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Topics: Enterobacteria, Enterobacteriaceae, Escherichia coli Pages: 23 (980 words) Published: June 22, 2015
Microbiology Unknown Lab

0.1%
dextrose

TSI agar
(a) Red/red (no sugar
fermentation)

(b) Control
(c) Red/yellow (Glucose
fermented but lactose and
sucrose not fermented)

(d) Yellow/yellow (Glucose
fermented. Lactose and/or
sucrose fermented)

(e) Red/yellow with H2S

Triple Sugar Iron Agar

1.0%
sucrose

A

1.0%
lactose

B

C

D

E

Penol Red broths
A

B

C

D

E

A (acid with gas)…..B (acid)……C (uninoculated control)……D (no recation)… …E (alkaline reaction)

O-F tests

Control

E. coli
Fermenter

Pseudomonas
Oxidizer

Alcaligenes
Nonsaccharolytic

Motility Test

Decarboxylation
uninoculated
Positive
Negative

Gelatin Hydrolysis

Simmons Citrate
A

B

C

A: Positive…Enterobacter
B: Negative…E. coli
C: Control-uninoculated

Phenylalanine Deaminase Test

neg

pos

Urea Hydrolysis
Positive
Negative

uninoculated

Methyl Red Test

A

A: Positive (E. coli)

B

B: Negative (Enterobacter aerogenes)

Voges Proskauer Test
A

A: Negative (E. coli)

B

B: Positive (Enterobacter aerogenes)

Indole Test
Negative

-

Positive

+

Catalase Test

+

Positive

Negative

GRAM
STAIN

General Microbiology (BIOL 187) Laboratory Report (Unknown Identification)  
Page 1: Cover page
Include your name, the unknown number and you final Genus and species identification  
Page 2: Test listing
I want a (+) / (-) listing of each test in a vertical, easily scanned format Page 3: Discussion section
Detail, in complete sentences, why your results justify your identification and rule out other possibilities.  
Page 4: About My Microbe section
Research your microbe and give me a several paragraphs about your microbe. (Don't copy word-for-word from your textbook---This will be frowned upon!)  
Page 5: Dichotomous key
Create a neat dichotomous key, which results in the correct separation of all 8 possible unknowns. This key should be legible and sized to occupy a complete sheet of paper (nothing microscopic is acceptable here)  

Page 6:Lab handout where you recorded your initial results
Include the handout from lab where your recorded your data as you read the test reactions.  
Grading:
20 pts.
Correct Identification
10 pts.
Discussion section
7 pts.
"About my microbe section"
8 pts.
Dichotomous key
5 pts.
Neatness, accuracy and completeness of report
50 points total

Differential Identification of Enterobacteriaceae by Biochemical Tests. Test

Escherichia coli

Shigella flexneri

Salmonella
enteritidis

Citrobacter
freundi

Enterobacter
cloacae

Enterobacter
aerogenes

Proteus
vulgaris

Proteus
mirabilis

+

- or +

-

-

-

-

+

-

Methyl
Red

+

+

+

+

-

-

+

+

VogesProskauer

-

-

-

-

+

+

-

- or +

Simmons
Citrate

-

-

+ or -

+

+

+

- or +

+ or -

Hydrogen
Sulfide

-

-

+

+ or -

-

-

+

+

-

-

-

+ or -

+ or -

-

+

+

Indol

Urease
Motility

How do I interpret the table above??
+
+ or - or +
(+)
d

+ or -

-

+

+

+

+

+

+

Gelatin
Hydrolysis

-

-

-

-

- or (+)

- or (+)

+

+

Lysine
decarboxylase

+ or -
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