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In natural environment, microbial cells will
almost always be in mixed cultured. They have
to interact each other, but these interaction
are limited by the potential of each cell.
Each species of the environmental microbe
has specific potential and some of them are
potential to produce useful industrial products.
The microorganisms encompass the three
groups:
Viruses, Prokaryotes, and Eukaryotes
Other microbiologists claim three Kingdoms of
five Kingdoms of cellular life are
microorganisms, namely:
Monera : bacteria (procaryotae) and blue
green
algae
Protista
: protozoa, eukaryotic algae, slime
moulds and flagellated fungi
Fungi
: non-flagellated fungi
It is not having a
cell structure
 It is dependent on
its host’s metabolic
machinery
 Its structure of
nucleic acid, DNA
or RNA, is
surrounded by
protein and
sometimes an outer
lipid-rich envelope
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Purple bacteria and the green bacteria
 Gliding bacteria
 Sheathed bacteria
 Spirochaetes
 Spiral and curve bacteria
 Gram-negative aerobic rods and cocci
 Gram-negative facultative anaerobic rods
 Gram-negative anaerobic bacteria
 Methane producing bacteria
 Gram-positive cocci
 Gram-positive endospore-forming rods and cocci
 Group of Lactobacillaceae
 Actinomycetes
 Rickettsias
 Mycoplasmas
 Cyanophyceae or Cyanobacteria
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The students are divided into several
groups and each group…
…discuss these grouping of prokaryote
microorganisms (the bacteria) and the
beneficial of them in industrial purposes.
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Bacteria are unicellular, most ca. 0.5-1.0 x 2.0-10 µm in
size.
They can be motile or non-motile
Cytoplasmic materials are enclosed in a rigid wall on
the surface and a membrane beneath the wall, and
they are immobile.
The membrane contains energy generating
components.
The genetic materials (structural and plasmid DNA) are
circular, not enclosed in nuclear membrane, and do
not contain basic protein such as histones.
Cell division is by binary fission.
Can also have flagella, capsules, surface layer protein,
and pili for specific function.
Some also form endospores (one per cell)
Gram-positive cells or Gram-negative cells
If we look at the shape and size, called
morphology, it is more simple to use them
for grouping the bacteria. The most
common shapes are rod-like, bacillus
(plural: bacilli), and sperichal, coccus
(plural: cocci)
The rods form vary from short rods (almost
look like cocci) to very long filaments. Also
form spiral and corkscrew, oval (coccoid),
comma, and branch structure.
Eukaryotic cells:
 are generally much larger than prokaryotic cells
 have rigid cell walls and thin plasma membranes
(contain sterol)
 the cell wall does not have mucopeptide and is
composed of carbohydrates
 the cytoplasm is mobile (streaming) and contain
organelles
 the DNA is linear (chromosomes), contains histones,
and is enclosed in a nuclear membrane.
The eukaryotic microorganisms are:
Fungi
Algae
Protozoa
Yeasts – unicellular
Molds – multicellular
Molds
 are non-motile, filamentous and branches
 the cell wall is composed of cellulose, chitin, or
both
 are composed of hyphae (large number of
filaments), an aggregate of hyphae called
mycellium.
 a hyphae can be vegetative or reproductive,
the reproductive hyphae usually extend and
form exospores, either free (conidia) or in sack
(sporangium). Shape, size and color of spores
are used for taxonomic classification.
Yeast
 the cells are oval, spherical, or elongated (5-
30 x 2-10 µm), non-motile.
 the cell wall contains polysaccharides
(glycans), protein and lipids.
 the cytoplasm has a finely granular
appearance for ribosomes and organelles.
 the nucleus is well defined with nuclear
membrane
The algae are photosynthetic eukaryotic
microorganisms.
 The major primary producers in the sea
and in lakes, but are also found in the
surface layer of soil.
 Many can live heterotrophically.
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The algae have been classified traditionally by pigmentation and
life cycle:
› Rhodophyceae, the red algae: marrine, multicellular,
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immotile, some unicellular
Chlorophyceae: many planktonic species, freshwater and
marine, motil by flagella,multicellular.
Prasinophyceae: unicellular planctonic flagellated organisms,
marine.
Euglenophyceae: unicells, motile by single flagellum,
common in nutrition rich freshwater pools, also found in the
sea and in the soil.
Bacillarophyceae, diatoms: in mcroplankton of sea and
lakes, motile.
Dinophyceae, dinoflagellates: in microplankton of seas and
lake s, motile, some are non photosynthetic.
Crysophyceae: found in freshwater, also the marine
silicoflagellates, biflagellate cells.
Haptophyceae: biflagellate planktonic algae, in marine,
blooms of this species can give the sea a milky appearance.
Cryptophyceae: unicellular flagellates found as minor
components of plankton.
algae… classified traditionally…:
–Xanthophyceae: multicellular, but few unicellular in plankton
and soil.
–Eustigmatophyceae: unicellular, in freshwater, sometime found
in soil.
Among aquatic microorganisms microalgae
are a very interesting source of a wide range
of compounds. They do not only have the
capacity to produce high-value compounds,
but also the ability to do it using only sunlight,
carbon dioxide and sea water.
Peptides and protein: lectins (glycoprotein)
have proved to be useful for clinical
diagnosis and other health application. Red
algae (Bryothamnion triquetrum, Solieria
robusta, Ceratodiction spongiosum)
 -carotene/canthaxanthin and astaxanthin:
green-algae, Haematococcus pluvialis.
 Seaweed polysaccharides
 Lipid – polyunsaturated fatty acid
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 Exhibit a very wide range of form and way of life.
 Many are predators on bacteria, fungi, algae, yeast,
or other protozoa, while some others are parasitic in
animals.
 Sarcomastigophora: the flagellated cells and
amoeboid protozoa, some are human pathogens
such as Trypanosoma brucei in the bloodstream, and
Entamoeba histolytica in the gut. Some flagellates
are symbionts in termite guts.
 Ciliphora: includes the familiar ciliates, Tetrahymena
and Paramecium. Vorticella species are very
important in sewage treatment processes.
 Sporozoa: totally endoparasitic in animals or man,
Plasmodium cause malaria.
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Factors inherent to the media/substrate
of the growth are considered intrinsic
factors which may stimulate or retard the
growth of microbial, including:
› pH (acidity)
› Water Activity (moisture)
› Oxidation-reduction potential (oxygen or
ionic)
› Nutrition (food)
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Environment factors that influence
microbial growth are considered extrinsic
factors, such as:
› Temperature
 Each species of microbe has an optimal temperature of
growth
 Temperature regulate the expression of gene
 The growth temperature can also influence a cell’s
thermal sensitivity.
› Gas composition
 It relates to the oxygen concentration. Many microbes
are inhibited in low concentration or without of oxygen,
but some may grow even though in the absent of
oxygen.
 It is applied in food preservation using controlled or
modified atmosphere storage.
Four phase of microbial growth:
Log
Total
mikroba
Fase lag
Fase
logaritmik
Fase stasioner
Waktu
Fase
kematian
During the log, or exponential, growth
phase microbes (bacteria) reproduce by
binary fision. Thus, during this phase, firstorder reaction can be used to describe the
change in cell number
 The number of microbes (N) at any time is
directly proportional to the initial number of
microbes (No)
 The microbiologists frequently use td to
describe growth rates of microbes and µ to
describe specific growth rates
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The killing of microbes by energy input,
acid, bacteriocin, and other lethal agents is
also governed by first-order kinetics
 By this kinetic reaction, it can be predicted
the number of microbes (viable cells)
remaining after treatment, such as in
sterilization process.
 In microbiology, D value (amount of time
required to reduce No by 90%) is the most
frequently used as kinetic constant. D
values are inversely proportional to the rate
constant, k, for a given temperature.
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Growtha
Thermal inactivationb
Iradiationc
N = Noeµt
N = Noe-kt
N = Noe-D/Do
2.3log(N/No) = µ∆t
2.3log(N/No) = -(k∆t)
∆t = [2.3 log(N/No)]/µ
∆t = -[2.3 log(N/No)]/k
td = 0.693/µ
D = 2.3/k
aN,
cell number (cfu/g); No, initial cell number (cfu/g); t, time (h); µ, specific growth rate (h-1); td,
doubling time (h); bk, rate constant (h-1); D, decimal reduction time (h); cDo, rate constant (h-1);
D, dose (Gy)
µ (h-1)
td (h)
Optimal conditions
2.3
0.3
Limited nutrients
0.20
3.46
Psychotroph, 5oC
0.023
30
0.1 – 0.3
6.9 – 20
Organism
Bacteria
Molds, optimal
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The availability of suitable nutrients is clearly a
major factor determining whether the microbes will
grow or not in a particular environment.
There are four useful ways to classify potential
nutrient mlocules:
› As esential, or useful but dispensable
› Used as building blocks for macromolecules, or as energy
sources, or as both
› As macronutrient required in large quantities, or as
micronutrients
› As macromolecules requiring breakdown before entry to
the cell, or small molecules readily entering as soluble
nutrients.
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The major elements of the cell are carbon,
hydrogen, oxygen, nitrogen, sulphur and
phosphorous.
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Carbon dioxide is utilized as sole carbon source
only by autotrophs. Carbohydrates are commonly
utilized as sources of carbon. Organic acids are
readily used directly as sources of carbon by most
microbes. Protein and their constituent organic
acids are utilized as carbon sources by proteolitic
microbes.
Nitrogen is abundant as gaseous dinitrogen, but
only few prokaryotic organisms and some of bluegreen algae can utilize it. Other sources of
nitrogen, such as nitrate, amonia, amino acids,
nucleotides, uric acid and urea, can also provide
cells’ requirements for nitrogen.
Some organisms can utilize hydrogen sulphide as
source of sulphur. Organic sulphur as amino acids
cysteine and methionine can also be used.
Probably all organisms can utilize soluble inorganic
phosphate.