Lab Report #1: Cultural Characteristics of Microorganisms
Shaylyn Robison
June 8, 2010
Course: Microbiology Lab BIOL 2065 Section 001
Instructor Annette Shelton
Class Time: W 10am-11:50 am
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Introduction
Purpose
To understand and determine the characteristics of microorganisms and to learn how to classify microorganisms into groups based of their characteristics.
Materials and Methods
24 hour nutrient broth cultures of:
Psedudomonas areruginose
Bacillus cereus
Micrococus luteus
Escherichia coli
Five nutrient agar plates
Five nutrient agar slants
Five nutrient broth tubes
Five nutrient gelatin tubes
Bunsen burner
72-96 hour Trypticase soy broth culture of: Mycobacterium smegatis
Glass marking pencil
Inoculating loop and needle
1.) Incoulate each labeled media with the correct culture in the following order:
A.
For agar plates: Using a sterile loop, prepare a streak plate inoculation with each of the cultures for the isolation of discrete colonies.
B.
For agar slants: Using a sterile needle, make a single-line streak of each cultures, starting at the bottom and drawing the needle up the center of the slanted agar surface.
C.
Broth: using a sterile loop, inoculate each organism into a tube of nutrient broth. To dislodge the inoculum, shake the loop a few times.
D.
Gelatin: Using a sterile needle, prepare a stab inoculation of each of the cultures provided.
2.) After inoculating each media, incubate all the cultures at 37 degrees Celsius for
24 to 48 hours.
Results
Each of the gelatin tube cultures showed growth (see figure 1). M. luteus had an infundibuliform, or funnel-shaped, liquefaction distribution. P. aeruginosa had liquefaction occur and had a pattern of straitform, where the top half of the medium is complete liquefied.
M. smegamtis did not have any liquefaction but the tube had growth on the top of the gelatin.
E. coli had a craterform distribution of liquefaction. B. cereus , like M. luteus , had a infundibuliform liquefaction distribution.
All of the nutrient agar plates had microorganism growth (see figure 2). The M. luteus agar plate had small colonies that were raised and circular. The pigmentation of M. luteus was yellow and the appearance of the margin was sharply defined and even. The P. aeruginosa plate had large colonies that were flat, circular and had a tan pigmentation.
The outer edge of the P. aeruginosa colonies had wavy indentations. The agar plate of M. smegmatis had small to medium, flat, and cream colored colonies. The colonies were of an irregular shape and had an outer edge that was undulate. The plate of E. coli had medium size colonies that were cream-colored and irregular shaped. The E. coli colonies had a convex elevation and an undulate margin. The agar plate of B. cereus had large colonies that were flat, irregular in size and were the color of cream. The edge of the colonies had marked indentations.
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Each agar slant cultures showed moderate to large growth (see figure 2). M. luteues had moderate, yellow growth that was beaded and had a dry, buttery consistency.
P. aeruginosa also had moderate sized, clear growth that had a form of effuse and a slimy consistency. M. smegmatis had a large amount of cream-colored growth that had an echinulate form and dry consistency. E. coli had moderate, clear/cream growth with a mucoid consistency and threadlike growth. B. cereus had large, clear/cream, threadlike growth that was also mucoid consistency.
Each nutrient broth cultures showed growth (see figure 4). The tube containing M. luteus had a sediment appearance of growth on the bottom of the tube. The tube contain
P. aeruginosa had a uniform fine turbidity distribution of growth. The M. smegmatis culture had a pellicle and sediment distribution of growth. The tube containing E. coli had a sediment and uniform fine turbidity distribution of growth. The B. cereus culture had a sediment distribution of growth.
Figure 1:
Gelatin
Cultures
Figure 2:
Agar Plates
Figure 3:
Agar Slant
Cultures
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Figure 4:
Broth Cultures
Discussion
The experiment was to “determine the cultural characteristics of microorganisms as an aid in identifying and classifying organisms into taxonomic groups (Rudolph 25).
The results that were the most exponential were the agar streak plates such as the B. cereus culture that showed large amounts of growth. The results that were harder to observe were the broth cultures. This could be due to the fact that microorganism may not live in certain environments as other microorganisms.
The significance of the experiment and the results is the ability to culture and isolate microorganisms and later on be able to use those results to classify microorganisms. In this experiment I learned vocabulary to classify organisms by their shape, color and the distribution of growth.
Extensions
This exercise could be applied to real world problems such as isolating a microbe that is infecting a water source or being able to test antibiotics against a certain microorganism. Culturing using different media is important to microbiology.
References
"Lab Report Example." Water/Wastewater Distance Learning Website . N.p., n.d. Web. 8
Jun 2010. <http://water.me.vccs.edu/report_example.htm>.
Rudolph, Dr. Jane. Symbiosis . Boston: Pearson Learning Solutions, 2010. 25-30. Print.
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