Fecal Coliform Bacteria Tests
Summary
TLDRThe video script details a scientific experiment to test for fecal coliform bacteria in various water samples using petri dishes with agar, a medium that supports bacterial growth. The experiment includes water from a pond in Riverside, California, fish tank water, tap water, and samples from the Santa Clara River, treated wastewater, bottled water, ocean water in Oxnard, reclaimed water from a pond, and a hiking trail in Whitney Canyon. Sterile pipettes are used to inoculate the agar with one milliliter of each water sample, which are then sealed and incubated. The results show that tap water, treated wastewater, and bottled water are negative for fecal coliform, while samples from the Santa Clara River, the reclaimed pond water, and the hiking trail in Whitney Canyon test positive, indicating the presence of bacteria from mammal feces. This serves as a cautionary tale about the importance of purifying or treating water from natural sources before consumption.
Takeaways
- 🧫 The purpose of the experiment is to check for fecal coliform bacteria in various water samples using petri dishes with agar.
- 🔬 Agar serves as a medium and food source for bacteria to grow and form colonies, with a special type turning pink to indicate fecal coliform bacteria.
- 📍 The water samples are sourced from different locations, including a pond in Riverside, California, a fish tank, tap water, and others.
- 🚿 A sterile pipette is used to take one milliliter of water from each sample to prevent contamination.
- 🚫 Petri dishes should be handled carefully to avoid leaving the lid off for too long, which can lead to airborne contamination.
- 🏷 Each petri dish is labeled according to its water source to keep track of the samples.
- 🛡️ Parafilm or a similar sealing material is used to seal the petri dishes, ensuring they remain closed to prevent contamination and pathogen exposure.
- 🔍 The results are observed by looking for the growth of colonies, specifically pink ones, which indicate the presence of fecal coliform bacteria.
- 🚰 Tap water showed no colonies, indicating the absence of fecal coliform bacteria, which is expected for treated water.
- 🐟 Fish tank water had bacterial growth but was negative for fecal coliform bacteria, suggesting the presence of beneficial bacteria for the tank's ecosystem.
- 🌊 Some water samples, like the one from the Santa Clara River, tested positive for fecal coliform bacteria, likely due to mammal feces runoff.
- ⛰️ Hiking trail water, such as from Whitney Canyon, tested positive for fecal coliform bacteria, emphasizing the need for water purification in outdoor activities.
Q & A
What is the purpose of using agar in the petri dishes?
-Agar serves as a growth medium or food source for bacteria, allowing them to grow and form visible colonies on the petri dishes.
Why are fecal coliform bacteria specifically tested in water samples?
-Fecal coliform bacteria are tested in water samples as indicators of possible sewage contamination and the presence of pathogens that could be harmful to human health.
What is the significance of the pink color of colonies in the testing process?
-The pink color of colonies indicates the presence of fecal coliform bacteria. The special agar used is formulated to turn pink when these specific bacteria grow, facilitating their identification.
Why is it important to use sterile pipettes when transferring water samples to the petri dishes?
-Using sterile pipettes prevents contamination of the samples with foreign bacteria or substances, ensuring the accuracy of the test results.
What is the role of parafilm in the experiment?
-Parafilm is used to seal the petri dishes after inoculation to prevent any airborne contaminants from entering the dishes and to maintain the sterility and integrity of the experimental environment.
What does a negative result indicate in these tests?
-A negative result indicates that no fecal coliform bacteria were detected in the sample, suggesting the water is free from contamination by mammal feces.
Why might tap water ideally show a negative result for fecal coliform presence?
-Tap water should ideally show a negative result as it is treated and purified to be free from harmful bacteria, making it safe for consumption and domestic use.
Why is it mentioned that fish tank water normally contains good bacteria?
-Fish tank water contains beneficial bacteria that help break down waste products in the aquarium, maintaining a balanced environment necessary for the health of the fish.
What could be the source of coliform bacteria in river water?
-Coliform bacteria in river water could come from runoff containing animal feces, such as from dogs, or from wild animals like coyotes living near the river.
Why is it advised not to drink water directly from creeks or streams while hiking?
-Drinking water directly from creeks or streams without treating it can be unsafe as it may contain coliform bacteria or other pathogens that can cause illness. It's advised to purify such water first by filtering, boiling, or using iodine drops.
Outlines
🔬 Preparing Petri Dishes for Water Sample Analysis
In this segment, the presenter demonstrates how to prepare Petri dishes with agar to test for fecal coliform bacteria in water samples. The process involves using a sterile pipette to transfer water from various sources, including a pond in Riverside, California, into the Petri dishes. Each sample is carefully added to the agar, swirled to ensure even coverage, and sealed with parafilm to prevent contamination. Labels are applied to identify the source of each sample. This meticulous procedure is crucial for obtaining accurate results in testing for the presence of coliform bacteria.
🔍 Analyzing Water Samples for Fecal Coliform Bacteria
The video continues with an analysis of the inoculated Petri dishes to determine the presence of fecal coliform bacteria. Results varied across different water sources: tap water showed no coliform growth, indicating good quality, while the fish tank and bottled water were also negative for coliforms but had beneficial or no bacteria respectively. In contrast, samples from Santa Clarita River and Oxnard ocean water showed signs of coliform colonies, suggesting fecal contamination possibly from nearby wildlife or runoff. The presenter emphasizes the importance of treating natural water before consumption to avoid health risks, showcasing positive coliform results in highly turbid river water and hiking trail water from Whitney Canyon.
Mindmap
Keywords
💡Inoculate
💡Petri Dish
💡Auger
💡Fecal Coliform
💡Sterile Pipette
💡Water Sample
💡Parafilm
💡Pathogens
💡Colonies
💡Treated Wastewater
💡Contamination
Highlights
Inoculating petri dishes with water samples to test for fecal coliform bacteria.
Using auger, a food source for bacteria, to grow colonies in petri dishes.
Special auger used grows pink colonies to identify fecal coliform bacteria.
Sterile techniques employed using pipettes and careful handling to prevent contamination.
Sampling water from various sources, including pond, fish tank, and tap water.
Sealing petri dishes with parafilm to prevent exposure and contamination.
No coliform bacteria found in tap water, indicating safe water quality.
Fish tank water tested negative for coliform but showed presence of beneficial bacteria.
Positive coliform test in river water likely due to animal waste runoff.
Treated wastewater from Gilbert, Arizona, showing no fecal coliform presence.
Bottled water confirmed negative for fecal coliform, with only clumps of agar present.
Ocean water in Oxnard tested positive for one colony of coliform bacteria.
Turbid water from Santa Clara River after rain tested strongly positive for fecal coliform.
Riverside pond water, from reclaimed water, tested positive for coliform due to nearby mammal activity.
Advice given on purifying natural water sources before consumption when hiking.
Transcripts
today I'm going to inoculate several
petri dishes to check for fecal coliform
bacteria and several water samples so
these petri dishes here have auger port
in them so let me turn on over and this
light yellow stuff is auger and it's a
medium a food source for bacteria to
grow and make colonies so we will check
our various water samples to see if they
have people coliform bacteria this
particular auger grows pink colonies to
check for bacteria it's a special one to
check for fecal coliform bacteria so
first I need a sterile pipette and I
need a water sample so I'm going to go
ahead and take this water sample here
this water sample is from a pond that
was in Riverside California so I'm going
to take my sterile pipette and I'm going
to take one milliliter of the water so
the line here is a milliliter and now
I'm gonna go ahead and open my petri
dish slightly and I'm going to
put in one milliliter of water I'm going
to swirl it to cover the auger and now
I'm going to go ahead and label this
this is Riverside pond and now I'm gonna
seal it because we never want to open up
the petri dish so I'm gonna seal it with
something called parafilm would you say
wax and it stretches out a little bit
and I'm gonna seal it all the way around
like so and we will never open up the
petri dish because there could be
pathogens in it and so we will look
through the plastic to check for
coliform in a few days
the next test that we're gonna do is on
fish tank water so I went over to my
aquarium and I got a sample here I just
scooped out some water for my fish tank
and so now I'm going to take my pipette
this is a new pipette sterile pipette
and I filled it up to a milliliter here
and I'm going to go ahead and inoculate
in here I swirl it around to cover the
auger make sure my water is covering all
of the auger and I'm going to go ahead
and label this fish tank and I'm going
to seal it up
the next sample here is of tap water so
I just went over to the tap I made sure
that my beaker was clean and I'm gonna
go ahead and use a new sterile pipettes
and I'm going to fill it up to a
milliliter and once again I'm going to
inoculate you'll notice that I am
careful not to leave the lid off too
long on a petri dish and that's really
important to pretend to prevent
contamination from the air from getting
inside of the petri dish and I'm going
to go ahead and seal it and label it
[Music]
let's go ahead and get the results of
our coliform bacteria tests so what
we're gonna do is we're gonna look at
the bottom of each of these to see if
they grew colonies of coliform bacteria
so start here with tap water and so this
is just water from the tap and we turn
it over and we can see here that there
are no colonies which is great there
should not be any colonies in our tap
waters so this came back negatives zero
colonies next we'll look at our fish
tank so our fish tank actually grew
bacteria and you can see some kind of
large colonies in here but not coliform
so it's negative for coliform bacteria
is the coliform bacteria czar kind of a
light pink circle now our fish tank
water does have good bacteria in it
beneficial bacteria and so that's what
we're seeing growing but not coliform so
coliform bacteria comes from mammal
feces and so there are no mammals in my
fish tank so this is normal for it to
come back negative now I'll do some
santa clarita
river water collected in on the Valencia
side of the Santa Clara River and this
one is positive for a couple of there's
one there so one and then there's one
here so two small colonies of coliform
this could be runoff from dog poop or
some sewer lines but probably just
mammals even coyotes or something that
live along the riverbed and so that's
what this is from
so we'll say two colonies in that water
the next one is from the Gilbert Arizona
riparian Preserve and this was treated
wastewater and there this has come back
negative now it has some bacteria in it
but not coliform bacteria and this was
mostly in this water were mostly ducks
and those are not mammals so we are not
getting any fecal coliform which is good
because this is actually treated waste
water and so you wouldn't want any fecal
coliform in your treated wastewater but
it could have some if some mammal
we're living nearby and their waste
washed in but it doesn't look like in
our water sample we have any of that so
this is negative our bottled water
sample so here on the bottled water
sample we are negative for fecal
coliform so that's excellent also there
are a couple of specs these are not
bacterial colonies this was actually
clumps of agar so this is also negative
of fecal coliform this was the ocean
water in Ventura I'm sorry in Oxnard and
it looks like we have a colony here so
it looks like we have one colony of
coliform bacteria and it's a light pink
color this is another sample from the
santa clara river taken when the water
was extremely turbid so very very turbid
water this was the water source almost
black and that was after a rain and this
one is definitely positive you can see
there's a lot of colonies growing and
some of them are coliform so that's
definite coliform bacteria and then that
and then that and then some smaller ones
so it looks to me like we have about
five colonies of fecal coliform so it
means that as that water was washed down
into the river
it picked up some feces along the way so
the next one here is Riverside pond
water so this pond water was also from
reclaimed water so treated wastewater
and it looks to be let me get in the
light
looks to be positive for one so right
there has one colony again probably from
a mammal living nearby and the waste
washing in okay and then this is Whitney
Canyon so a hiking trail in Santa
Clarita and it looks like we do have a
few colonies in here no actually yes we
do some of these are specs from the Agra
the agar cut clumped together and these
specs are just clumped agar but over
here this colony right there is
definitely a very good coliform bacteria
colony it's a nice light pink color so
this is positive for one so this is one
of the reasons why when you're hiking
that you don't drink any Creek water or
stream or lake water without purifying
it running it through a filter or adding
iodine drop or two to your water bottle
or boiling it and that's it
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