Summary
Summary Microbial biotechnology
- Course
- Biology 154
- Institution
- Stellenbosch University (SUN)
Summary of microbial biotechnology. One part in three part series. Includes info from slides, lectures and the textbook.
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Microbial BiotechnologyMicro-Organisms:
> Using microorganisms to do something useful
> Micro-organisms – bacteria, fungi and viruses
> Invention of microscope – allowed us to observe micro-organism and their anatomy
o First microscope à Antony van Leeuwen Hoek
o Different shapes of micro-organisms could be seen under the first microscope
Microbes – General
> The total biomass of life on earth has been estimated at about 450 billion tons. Of that,
280 billion tons is comprised of microbes. So, about 60% of all biomass is composed of
microscopic organisms of which millions can fit onto a needle point.
> Microbes grow fast
o The main micro-organism in laboratory = E.coli (Bacteria)
o Doubles every 15 – 30 minutes under laboratory conditions
o Exponential growth rate – produce larger amount of biomass after many more
generations
> Micro-Organisms live everywhere
> More than half of the biomass of the planet comes from micro-organism
Growth Characteristics of Microbes
> So, despite their numbers, exponential growth and generation time, bacteria have not
taken over the world. Why? Because, like any other organism, their growth is limited by
the availability of nutrients (grown with optimal amount of nutrient in a laboratory à grow
very fast) and by the build-up of their own toxic by-products (produced to remove
competition from the environment they are living) .
> Bacterial growth curve
o Lag phase – grow slowly
o Log/exponential phase – no limitations, lots of nutrients
o Nutrients become limiting when population too big. Can’t increase anymore à
stationary phase
o Start dying off because of toxins they put into environment to kill or competing
bacteria
o Long-term à stationary phase where they can produce cysts which survive many
years, until they become resurrected.
> We can thus see that if we wish to use a bacterial culture for biotechnological purposes,
the growth conditions need to be very carefully controlled.
,Microbes can be Disease-Causing
> Epidemic: disease which is spreading widely, within a localised area. In city, or small
geographical area
> Pandemics are epidemics that spread over a wide geographical area
o Plague
o Smallpox à killed around 300-500 million people in the 20th century. Vaccines
allowed for the eradication of this
o HIV
o Ebola
o Zika
o Covid-19
> Spanish Flu infected 500 000 000 people between 1918 and 1920, killing between
50, 000, 000 – 100 000 000 (by comparison HIV has killed about 35 000 000 people)
o H1N1 virus responsible for Spanish Flu
Biological Warfare
> First recorded case of biological warfare was in 1348
> A Mongol army invading Europe catapulted the bodies of soldiers who had died of plague
into a city in Crimea. It is thought that this lead to the black death pandemic that killed 75
million people worldwide, and 1/3 of the population in Europe.
> Biological warfare is clearly bad à we can combat it using MODERN TECHNOLOGY
Smallpox
> Smallpox killed between 300-500 000 000 people in the 20th century alone. 30% of
individuals infected with the virus died
> Vaccines. To combat smallpox, people have infected themselves with the closely related
cowpox for centuries. Production led to mass vaccination programs
> The smallpox eradication program was run by the WHO between 1966 and 1980 and used
vaccination as a major weapon to remove this virus from the human population.
> The smallpox vaccine uses a virus that is closely related to both cowpox and smallpox. It
causes a mild infection but provides almost complete resistance to smallpox
> Endemic Smallpox was eradicated in 1977, although there was also one death in 1978
caused by accidental infection in a laboratory in UK
> Smallpox virus stocks are kept in two places worldwide, one in the IS and one in Russia,
Kept in case of re-emergence
Vaccines
> Vaccines can also be made using genes
from the disease causing agent, which are
expressed in a non-pathogenic organism,.
Means that there is no possibility of
infection when the vaccine is used.
> Leads to immunity
> Polio – heated and disarmed, can’t affect
people but body can recognise and
produce antibodies
> Modern way: make recombinant protein
, o Take a virus, one protein recognises human body and used to make anti-bodies
o Take the gene that codes for the one protein that causes the antibody response
o Insert that gene into a plasmid
o Plasmid into yeast cell – makes virus protein
o Grow yeast cell and isolate protein – purify
o Inject into people, body recognises protein
o When you are infected, body recognises and makes antibody
> Can be made in bacteria and plants
> Gene from organism that cause disease – make protein and use as vaccine = quick and
useful way for making vaccine
> Difficulty is finding the protein, then safety stages of human trials
> Vaccination is important because of herd immunity
o Helps people who cannot be vaccinated or are immunocompromised
o Covid-19 – let vaccine run through population, 60-80% of population, enough
infected and immune can stop spread of disease
o Concept when people started vaccination programs
o Increase number of people who become vaccinated, decrease spread of disease
(immunity)
o Introduce herd immunity into populations to stop disease from spreading
Biological Warfare Continued:
> Is it possible to make disease causing agents more dangerous?
o More infectious
o Resistant to antibiotics
o More deadly
o Overcome immunity from current vaccines……
> We could, for example, overcome antibiotics by taking known antibiotic resistance
genes and make them better at resisting antibiotics e.g. they lead to resistance against
more than one antibiotic or can resist higher amounts.
> Bacteria contain genes that make them resistant to antibiotics – increase amount
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