1. No category

USING BACTERIA MORPHOLOGY
CHARACTERISTICS TO STUDY BACTERIAL
DIVERSITY.
092404 EMJT
By Ellie Masserrat
Pian Lu
John Taucher
Bacteria…?
Leptospira, causes serious disease in livestock

Bacteria are often viewed as the cause of diseases in humans and animals.

Some bacteria are useful, for example certain bacteria aids in digestion.

Bacteria make up the base of the food web in many environments.

Bacteria are of such immense importance because of their extreme flexibility,
capacity for rapid growth and reproduction, and great age.

They can be photosynthetic, using light, or chemosynthetic, using inorganic
chemicals as the source of energy, but most are heterotrophic, absorbing
nutrients from the environment.
Background Information
Prokaryotes

Prokaryotes represent two domains, bacteria
and archaea.

Archaea live in Earth’s extreme environments.

Bacteria are the most abundant and diversified
organisms on Earth.
Bacterial Structure

Biochemical processes that
normally occur in a chloroplast
or mitochondrian of eukaryotes
will take place in the inner
membrane of prokaryotes.

Bacterial DNA is circular and
arrayed in a region of the cell
known as the nucleotide .

Scattered within bacteria’s inner
membrane are numerous small
loops of DNA known as
plasmids .
Structure



Some bacteria have
flagella with a different
microtubule structure than
the flagella of eukaryotes..
Ribosomes are the
structures in cells where
proteins are assembled.
Bacterial ribosomes have
different sized ribosomal
subunits than do
eukaryotes.
Bacteria Have One of Three
Cellular Shapes

Rods (bacilli)

Coccoid-Shaped

Spirilla
Reproduction

Prokaryotic cell division is
binary fission.
–
–
–
–
Single DNA molecule that first
replicates.
Attaches each copy to a
different part of the cell
membrane.
Cell begins to pull apart.
Following cytokinesis, there
are then two cells of identical
genetic composition.
Now…On to our experiment...

Purpose: Identify varieties of bacterial colonies and investigate
bacterial species diversity, by isolating, culturing, and analyzing
bacterial colonies, or species, that inhabit:







Air
Pond Water
Raw Chicken
Washed/Unwashed hands
Keyboard
Soil Sample
Hypothesis: Knowing that bacteria can thrive in almost anywhere
on our planet, we reason that all of the environments tested will
grow bacterial species. We further hypothesize that the thumb
print of the washed hand with the anti-bacterial soap, should
house less species than any others tested, because the anti-bacterial
soap should kill off all bacteria.
Methods

A
.

B.


C.

Figure 1.
Streak Plate Method. (a) Streak the
plate back and forth across top half of plate. (b)
Rotate plate a quarter turn counter clockwise and
streak top right quarter of plate. (c) Rotate plate a
quarter turn counter clockwise and streak top right
quarter of plate again.

For chicken, soil, pond water,
and keyboard samples, streak
the plate using the streak plate
method to isolate bacterial
colonies.
Leave agar plate open for air
sample.
For the unwashed hand gently
press thumb against agar.
Take washed hand and gently
press thumb against agar.
Wrap in Parafilm and incubate
the cultures for about one week
at 22 C.
Observe and Interpret Data
Results: Soil
SIZE
SHAPE
MARGIN
SURFACE
COLOR
4 mm
Irregular
Lobate
Wavy
Yellow/white
3 mm
Irregular
Lobate
Wrinkled
Brown/yellow
5 mm
Filamentous
Filamentous
Wrinkled
Green/white
2
1
3
Results: Pond Water
#
1
2
3
Size Shape
Margin
Surface Color
2 mm round
2 mm round
1 mm round
smooth
lobate
Smooth
Smooth
contoured
Smooth
2.
1.
3.
grey
beige
clear
Results: Raw Chicken
#
1
2
3
4
Size
2mm
3mm
1mm
2mm
Shape
Irregular
irregular
round
Irregular
Margin
lobate
lobate
Smooth
wavy
Surface
contoured
wrinkled
Smooth
contoured
Color
yellow/green
clear/white
Yellow/green
brown
1.
2.
4.
3.
Results: Air
#
1
2
3
4
5
6
7
Size
5 mm
5 mm
1 mm
3 mm
3mm
5 mm
8 mm
Shape
Irregular
Round
Irregular
Irregular
Irregular
round
irregular
1
Margin Surface
Color
Smooth Smooth Yellow/orange
smooth contoured Yellow/orange
Wavy contoured Yellow/white
Lobate wrinkled Yellow/brown
Lobate
smooth
White
Smooth Smooth White/yellow
lobate contoured White/yellow
2
1
7
3
6
4
5
5
Results: Washed Hand
1.
2.
Size
#
1 4 mm
2 1 mm
Shape
Margin
Surface
Irregular
filamentous
lobate
Smooth
filamentous smooth
Color
yellow
white
Results: Unwashed Hand
Size
#
1 2 mm
2 2 mm
3 1 mm
Shape
Margin
Surface Color
Irregular
round
round
lobate
Smooth
Smooth
smooth
smooth
Smooth
yellow
yellow
white
1
2
3
Results: Keyboard
Size
Shape
#
1 4 mm Irregular
2 1 mm filamentous
# Size
1 2 mm
2 1 mm
Shape
Irregular
round
Margin
lobate
smooth
Margin
Surface
lobate
Smooth
filamentous smooth
Color
yellow
white
Surface Color
wrinkled yellow
smooth greenish
2.
1.
Control

An unopened agar
nutrient plate, which
ruled out agar
contamination, had no
bacteria species
present.
Species vs. Environments
Number of Bacterial Species on Agar Plate
8
6
# of Species 4
2
0
Series1
Air Keyb Unw Was Pond Chic Soil
7
2
2
3
3
Environments
4
3
Conclusions/Observations



The results supported our hypothesis since
bacteria grew in all of our samples.
The results did not support our hypothesis
concerning the hand washed with anti-bacterial
soap since it did not house less species than the
other environments tested.
We were surprised to learn that the air not only
housed the most bacteria, but housed the most
bacterial diversity of species as well.
Further Investigations…



Further studies can be conducted by using TEM
microscopy, SEM microscopy, and gram staining,
to specifically identify what type of bacterial
species were present in each environment.
Research can also be conducted to figure out as to
why the unwashed hand contained more bacteria
than the washed hand.
Further research can be done to determine if any
of the bacteria found in our samples are harmful to
humans.
Questions to Ponder…
Do all bacteria grow at the same rate, and
what factors in the environment contribute
to determining their “carrying capacity?”
 What research can be done to determine
whether bacterial species and fungus
compete with each other for nutrients and
space in selected environments?

References
Coccoid-shaped Bacterium (causes skin infections), Enterococcus faecium
(SEM x33,370). This image is copyright Dennis Kunkel at
www.davidkunkel.com, used with permission.
 Morgan, I.G. and Brown Carter, M. E., Investigating Biology: A
Laboratory Manual for Biology. California: Benjamin/Cummings Publishing
Co., Inc. 1993.
 Rod-Shaped Bacterium, hemorrhagic E. coli, strain 0157:H7 (division)
(SEM x22,810). This image is copyright Dennis Kunkel at
www.davidkunkel.com, used with permission.
 Spirilla- shaped Bacterium (SEM x33,370). This image is copyright Dennis
Kunkel at www.davidkunkel.com , used with permission.

Serratia marcescens
Gram stain
Motility
Habitat
Pathogenicity:
Negative.
Motile.
Occurs naturally in soil and water as well as the
intestine.
Associated with urinary and respiratory tract infections,
endocarditis, wound infections, and eye infections.
Gram-positive and gram-negative bacteria
Difference Between Gram-Negative
and Gram-Positive Bacteria
Gram-Negative Bacteria
Gram-Positive Bacteria
More complex cell wall.
Simple cell wall.
Thin peptidoglycan celll wall layer.
Thick peptidoglycan celll wall layer.
Outer lipopolysaccharide wall layer.
No outer lipopolysaccharide wall layer.
Retain safranin.
Retain crystal violet/iodine.
Appear pink/red.
Appear blue/purple.
Antibiotic Sensitivity Test
Antibiotic Sensitivity Test
P10
TE30
Ø10
C30
E15
Ø14
Ø20
K30
NA30
Ø14
S10
Ø8
NB30
Hypothesis:
Kanamycin is one of the most sensitive
antibiotics because infections treated
include respiratory tract, urinary tract, skin,
soft- tissue and abdominal infections.
Prediction:
The size of the zone of inhibition is the
largest.
Results:
The size of the zone of inhibition is the 2nd
largest
Antibiotic Resistance
•
•
Some bacteria have developed resistance to antibiotics naturally.
Bacteria can become resistant to drugs in a number of ways.
- Mutation.
- Exchange genes with other bacteria.
- Resistant traits spread to future generations quickly because
of rapid reproducing.
Mechanism

Antibiotics kill or stop the growth of harmful bacteria.
Limitations


Reason unknown why S. marcescens is sensitive to certain
medications.
Further research needed.
Future Work

Develop new drugs to confront bacteria resistance.