Microbial Biotech Flashcards
What method is used to test new microbial isolates for antibiotic production
Cross streak method
Steps in producing antibiotic from soil sample
- Spread soil dilution on a plate of selective media
- Incubation
- Overlay w an indicator organism
- Incubate
Testing activity spectrum steps
- Streak antibiotic producer across one side of plate
- Incubate to permit growth & antibiotic production
- Antibiotic diffuses into agar
- Cross streak w test organism
- Incubate to permit test organisms to grow
- Observe inhibition zones where sensitive organism did not grow
What does antibacterial activity appear as on plate
Appears as zone of inhibition
What kind of antibiotics are penicillins
Beta lactam antibiotics (as they have beta lactam ring structures)
What kind of penicillans are there
Natural, biosynthetic, semisynthetic penicillins
What kind of spectrum of activity have penicillins
Broad spectrum of activity
What phase of growth are penicillins produced in
They are secondary metabolites so produced in the stationary phase of growth
When does penicillin production start
After near exhaustion of the carbon source
High levels of what represses penicillin production
Glucose
What does nutrient feeding do for penicillin production
Nutrient feeding keeps penicillin production high for several days
What is added to penicillin fermentation to produce biosynthetic penicillin 1, 2 and 3
Precursor 1,2 and 3 are added respectively
What is done in penicillin fermentation to get natural penicillins
Chemical / enzymatic treatment of penicillin G
What is done in penicillin fermentation to get semisynthetic penicillin
Chemical/enzymatic tx of penicillin G.
Forms 6-Aminopenicillanic acid.
Side chains are added chemically.
Forms semisynthetic penicillins
Examples of semisynthetic penicillins
Ampicillin
Amoxycillin
Methicillin
Extracellular enzymes
Enzymes that are excreted into the medium instead of being held within the cell, they are extracellular
What can exoenzymes digest
Insoluble polymers - cellulose, protein, starch
Why are enzymes useful as industrial catalysts (2)
- Produce only one stereoisomer
- High substrate specificity
What are enzymes produced from
Bacteria & fungi
What are bacterial proteases used in
Laundry detergents
What are bacterial proteases isolated from
Alkaliphilic bacteria
What do amylases & glucoamylases produce
High fructose syrup
What is high fructose syrup produced from
Amylases & glucoamylases
What are extremozymes
Enzymes that function at some environmental extreme (pH or temp)
What are extremozymes produced by
Extremophiles
Applications of amylase (starch digesting)
- Bread
- Starch coatings (paper industry)
- Syrup & glucose manufacturing
- Digestive aid (pharmaceutical industry)
- Removal of stains, detergents
Applications of protease
- Bread
- Meat tenderising
- Wound cleansing
- Desizing (textile industry)
- Household detergent
What is the optimum growth temp of pullanase from Pyrococcus woesei
It’s a thermophile w opt growth temp of 100 degrees C, enzyme denatures at 110 degrees C
What are immobilised enzymes attached to
A solid surface
In what industry are immobilised enzymes used
The starch processing industry
Three ways to immobilise an enzyme
- Bonding of enzyme to carrier
- Cross linking of enzyme molecules
- Enzyme inclusion (entrapment & encapsulation)
What could enzyme inclusion occur in
- In fibrous polymers
- In microcapsules
What is immobilisation
A technique used to trap enzymes or yeast cells so that they can be reused in order to save money
What is the immobilisation process also known as and why
Also known as Continuous Flow Processing as products can be continually made.
2 examples of when immobilised enzymes are used
- In the production of lactose free milk
- In glucose testing strips to measure glucose levels in diabetics
What happens to lactose in the production of lactose free milk
- Milk flows through alginate beads with immobilised lactase
- Immobilised lactase converts lactose into glucose and galactose as the milk flows through
What does top fermenting in the brewing industry produce
Ales
What does bottom fermenting in the brewing industry produce
Lagers
Principle of fermentation for brewing industry
Yeasts convert sugars in wort (liquid extracted from mashing of barley) to ethyl alcohol and CO2
What yeast is commonly used in top fermenting
Saccharomyces cerevisiae
How long does top fermenting take and at what temp
5-7 days at 15-20 degrees C
What happens to the Saccharomyces cerevisiae in top fermenting
Rises to the top with the CO2
What yeasts are commonly used in bottom fermenting and what happens to them during this process
S. uvarum & S. carlsbergensis
The yeast falls to the bottom during fermention
How long does bottom fermenting take and at what temp
12-14 days at 5-15 degrees C
What happens during the process of lagering
Lagers are stored at 0-3 degrees for 4-6 weeks to allow a slow secondary fermentation take place
What must yeast strains do for good fermentation (3)
- Produce an active fermentation in wort
- Form aggregates easily at end of the fermentation
- Produce volatile acids & higher alcohols that contribute to flavour & aroma
What kinds of anaerobes are brewers yeast strains
Facultative anaerobes - can grow in presence or absence of O2
What is the Crabtree effect
The use of fermentation in the presence of O2 and at high glucose concentrations
