for their growth can be ________.
Acidic
Lower
4 Types of growth of bacteria in semi solid media (relating to effect of oxygen on them)
- Obligate aerobe
- Facultative anaerobe
- Microaerophile
- Obligate anaerobe
What is the obligate aerobe type bacteria in semi solid media
-examples
Bacteria which in semi solid media gravitates to the surface where there is most oxygen; like to grow in oxygen
Microbacterium bovis, microbacteriumtberculosis
What is the facultative anaerobe type bacteria in semi solid media
Bacteria that grow aerobically and anaerobically (in absence of O2)
What is the microaerophile type bacteria in semi solid media
Bacteria that grow below surface of liquid as they prefer less O2 and more CO2
What is the obligate anaerobe type bacteria in semi solid media
-examples
Grow in absence of O2; it is toxic/fatal to them
-clostridium prefringes
Too much oxygen is ________ to bacteria
Toxic
How does oxygen intoxicate bacteria
By forming reactive oxygen intermediates (ROI)
Name the 3 types of ROI
superoxide
peroxide
hydroxyl radical
Which enzymes detoxify the ROIs
Superoxide dismutase
Catalase
Pathogenic bacteria are chemoheterotrophs. What does this mean?
They require a source of nutrients
List the nutrient requirements bacteria require
– Organiccarbon
– Nitrogen
– Sulphur
– Phosphorus
– Potassium
– Magnesium
– Calcium
– Trace elements
• Iron,Zinc,Copper,Molybdenum
What extra organic growth factors do some bacteria require?
NAD or NAD
Solid media
-is solidified by…
-Agar (1-3%) put into a petri dish (plate)
Bacteria grow as colonies. Each colony arises from…
Growth of a single bacterial cell or clump of cells
What is streaking of bacteria on agar plate
Movement of bacterial colonies across plate to dilute bacteria to grow individual colonies and identify them
When making a bacterial sample in the lab, some bacteria need an enriched media. Name substances used to help the bacteria grow
Blood, serum, chocolate agar (heated blood agar)
What is horse blood agar used to grow and why
What is sheep blood agar used for
Anaerobic bacteria because it gives better haemolysis than other blood
Aerobic bacteria
Agar that we use to grow bacteria is differential and selective. What does this mean
Selective; contains inhibitory substances to prevent some bacteria from growin
Differential; contains a sugar (lactose). If the organism metabolises lactose it produces acid and the colonies become pink. This allows us to identify the colony being grown
Which bacteria; gram +ve or gram -ve ferment lactose and therefore colones will turn pink in an agr
Gram positive!
Cultivation of fungi
-fungi are chemoheterotrophs true/false
-require complex substances such as…
-optimum growth temp and pH
-common agar media used
-yeast grown as colonies however filamentous fungi grown as a ___________
• Fungi are chemoheterotrophs
• Growth requirements similar to bacteria some require complex substances such as keratin
• Optimum growth temperature for many fungi much lower than for pathogenic bacteria
• Most fungi grow at lower pH than bacteria
• Media
– Sabouraudsagar
– Dextrose and peptone, pH5.6
• Yeast grow as colonies
• Filamentous fungi grow as a mycelium
What is mycelium
root-like structure of a fungus consisting of a mass of branching, thread-like hyphae
What is sterilisation
Killing or removal of all living organisms in or on a substance or object, usually by denaturing proteins, nucleic acids and membrane permeability
What is disinfection
Killing of most microorganisms on a substance or object (kill may not be complete – removes a high % of organisms to numbers too low to cause disease)
What are sterile techniques
Procedure carried out in absence of living things
Used in surgery
What are aseptic techniques
Procedures performed in a way to prevent contamination with infectious microorganisms
Used in laboratory
Methods of sterilisation
• Irradiation
• Heat
– Moist
–boiling, autoclave
– Dry– hot air oven
• Filtration
• Chemicals
– Ethyleneoxide
– Formaldehyde and Gluteraldehyde
– Hydrogen peroxide
– Chlorinedioxide
– Peraceticacid
•
Ionising radiation – disposable plastics, surgical materials, unsuitable for glass and metal
Describe how heat works as a method of sterilisation
-what methods of heating would you use
Denatures enzymes- coagulation of proteins and breakage of H bonds
-boiling, autoclave
REMEMBER TO KILL THE BACTERIA U MUST KILL THE BACTERIAL SPORES OR ELSE IT IS NOT A STERILISING METHOD
Yuh
What is autoclave
Steam under pressure
Materials and objects that require sterilisation
Microbiological and tissue culture.
Medicines.
Surgical, optical and electrical instruments.
Reagents.
Equipment or containers in which any of the above are to be handled.
Infected material.
Factors affecting the action of a disinfectant
Period of exposure
Concentration (there is an optimum dilution for disinfectant)
Temperature
pH
Organic matter
Number of bacteria present
