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2. 3: MICROBES AND BIOTECHNOLOGY
Traditional classification systems have
recognized 2 categories of organismsm based
on cell types:
- EUKARYOTES
- PROKARYOTES

3. Domains of life:
based on ribosomal RNA (rRNA)

4. BACTERIA ARCHAEA EUKARYOTA
HISTONES Absent Proteins similar to Present
ASSPCIATED WITH histones bond to
DNA DNA
PRESENCE OF Rare or absent Present in some Frequent
INTRONS genes
STRUCTURE OF CELL Made of chemical Not made of Not made of
WALLS called petidoglycan peptidoglycan peptidoglycan; not
always present
CELL MEMBRANE Glycerol-ester lipids; Glycerol-ether Glycerol-ester lipids;
DIFFERENCES unbranched side- lipids; unbranched unbranched side
chains, d-form side-chains, I-form chains: d-form of
glycerol of glycerol glycerol

5. ARCHAEA
• Found in a broad range of habitats:
- Ocean surface
- Deep ocean sediments
- Oil deposists
They are always found in very extreme conditios.
Example:
1) Halophiles  water with high salt concentrations
2) Thermophiles  Close to boiling water Tº
3) Methanogens  anaerobes, give off methane in
cattle’s intestine

6. Diversity of EUBACTERIA

7. 1) Coccus: spherical bacteria
2) Baccilus: rod-shaped bacteria
3) Vibrio: comma shaped rods
4) Spirilli: twisted bacteria
Some bacteria can group together to form
AGGREGATES:
Prefix “strepto-”  form filaments
Prefix “ staphylo-”  form clusters
Ex: Staphylococcus form spherical clusters.

8. Biofilms
Biofilm  a surface – coating colony of
organisms.
Pseudomonas aeruginosa produces biofilms in
burned patients and in patiens with cystic
fibrosis. Its is easuer this way for bacteria to
acquire resistance to antibiotics because they
can cooperate and interact in different ways

9. Autoinducers
Autoinducers: help coordinate the action of a
group of bacteria.
Vibrio fischeri is a bacterium found in sea water that
is able to bioluminiscence  emit light. Individuals
do not emit light unless they become part of a
population of certain density. V. Fischeri releases an
autoinducer into its surroundings. In a dense
population, the concentration of the inducer
becomes high enough to trigger bioluminiescence.

10. Gram cell wall

11. Gram cell wall
A traditional test used to classify bacteria is
wether they are Gram-negative or Gram-
positive, based on how they react to Gram-
staining.
The cell wall of Gram-positive bacteria consists of many layers of
peptidoglycan ( a polymer consisting of amino acids and sugars). These
layers are connected by amino acid bridges.
The cell wall of Gram-negative bacteria is much thinner (only about 20%
peptidoglycan). Gram-negative have 2 unique regions that surround the
outer plasma membrane ( the periplasmic space and the
lipopolysaccharide layer). The periplasmic space separates the outer
plasma membrane from the peptidoglycan layer.

12. VIRAL DIVERSITY
A VIRUS is a biological structure that is organized but
non- cellular.
It can reproduce only within a host cell.
Viruses consist of NUCLEIC ACID covered by a protein
coat called CAPSID.
Some capsids are covered in a membranous bilayer
derived from the membrane of the host cell that
they infect.
The nucleic acid can be: RNA or DNA; single stranded or
double stranded.

13. VIRAL STRUCTURE

14. Herpesviridae
1) Herpes zoster: Chicken
pox
2) There are two main
strains of the Herpes
virus: HSV-1 and HSV-
2. Either of these
strains can cause genital
herpes
3) VHH-4: Epstein-Barr:
the “kiss infection”

15. Herpesviridae
DNA double stranded- dsDNA

16. Retroviridae
- HIV  AIDS
- Single stranded RNA
- Retrovirus: Reverse
transcriptase. Its ARN
can be turned into DNA
when it inffects a cell.

17. RETROVIRIDAE- HIV-AIDS

18. Genus Saccha- Amoeba Plasmo- Parame- Euglena Chlorella
romyces dium cium
Nutrition Heterotro Heterotro Heterotro Heterotro Heterotro Autotroph
phic: feed phic: feed phic: feed phic: feed phic and ic: they
on glucose on smaller parasiticall on smaller autotrophi possess
and other organisms y on red organisms c: they chloroplas
organic and blood cells and possess ts and
compoun detritus by detritus chloroplas synthesize
ds by digesting by ts and organic
absorbed endocytos the endocytos take compoun
from their is hemoglobi is organic ds by
surroundi n matter by photosynt
ngs endocytos hesis
is
Locomotio Non- Move by a Some Move by Move by Non-
n motile flow of stages in beating beating motile
cytoplasm the life their cilia their
to form cycle can rhytmicall flagellum
outgrowth glide over y
s surfaces
Cell wall Made of absent absent absent absent Made of
chitin cellulose

19. The Nitrogen cycle
• Microbes occupy a number of niches in ecosystems:
as saprotrophs (decomposers) they release nutrients
trapped in detritus and make it available to
ecosystems. Cyanobacteria (blue-green algae) and
protocists such as algae Euglena are photosynthetic
and act as producers
• The bacteria Rhizobium and Azotobacter can fix
nitrogen and convert it to a form that living things
can use.

20. • Bacteria such as Nitrobacter and Nitrosomonas can
use inorganic chemicals as energy sources. They are
known as chemoautotrophs.
• Nitrogen would quickly become a limiting factor for
ecosystems if it were not for the bacteria involved in
the nitrogen cycle.
• In agriculture, soil nitrogen is often supplemented
with fertilizer. Fertilizer can be industrially produced
through the Haber process, which produces
ammonia from atmospheric nitrogen.
Alternatively, other sources such as manure from
livestock production can be used.

21. NITROGEN CYCLE: showing the roles of
Rhizobium, Azotobacter, Nitrosomas, Nitrobacter and Pseudomonas

22. Sewage and sewage treatment
• The consequence of not treating sewage and
allowing it to flow in to watercourses would be
nutrient enrichment, or eutrophication.
• This favours algal blooms. When the mats of algae
die, it leads to a loss o oxygen, because of bacterial
activity on the dead organic matter. This is called
biological oxygen demand
*Sewage: water-carried wastes
Eutrophication: is the addition of artificial or natural substances, such as
nitrates or phosphates, through fertilizers or sewage to an aquatic
environment.

23. • Many sewage treatment plants make use of biofilms. A
trickling filter system has a rock bed that can be up to 2
metres deep. The rocks are colonized by a biofilm of aerobic
bacteria. Sewage water is sprayed onto rocks. The process of
spraying adds oxygen to the sewage, which is necessary for
the aerobic bacteria to digest the sewage content.
• Reed-bed systems make use of a range of ecological
community members to treat sweage. Artificial oxygenation
supports aerobic bacteria in lowering the biological oxygen
demand (BOD) of the sewage. Plants such as reeds extract
nitrogen from the water, small animals such as rotifers and
other filter-feeding vertebrates extract particles

24. Sewage

25. Sewage treatment plant

26. Methane generation
• Three different communities of anaerobic microbes are
required.
1) The first group converts the raw organic waste into a mixture
of organic acids: alcohol, hydrogen and carbon dioxide.
2) The second group uses the organic acids and alcohol from
the first stage to produce acetate, carbon dioxide and
hydrogen.
These first two communities are Eubacteria
3) The last group are Archea called methanogens. They produce
methane by one of these reactions:
CO2 + 4H2  CH4 + 2H2O (reduction)
CH3COOH  CH4 + CO2 (splitting acetate)

27. Methane generator

28. Gene therapy
• Some inherited diseases are caused by a defective
gene, that results in the lack of particular enzyme or
protein. Cystic fibrosis is one such disease. It is
caused by th lack of cystic fibrosis transmembrane
protein (CFTP). This protein normally transports
chloride ions out of cells and into mucus. The
chloride ins draws water out of the cells and make
mucus watery. Cystic fibrosis patients suffer fro thick
mucus, which builds up in the airways.

29. • Gene therqapy may offer a cure for inherited
diseases like cystic fibrosis. In gene therapy,
working copies of the defective gene are
inserted into a person’s genome. To do this, a
gene delivery system or vector is needed.
• It’s very normal to use viruses as vectors.
• The viral genome is altered so that the
particles are not virulent. The therapeutic
gene is then inserted into the virus. The viral
DNA is then inserted into the genome.

30. • However therapeutic genes are not passed from one
generation to the other, so treatment has to be
repeated.
• A challenge of using viruses as vectors is that the
host may develop immunity to teh virus.
• The treatments may be of two types:
a) Using somatic cells (body cells)
b) Using egg cells. Injection of therapeutic genes into
egg cells. The missing gene would be expressed in
all cells of the organism. It is called  Germ line
therapy

31. Using Saccharomyces in food
production
• Saccharomyces cerevisiae is a fungus that is
widely used in biotechnology. Alcoholic
fermentation produces alcohol and CO2.Its
fermentation reactions are used in the
production of beer, wine and bread.

32. 1) In wine production, Saccharomyces occurs naturally
on the surface of grapes. Crushed grapes are
allowed to ferment in the presence of the yeast. If
the grape skins are left within the fermentation
vessel during this time, the alcohol that develops
will be a red wine.
2) In beer production, barely grains are allowed to
germinate so taht some starch is converted to
maltose. The grains are then heated to denature
the amylase and further processed so that the
sugars are washed out of the,. The resulting
solution has Saccharomyces added and is allowed
to ferment.

33. 3) In bread productionm Saccharomyces is added as an
ibgredient to the dough. The dough is left to rise,
which means the yeast is allowed to operate on the
sugars in the flour or on added sugars.
The CO2 produced as a result of fermentation caused
the bread to rise.
To make soy sauce a salted mixture of crushed
soybeans and wheat is treated with the fungus
Aspergillus, which breaks down the starch in the
substrate of glucose. This is the fermented in the
presence of salt, by other microbes to produce soy
sauce

34. Saccharomyces

35. Food preservation and food poisoning
• Food preservation involves controlling the growth of
microorganisms. High salt or high sucrose
concentrations provide osmotic inhibition.
• Pickling is a process that often involves storing food
in stalt or vinegar solution and allowing anaerobic
respiration to occur. The inorganic acids produced,
such as lactic acid, inhibit growth of other kinds of
microbes.

36. • Food poisoning is an illnes caused by eating
foods containing toxins produced by
pathogens. Poor preparation of foods such as
poultry or other meat products is often the
source of pathogens.
EXAMPLES:
1) Clostridium botulinum is a rod-shaped bacterium that produces
neurotixins known as botulinum neurotoxins that cause muscular
paralysis.
Botulism poisoning can occur due to improperly preserved or home-canned,
low-acid food that was not processed using correct preservation times
and/or pressure.

37. Clostridium botulinum

38. 2) Certain strains of Staphylococcus aureus can
produce food poisoning. If food is contaminated with
these bacteria and stored at temperatures above
4ºC, they multiply and produce harmful toxins
(enterotoxins). Many foods can be contaminated,
including poultry, meat, eggs, salads and a wide
variety of processed foods.
The symptoms caused by the toxins are nausea,
vomiting and diarrhoea and these develop within a
few hours.
Treatment does not involve killing the bacteria, but
instead replacing substances lost in diarrhoea.
Oral rehydratation fluids are usually given.

39. Staphylococcus aureus

40. Bioremediation *
• Bioremediation is the use of microbes, fungi, plants
or enzymes to remove environmental contaminants
from water or soil.
1 )The bacterium Dehalococcoides ethenogenes has
been used to break down chlorinated solvents in soil.
2) The bacterium Geobacter sulfurreducens uses
uranium as an electron acceptor converting it from
soluble to insoluble form, which allows the uranium
to settle out and be collected.

41. 3) Some members of the genus Pseudomonas can use
crude oil for energy. They also require substances
such as potassium and urea as nutrients. These are
often sprayed on to an spill to aid the bacteria in
their work.
Bacteria are very useful in bioremediation because they can
multiply very quickly by binary fission and they are very varied
in their metabolism. Bacteria carry out a wider range of
chemical reactions, especially inorganic reactions, than any
other group of organisms. There is often a species of
bacterium that will perform the necessary reaction in a
bioremediation process.

42. Controlling Microbial growth
Because microbes can cause disease and food
spoilage, a number of methods have been
devised to control their growth.
1) EXPOSITION TO GAMMA RADIATION:
This method has the advantage of destroying
nearly all microbes as well as insects and other
pests.
It is sometimes used with fruit; but some consumers
are reluctant to consume radiated food.

43. 2) PASTERIZATION:
Is a method of treating food by heating it to
certain temperature to kill pathogenic organisms
but not to harm the flavour or quality of the
food.
-Milk  60°C / 30’
-Flash pasteurization 70°C/ 15´´, coolong -
10°C and storage at lower temperatures.
- Used in beer, wine, fruit juces, cheese and egg
products.
- Its main disadvantage is that it does not kill
all microbes.

44. 3) ANTISEPTICS
Are chemical substances that kill or prevent the
growth of microbes on living surfaces such as
the skin and wounds.
Most common:
- Iodine
- Hydrogen peroxyde
- Isopropyl alcohol.
They may be toxic when being ingested, that’s
why they are not used in foods.

45. 4) DESINFECTANTS:
Are chemical substances taht kill or prevent the
growth of microbes on non-living surfaces.
- Used on food preparation surfaces and
medical equipment.
- They are too toxic to be used on living surfaces
or in foods

46. 5) ANTIBIOTICS:

47. PANDEMICS
An EPIDEMIC is a widespread outbreak of an
infectious disease, in which many people are
infected at the same time.
A PANDEMIC is a very widespread epidemic that
affects a large geographic area and crosses
international boundaries.

48. 1) A recent pandemic began in 2009, whrn a
new strain of influenza virus appeared, called
H1N1, but commonly referred to as swine flu.
• It probably appeared in Asia and affected pigs
only, but then it got to mexico and infected
humans.
• It spread throughout the world by human-to-
human transmission.

49. 2) Malaria
Is caused by the transmissiom of an unicellular
eukaryote.
In humans:
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
They affect red blodd cells and are transmited
by a vector: the mosquito from the gender
Anopheles.

50. P. Malariae cycle

51. Metabolism of microbes *
• Microbes can be classified by their mode of
nutrition, including their sources of energy
and of carbon.
1) Photoautotrophs: obtain energy from light,
source of carbon it’s inorganic. Ex:
Cyanobacteria
2) Chemoautotroph: source of energy, inorganic
chemicals (H2S), source of carbon inoganic.
Ex: Nitrobacter

52. 3) Photoheterotroph: source of energy is light,
source of carbon is organic. Ex: Rhodobacter.
4) Chemoheterotroph: Source of energy, organic
compounds; source of carbon, organic
compounds. Ex: Mycobacterium tuberculosis.

53. Microbes and disease
• Pathogenic microbes obtain nutrients through
parasitism. To do this they need to gain entry
to their hosts. Pathogens are transmitted in a
number of ways:
1) Direct contact between the infected and
uninfected person of between a surface and
the new host. Example: Norwalk virus
2) Cuts: Clastridium tetani

54. 3) Droplets: coming in contact with droplets
from an infected person such as through a
cough or sneezing. Ex: Influenza virus
4) Ingesting contaminated food or water. Ex:
Salmonella enterica.
5) Insects acting as vectors. Ex: West Nile virus
6) Sexually transmitted diseases. Ex: Chlamydia.
After a pathogen enters the body, a disease can
be caused if the microbe colonizes a tissue.
Bacteria such as Streptococi release digestive
enzymes that allow them to invade tissues.

55. Most bacterial infections are found around cells,
but some actually infect cells intracellularly, such
as Rickettsia and Clamydia.

56. Influenza
• Flu is caused by a virus.
• The virus is spread in droplets, such as those
released by an infected person when they
cough or sneeze.
• When the viruses are inhaled, they bind to the
surface of the epithelial cells in the respiratory
system. They are brought inside through the
cell’s own endocytosis mechanism.

57. Influenza life cycle

58. • Influenza is a single stranded enveloped RNA virus.
• Once inside the cell, the genetic material and
accesory proteins are uncoated and the viral
molecules enter the nucleus.
• The viral enzyme RNA- dependent RNA transcriptase
begins making complementary copies of the viral
RNA.
• The viral RNA is either exported into the cytoplams
and translated, or it remains in the nucleus.
• Some newly synthesized viral proteins are inserted in
the cell membrane and some are transported back
into the nucleus to assemble the new viral proteins.