Fecal Coliform Bacteria Tests

Summary

The 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

00:00

🔬 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.

05:02

🔍 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.

Keywords

💡Inoculate

Inoculation refers to the process of introducing a substance into a culture medium, such as a petri dish, to encourage the growth of microorganisms. In the video, inoculation is used to introduce water samples into petri dishes containing agar, a medium that provides a food source for bacteria, to determine the presence of fecal coliform bacteria.

💡Petri Dish

A Petri dish is a shallow, transparent, and usually circular dish used in laboratories for the culture of bacteria or other microorganisms. It is sealed with a lid and contains agar, a gelatinous substance that serves as a growth medium. In the script, petri dishes are used to grow colonies of bacteria from various water samples.

💡Auger

Auger, in the context of the video, refers to a type of agar used as a growth medium in petri dishes. It is a light yellow substance that provides a food source for bacteria, allowing them to grow and form colonies. The video explains that this particular auger medium causes the growth of pink colonies, which are indicative of fecal coliform bacteria.

💡Fecal Coliform

Fecal coliform bacteria are a group of bacteria that are typically found in the intestines of warm-blooded animals. Their presence in water samples often indicates contamination with fecal matter, which can pose health risks. The video's main theme revolves around testing various water samples for the presence of fecal coliform bacteria using a special auger medium that causes these bacteria to form pink colonies.

💡Sterile Pipette

A sterile pipette is a laboratory instrument used to transfer small volumes of liquid without the risk of contamination. It is crucial in microbiological experiments to ensure that the samples are not contaminated by extraneous microorganisms. In the video, a sterile pipette is used to accurately measure and transfer one milliliter of water samples into the petri dishes.

💡Water Sample

A water sample is a portion of water collected for the purpose of testing or analysis. In the context of the video, water samples are taken from various sources such as a pond, fish tank, tap, treated wastewater, bottled water, ocean water, and a hiking trail to test for the presence of fecal coliform bacteria. The script describes the process of collecting and inoculating these samples into petri dishes.

💡Parafilm

Parafilm is a brand of sealant film used in laboratories to create an airtight seal on containers such as petri dishes. It is stretchable and adheres to itself, preventing the ingress of contaminants. In the video, parafilm is used to seal the petri dishes after inoculation to prevent contamination and to maintain the sterility of the samples.

💡Pathogens

Pathogens are disease-causing microorganisms, such as bacteria, viruses, or fungi, that can cause illness in their hosts. The video emphasizes the importance of sealing petri dishes to prevent the potential pathogens from the water samples from contaminating the environment. Pathogens like fecal coliform bacteria are the focus of the tests being conducted.

💡Colonies

In microbiology, colonies refer to visible clusters of identical microorganisms that have grown from a single cell or group of cells on a solid medium. The video script describes the observation of colonies in petri dishes to determine the presence of fecal coliform bacteria. Pink colonies growing on the auger indicate the presence of these bacteria.

💡Treated Wastewater

Treated wastewater refers to water that has undergone a treatment process to remove contaminants and make it suitable for reuse or discharge into the environment. In the video, one of the water samples is treated wastewater from the Gilbert Arizona riparian Preserve. The script notes that it tested negative for fecal coliform bacteria, which is expected as the water has been treated to remove such contaminants.

💡Contamination

Contamination is the presence of unwanted substances or impurities in a sample or environment. In the context of the video, contamination is a concern when handling petri dishes, as opening the lid for too long can allow airborne contaminants to enter and affect the results of the bacterial growth. The script emphasizes the importance of minimizing lid opening time to prevent 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