Help an undergraduate student

The_Warrior almahdi at magma.ca
Sun Mar 6 19:19:07 EST 2005

This is our final proposal, what do you guys think of it?

Reductions in Light Production of Bioluminescent Bacteria Resulting From
Metabolic Changes Caused by Aquatic Pollutants


Bioluminescent bacteria can be found in symbiotic relationships with a
variety of fish. These bacteria are capable of producing light, and often
fish are found to take advantage of this. These light producing bacteria can
be used by fish for a variety of reasons that may include attracting prey,
startling predators, or reproduction.

The production of light by bioluminescent species of bacteria is
metabolically linked. Decreased metabolism results in decreased production
of bioluminescent compounds.


There will be two purposes for this experiment.

1)      To isolate and identify (to at least the genera level)
bioluminescent bacteria found in the scales of fish.

2)      To determine the effect (if any) that a common environmental
pollutant (such as PNP or DDT) will have on the metabolic activity of the
isolated bioluminescent bacteria.



A fresh, untreated sample of fish with the skin intact will be collected.

The fish sample will be scraped with a sterile needle, and the sample will
be plated onto artificial salt water (ASW) growth medium. This medium will
be stored at 4oC for several days.

The growth medium will be examined in the dark for “glowing” colonies, and
these will be streaked-to-purity on another ASW plate.

After isolating colonies of the bacteria, they will be gram stained and
analyzed with a Biolog plate to rapidly determine the genera of the
organism. Many bioluminescent bacteria are of the Vibrio genera.

(This process would be ideal for the practical experience of isolation,
however, if a sample of Vibrio sp. bacteria is available in the lab and the
bacteria cannot be properly isolated from fish, then access to a prepared
sample in the lab would save time.)


Fish sample

ASW agar

Gram staining chemicals (crystal violet, iodine, 95% ethanol, safranin)

Biolog Rapid Identification Plate

Testing the Effects of an Aquatic Pollutant on Metabolism

The isolated bacteria will be stored in a broth tube of ASW.

A number of ASW will be used to determine the metabolic impact of pollutants
on the isolated bacteria. Several plates containing a range of environmental
pollutants (such as PNP or DDT) over several orders of magnitude (eg. 10-1
to 10-10) will be used to observe the effects on metabolism. Control plates
will be made containing only ASW medium.

(We are not positive which compounds we will have access to, and it is
possible that we may do more than one pollutant depending on time and
availability of the chemicals. We are hoping for some assistance with the
range of concentrations that we should use for each of the chemicals.)

Since production of bioluminescent compounds is metabolically linked, the
impact of the toxic compound will be observed spectrophotometrically.

(We are not fully sure how to set this up with the spectrophotometer, so we
will need some help with this method.)

The control plates will be used to determine a baseline level of light
production by the bacteria.


~20-25 petri dishes

Environmental pollutants, such as DDT or PNP



Our prediction is that bioluminescence will decrease in relation to the
concentration of the toxic compound. This relationship will be graphed out
as intensity of light vs. concentration.

"The_Warrior" <almahdi at magma.ca> wrote in message
news:sYadnY5g8ohSFbvfRVn-pg at magma.ca...
> Hello every one, I'm a biology student in a University, and I truelly need
> your assistance in choosing a good topic for an undergraduate microbiology
> project. We tried isolating and quantitatively analyzing bacteria from
> common uncooked food products found in a grocery store such as chicken
> fish, beef, and yogurt as a control.
> Then, to generally identify any bacteria isolated from the food samples
> to test the antibiotic resistance spectrum of the isolated bacteria. After
> these steps, we would follow few microbiology techniques that we learned
> the labratory which would help us better analyze the metabolic properties
> the bacteria. Unfortunately we were told by the instructor that this topic
> is not challenging at all because it had been done so many times.
> Some of the techniques we thought of doing is using
> The following equipment:
> Incubator (already present in lab)
> Centrifuge (already present in lab)
> Blender
> Sterile Water (or MMA)
> Nutritional Agar (NA) and Petri dishes (around 20-30 dishes)
> Sterile test tubes (For serial dilutions) – approximately 20
> Cell lysing solution (EDTA or any other sufficient to lyse bacteria)
> Antibiotic filter discs (Generic ones such as Kanamycin, Streptomycin,
> Penicillin)
> Test tube vortexer
> Gram staining reagents (Crystal violet, Gram’s iodine, safranin, 95%
> ethanol, slide)
> Microscope
> Can anyone help my partner and I in choosing a good topic to do for an
> experiment?
> We either can do literature based project or experimental based project.
> really prefer the experemental based projects because our course is an
> expermental microbiology course, so can you help us?
> I'll wait for your reply
> Thank you!!

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