The Effect of Saliva on Bacteria

beefzoologistBiotechnology

Feb 21, 2013 (4 years and 3 months ago)

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Does saliva have an effect on bacteria?


If so, what is this effect?


The reason I wanted to do this project was
because I wanted another opportunity to
work with bacteria. I find it very interesting.
Also, I have always heard people say “a dog’s
mouth is cleaner than a human’s.” By testing
the saliva’s effect on bacteria, I tested the
cleanliness of the mouth.



Gram negative


Motile


Facultative anaerobe


Heterotrophic


Mixed acid
fermentation: lactate,
succinate
, ethanol,
carbon dioxide and
acetate


Conjugation,
transformation and
transduction


Gram positive


Facultative anaerobe


Endospore

forming


From maltose, glucose
and
salicin

fermentation,
acid is made.


Two types of food
poisoning


E. coli


B. cereus


Gram positive


Nonmotile


Metabolizes sucrose to
lactic acid


Beta
-
hemolytic


Allowed to grip to
teeth because of
receptors


Found mainly on teeth



Gram positive


Nonmotile


Facultative anaerobe


Grows on plastic
objects in body


Ferments maltose, not
xylose, sucrose or
trehelose.


S. mutans


S. epidermidis


Saliva


98% water


Two main enzymes:


Lysozyme: antibacterial


Amylase: digestion


Oral Hygiene: teeth and mouth; residue, particles,
and epithelial tissue.




Amylase


Enzyme


breaks down carbs from
polysaccharides to
disaccarides




Lysozyme


Enzyme


“lyses” certain bacteria;
breaks down cell walls;
rinses away energy sources



If varied types of saliva are used on bacteria,
then human saliva will have the most
inhibitory effect on the bacteria.


Bacteria:
E. coli, B.
cereus, S. mutans
and
S. epidermidis


Amylase


Lysozyme



Additional Materials


Blank disks


Plates of agar


Innoculating loop


Autoclave


Matches


Incubator


Disposable gloves


Safety goggles


Saliva will be extracted


2 tabs will be soaked in each saliva type


2 tabs will be soaked in amylase


2 tabs will be soaked in water


2 tabs will remain blank


The
E. coli

and
B. cereus

will be plated using sterile
technique


The tabs will then be added to the bacterial plates


The plates will be sealed and stored at 37 degrees Celsius


Bacterial growth will be observed over the period of 3 days



The zone of inhibition will be measured



Saliva will be extracted


2 tabs will be soaked in each saliva type


2 tabs will be soaked in water


2 tabs will remain blank


The
S.
mutans

and
S.
epidermidis

will be plated using
sterile technique


The tabs will then be added to the bacterial plates


The plates will be sealed and stored at 37 degrees
Celsius


Bacterial growth will be observed over the period of 3
days



The zone of inhibition will be measured



I furthered my research and discovered that the
enzyme
lysozyme

is the enzyme in saliva that breaks
down bacteria.


2 tabs will be soaked in water


2 tabs will remain blank


All four types of bacteria will be plated again using sterile
technique.


Plates will be sealed and stored and 37 degrees Celsius


Bacterial growth will be observed over a period of three
days


The zone will be measured on the third day


My hypothesis stated that if three different
types of saliva were used to inhibit bacterial
growth, then human saliva would be the
most effective in doing so.


This hypothesis was not supported by the
data because saliva’s inhibitory effect was
equivalent to that of water.


What went wrong


A fungus grew on a few of the plates. It possibly
came from the air or careless sterile technique.


Improvements


More careful with sterile technique, the bacteria
and tabs.


National Center for Biotechnology Information
.
N.p
., Oct. 1999. Web.
30 Nov.



2009. <http://www.ncbi.nlm.nih.gov/pubmed/10553245>.


Leboffe
, Michael J., and Burton E. Pierce.

A Photographic Atlas for
the



Microbiology Laboratory
. Englewood: Morton Publishing ,
n.d
.
Print.


Sherwood,
Lauralee
.

Human Physiology
.
N.p
.: Thomson,
n.d
. Print.


Tenovuo

,
Jorma
. "Antimicrobial function of human saliva
-

how
important



is it for oral health?"

Informahealthcare.com
.
N.p
.,
n.d
. Web. 30
Nov.



2009. <http://informahealthcare.com/doi/abs/10.1080/



000163598428400?cookieSet=1&journalCode=ode>.