MICROBIAL CULTURE
(b) Explain the terms “batch culture” & “continuous culture”
(c) Compare advantages & disadvantages of batch and continuous culture with reference to the production of 20 metabolites (e.g: penicillin), enzymes (e.g: protease) and biomass (e.g: mycoprotein)
Use for human: Mining Antibiotic
(penicillin) Enzymes Biomass
(mycoprotein) etc.
Microorganisms
Batch Culture
= to grow cells in a closed system no input to or output from the system Cells are inoculated into the nutrient medium Incubated for a period of time for growth To promote the production of secondary
metabolites Growth curve
Growth Curve of Microbial Population
Advantages of Batch Culture
the culture is easy to set up the environmental conditions are relatively
easy to control the same vessel can be used for different
processes at different times (cost effective) if the culture becomes contaminated, it is only
one batch that is lost (cost effective) Suitable for the production of secondary
metabolite such as penicillin.
Continous Culture
= to grow cells in an open system Continuous input and output Input – fresh nutrient medium Output – used medium, cells &
products To maintain a constant environmental condition To maintain cells at exponential phase Continuous production of growth associated products
(e.g. biomass & 1o metabolites)
Continuous culture (Con’t) Growth curve:
Advantages of Continuous Culture
it can be carried out in smaller vessels growth and product formation at exponential phase
can be maintained for prolonged periods of time production is almost continuous Has higher productivity than batch culture for growth
associated products the high productivity for biomass and intra- and extra-
cellular enzymes is more cost effective Fermenter does not have to be emptied, cleaned and
refilled very often (< down time)
Disadvantages of Continuous Culture
blocking of inlet pipes due to microbial growth, clumping of cells and foaming
needs sophisticated equipment & highly trained staff to maintain constant environmental conditions.
difficult to control all the environmental factors not suitable for the production of secondary
metabolites.
A typical fermenter
Laboratory fermenters
Laboratory fermenter
Scaling up
fermenter
Scaling up
fermenter
Industrial fermenter
Industrial fermenter
Industrial fermenter
Recap
Batch culture Continuous culture Growth curve Advantages & disadvantages
Three examples of fermentation
Manufacturing penicillin Manufacturing enzymes Manufacturing mycoprotein
Manufacturing Penicillin
Inoculated m’org: Penicillium (fungus) Final product: Penicillin By fed batch culture
Add: Carbohydrate source (corn steep liquor)
Duration: Every 30 mins
10 metabolites: CO2 + ethanol20 metabolite: Penicillin
Penicillium
Manufacturing Enzymes
Important in industry, medicine or food technology
Manufacturing Enzymes
Enzyme production occurs in 2 stages: Growing of microorganisms Extraction, purification and concentration of
product (enzyme)
Manufacturing Enzymes
Inoculated m’org: Bacteria / fungus
Final product: Enzyme
Add: 1) Carbohydrate source (waste product) 2) Nitrogen source (urea, ammonium salts)
Enzymes
Manufacturing Enzymes
Thermophilic (heat-loving) organisms are used E.g: Bacillus stearothermophilus Live in hotsprings Can live up to 700C Used in products such as biological washing powders
Manufacturing Mycoprotein
Mycoprotein = fungus protein Mainly made by Fusarium graminearum
Fusarium graminearum
Manufacturing mycoprotein
A very good meat substitute High in protein, low in fat QuornTM is a very popular brand in Europe
and USA on mycoprotein product
Manufacturing mycoprotein
Inoculated m’org: Fusarium graminearum Final product: Mycoprotein By continuous culture Unlike normal fermentation, no stirrer is used.
