Environmental Mutagenesis Lab Manual - MIC-637
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Questions and Answers

What is the primary objective of LAB NO: 1?

  • To study soil health
  • Degradation of octane
  • Isolation of soil-degrading bacteria (correct)
  • Analysis of UV radiation effects

Soil-degrading bacteria are known to worsen soil contamination.

False (B)

What type of hydrocarbons are studied in LAB NO: 3?

Octane

LAB NO: 4 deals with the degradation of ____ by soil bacteria using spray plate technique.

<p>diesel</p> Signup and view all the answers

What were the characteristics of the colonies observed in the negative control?

<p>Well-defined, smooth-edged colonies of uniform size and pigmentation (D)</p> Signup and view all the answers

Match the labs with their main focus:

<p>LAB NO: 1 = Isolation of soil-degrading bacteria LAB NO: 3 = Degradation of octane LAB NO: 4 = Degradation of diesel LAB NO: 5 = UV radiation induces mutagenesis in bacteria</p> Signup and view all the answers

Which process do soil-degrading bacteria contribute to?

<p>Nutrient cycling (A)</p> Signup and view all the answers

The test plate showed significantly larger and well-formed colonies.

<p>False (B)</p> Signup and view all the answers

What type of cells were primarily observed in the positive control after 10 minutes of UV exposure?

<p>Mostly intact pink rods</p> Signup and view all the answers

Which of the following species is oxidase-positive?

<p><em>Pseudomonas</em> (C)</p> Signup and view all the answers

UV radiation has no effect on bacteria.

<p>False (B)</p> Signup and view all the answers

The methodology used in the experiment involved observing bacteria exposed to ___ radiation.

<p>UV</p> Signup and view all the answers

Polycyclic aromatic hydrocarbons (PAHs) are not considered mutagenic or carcinogenic.

<p>False (B)</p> Signup and view all the answers

What environmental problem is associated with greasy soil?

<p>Hydrocarbon contamination</p> Signup and view all the answers

Match the observation condition with its outcomes:

<p>Negative Control = Well-defined colonies with abundant growth Positive Control (10 min) = Some clumping and fragmented cells Test Plate (20 min) = Pronounced abnormalities and minimal growth Overall Implication = Induces lethal mutations in bacteria</p> Signup and view all the answers

What ecological process does the degradation of benzene by microorganisms contribute to?

<p>Environmental health</p> Signup and view all the answers

Soil-degrading bacteria can transform pollutants into more or less ____ forms.

<p>mutagenic</p> Signup and view all the answers

The cotton-soaked method is used to study the biodegradation of __________ by soil bacteria.

<p>benzene</p> Signup and view all the answers

Match the following controls with their descriptions:

<p>Positive control = A minimal media plate + glucose Negative control = A minimal media plate Test plate = A minimal media plate with soaked benzene cotton balls</p> Signup and view all the answers

What is the purpose of making wells in the plates during the experiment?

<p>To place soaked benzene cotton balls (D)</p> Signup and view all the answers

Incubation of the plates occurs at a temperature of 25°C.

<p>False (B)</p> Signup and view all the answers

What method is used to isolate individual bacterial colonies in the experiment?

<p>Serial dilution</p> Signup and view all the answers

What type of media was used in the experiment to observe microbial growth?

<p>Minimal media (B)</p> Signup and view all the answers

Fungal contamination was observed only on one of the plates during the experiment.

<p>False (B)</p> Signup and view all the answers

What are the names of the two bacterial genera mentioned that were viable on nutrient agar?

<p>Bacillus and Pseudomonas</p> Signup and view all the answers

During the experiment, fungal contamination on the filter paper suggested that the experimental conditions favored _____ growth.

<p>fungal</p> Signup and view all the answers

Match the following microbial aspects with their relevance to the experiment:

<p>Hydrocarbons = Environmental pollutants Aseptic conditions = Prevent contamination Fungal contamination = Interfered with assessment Minimal media = Differentiated microbial growth</p> Signup and view all the answers

What could be a potential future direction to reduce contamination in experiments?

<p>Improving aseptic techniques (B)</p> Signup and view all the answers

The presence of diesel in the environment does not pose any ecological risks.

<p>False (B)</p> Signup and view all the answers

What role did the filter paper serve during the experiment?

<p>It was used to observe fungal contamination.</p> Signup and view all the answers

What is the primary objective of the study?

<p>To evaluate the degradation of hydrocarbons by soil microorganisms (A)</p> Signup and view all the answers

The study shows that Bacillus and Pseudomonas are effective in degrading benzene.

<p>False (B)</p> Signup and view all the answers

What are two environmental sources of hydrocarbons mentioned in the content?

<p>Industrial activities, oil spills</p> Signup and view all the answers

The type of media used to grow Bacillus and Pseudomonas was called _____ media.

<p>minimal</p> Signup and view all the answers

Match each microorganism to its expected result in the study:

<p>Bacillus = Negative for benzene degradation Pseudomonas = Negative for benzene degradation</p> Signup and view all the answers

Which of the following represents a potential risk of hydrocarbons in the environment?

<p>Their potential to bioaccumulate (C)</p> Signup and view all the answers

The tests conducted showed positive results for both bacterial species at all experimental stages.

<p>False (B)</p> Signup and view all the answers

What method was used on Day 1 to prepare a master plate?

<p>Stabbing on nutrient agar</p> Signup and view all the answers

What is bioremediation primarily used for?

<p>To break down hydrocarbons (D)</p> Signup and view all the answers

The positive control plate had diesel sprayed on it.

<p>False (B)</p> Signup and view all the answers

Which two genera of bacteria were tested for diesel degradation?

<p><em>Bacillus</em> and <em>Pseudomonas</em></p> Signup and view all the answers

The agar plate marked as the __________ control confirmed bacterial viability on the minimal media.

<p>positive</p> Signup and view all the answers

Match the bacterial growth levels with their corresponding observations.

<p>Positive Control = +++ (growth) Negative Control = ++ (less growth) Test Plate = ++++ (more growth)</p> Signup and view all the answers

What method was used to evaluate the bacteria's ability to metabolize diesel?

<p>Spray plate technique (A)</p> Signup and view all the answers

The study indicated that these bacteria can effectively degrade diesel.

<p>False (B)</p> Signup and view all the answers

How long were the plates incubated during the experiment?

<p>3 days</p> Signup and view all the answers

Flashcards

Soil-degrading bacteria

Microorganisms that break down organic matter in soil, playing a crucial role in nutrient cycling and maintaining soil health.

Soil degradation

The process by which soil-degrading bacteria break down organic matter in soil.

Complex pollutants

Pollutants that can be broken down by certain bacteria into simpler, often less harmful compounds.

Greasy soil

Soil contaminated with hydrocarbons, often from oil spills or industrial activities, posing a major environmental challenge.

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Mutagenesis

The ability of some bacteria to alter the mutagenic properties of certain compounds.

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Spray plate technique

A technique used to isolate and study soil-degrading bacteria by allowing them to grow on a nutrient-rich agar medium.

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Isolation

The process of separating and identifying different bacteria from a sample.

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Nutrient-rich agar

A specific type of nutrient-rich agar medium used to grow bacteria.

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Serial Dilution

A technique used to reduce the number of bacteria in a sample by repeatedly diluting a culture with sterile liquid, allowing for isolation of individual colonies.

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Oxidase Test

A direct method used to distinguish between Pseudomonas and Bacillus species based on their ability to produce an enzyme called cytochrome c oxidase.

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Hydrocarbons

A type of organic compound containing only carbon and hydrogen atoms, often found in petroleum products.

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Polycyclic Aromatic Hydrocarbons (PAHs)

A specific type of hydrocarbon with multiple benzene rings, known for their potential to cause cancer and genetic mutations.

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Biodegradation

The process by which microorganisms break down organic compounds, such as hydrocarbons, into simpler substances.

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Cotton-soaked Method

A method for studying benzene biodegradation in soil by using cotton balls soaked in a benzene solution and placing them in wells on agar plates inoculated with soil bacteria.

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Positive Control

A growth medium containing glucose, used to support bacterial growth in the experiment.

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Negative Control

A growth medium lacking any source of carbon, used as a reference to compare with the test and positive control plates.

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Minimal medium

A specialized growth medium used in microbiology to test for the ability of microorganisms to degrade specific compounds, such as hydrocarbons.

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Bioremediation

A method that uses living organisms, particularly microorganisms, to break down and remove pollutants from the environment.

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Hydrocarbon degradation

The breakdown of complex molecules, in this case hydrocarbons, into simpler molecules by microorganisms.

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Bacillus

A type of bacteria known for its ability to degrade a variety of organic compounds, including hydrocarbons.

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Pseudomonas

A genus of bacteria known for its ability to degrade a variety of organic compounds, including hydrocarbons.

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Stabbing culture

A laboratory technique used to isolate and cultivate microorganisms, often involving growing them on a solid medium in a petri dish.

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Hydrocarbon utilization

The ability of microorganisms to utilize hydrocarbons as a source of carbon for growth and metabolism.

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Nutrient agar

A nutrient-rich agar-based medium commonly used for growing and maintaining bacterial cultures.

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Microbial Culture

The process of growing microorganisms in a controlled environment to study their behavior and characteristics.

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Replication (Microbial)

A technique used to replicate microbial colonies onto new plates for further study.

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Fungal Contamination

A condition where unwanted organisms, like fungi, contaminate a microbial culture, potentially hindering the desired study.

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Hydrocarbon-Degrading Bacteria

A group of bacteria known for their ability to break down hydrocarbons.

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Aseptic Techniques

Maintaining a sterile environment to prevent contamination during experiments.

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UV-induced mutagenesis

UV radiation can cause changes in the DNA of bacteria, leading to mutations.

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Lethal & sub-lethal mutations

Bacteria exposed to UV radiation may show reduced growth or even die.

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Growth density difference

The bacteria on the test plate, exposed to UV radiation, will grow less densely than the control group.

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Microscopic observation of UV damage

The test plate bacteria will show signs of damage like filamentation, lysis, or irregular shapes when observed under a microscope.

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Colony morphology changes

Bacterial colonies exposed to UV light might change their appearance (e.g., smaller, irregular shapes).

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Study Notes

Environmental Mutagenisis Lab Manual - MIC-637

  • Lab course in charge: Ms. IQra
  • Student name: Kainaat
  • Seat no: EH2121042

Index (Lab Experiments)

  • Lab No. 1 (15-10-2024): Isolation of soil-degrading bacteria
  • Lab No. 2 (22-10-2024): Degradation of benzene from soil microorganisms using the cotton soak method.
  • Lab No. 3 (22-10-2024): Degradation of hydrocarbons (octane) by soil microorganisms.
  • Lab No. 4 (4-12-2024): Degradation of hydrocarbon (diesel) by soil bacteria using spray plate technique.
  • Lab No. 5 (11-12-24): UV radiation induces mutagenesis in bacteria.

Lab No. 1: Isolation of Soil-Degrading Bacteria

  • Objective: Isolate soil-degrading bacteria
  • Introduction: Soil bacteria break down organic matter, crucial for soil health and nutrient cycling. Some bacteria can transform pollutants into mutagenic compounds.
  • Soil Bacteria Types: Pseudomonas and Bacillus are effective in hydrocarbon degradation.
  • Sample Collection: 1 gram of greasy soil from a petrol pump collected.
  • Methods:
    • Serial dilution of soil sample (diluted to 10-¹ to 10-⁶)
    • Plating: 0.1mL of dilutions spread on nutrient agar plates.
    • Incubation: Plates incubated at 37°C for 24 hours.

Lab No. 2: Degradation of Benzene by Soil Microorganisms

  • Objective: Observe benzene degradation by soil microorganisms
  • Introduction: Benzene, a common pollutant, is degraded by some soil microorganisms through various processes, often involving breaking down the compound into less harmful substances.

Lab No. 3: Degradation of Hydrocarbons (Octane)

  • Objective: Observe degradation of octane by soil microorganisms.
  • Introduction: Octane is a hydrocarbon commonly found in petroleum, and soil microorganisms play a vital role in its degradation.
  • Methodology: Use a minimal media to observe growth patterns, as well as replicate of cultures using a sterile replicator.

Lab No. 4: Degradation of Hydrocarbons (Diesel)

  • Objective: Observe degradation of diesel by soil bacteria using a spray plate technique.
  • Introduction: Diesel is a complex mixture of hydrocarbons and degrading it is an environmental problem.
  • Methodology: Spray diesel onto minimal media plates and observe bacterial growth.

Lab No. 5: UV Radiation and Mutagenesis in Bacteria

  • Objective: Determine the effects of UV radiation on bacterial mutagenesis.
  • Introduction: UV radiation can cause DNA mutations in bacteria, potentially impacting their survival and growth.
  • Methodology: Expose bacterial cultures (Pseudomonas) to different UV radiation durations (10 minutes, 20 minutes) and observe the results on minimal media plates.

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Description

This lab manual focuses on environmental mutagenesis, detailing experiments aimed at isolating soil-degrading bacteria and understanding their role in pollutant degradation. Students will conduct a series of experiments analyzing the effectiveness of various soil microorganisms in breaking down hydrocarbons and the impact of UV radiation on mutagenesis. Each lab is designed to enhance practical skills in microbiology and environmental science.

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