Description

Overview of the Assignment

The core of this assignment revolves around a collaborative effort where groups of up to five students are provided with a worksheet to conduct guided research on a specific microorganism. This task is structured to fit within a 55-minute class period, making it an ideal activity for class sizes ranging from 10-30 students. The primary objective is to enhance students’ understanding of microbes through guided research, followed by group presentations that allow them to showcase their findings.

4DEE Alignment
The activity aligns with the 4-Dimensional Ecology Education (4DEE) framework, particularly in the dimension of Core Ecological Concepts and Ecology Practices.

I. Core Ecological Concepts

The activity touches upon several core ecological concepts categorized under individuals, populations, communities, and ecosystems through the exploration of microbial diversity. It delves into:

• Individuals and Populations: By investigating specific microorganisms, students learn about the diversity of individual organisms (bacteria and archaea) and their roles within their populations. This includes understanding their metabolic functions and adaptations to various environments, which are fundamental concepts in ecology regarding how organisms interact with their biotic and abiotic environments.
• Communities and Ecosystems: The assignment extends to the community and ecosystem levels by exploring the ecological roles of microorganisms. This encompasses their contributions to nutrient cycling, energy flow, and ecosystem health, highlighting interactions like mutualism, predation, and competition within microbial communities. The focus on extremophiles and their adaptations to extreme environments also sheds light on the resilience and stability of microbial communities in varying ecosystems.
• Trophic Levels and Energy Flow: The segment on metabolic functions indirectly addresses trophic levels and energy flow within ecosystems, as students explore how microorganisms act as producers, consumers, and decomposers, thereby facilitating energy transfer and nutrient cycling.

II. Ecology Practices

This activity directly engages students in several ecology practices as outlined in the 4DEE framework:

• Making Observations and Collecting Data: Students start by researching specific microorganisms, making observations about their characteristics, metabolic processes, and ecological roles.
• Generating and Testing Hypotheses: While not explicitly stated, the activity’s research component could lead to hypothesis generation about the ecological impact of certain microorganisms or their evolutionary adaptations.
• Data Analysis and Interpretation: By analyzing the information gathered during their research, students are involved in synthesizing and interpreting data to understand the ecological significance of their assigned microorganisms.
• Communication and Collaboration: The group presentation aspect of the assignment fosters communication and collaboration among students, essential practices in ecological research and education.
• Interdisciplinary Integration: Highlighting the intersection of microbiology with environmental science, biochemistry, and biotechnology, the activity demonstrates the interdisciplinary nature of ecology, connecting biological concepts with practical applications and real-world problems.

In summary, the “Exploring Microbial Diversity” activity integrates core ecological concepts with hands-on ecology practices. It provides a comprehensive approach to learning that not only enhances students’ understanding of microbial ecology but also develops essential scientific skills and competencies in line with the 4DEE framework. This holistic educational experience prepares students to think critically and creatively about ecological problems and their solutions, embodying the 4DEE’s goal of producing ecologically literate individuals.

Components of the Resource

1. Detailed Instructor Instructions: To ensure smooth execution of the activity, the resource includes thorough instructions for instructors, outlining steps for preparation, group formation, and assessment criteria. This preparation requires minimal time, estimated at around 10 minutes, allowing instructors to efficiently integrate the activity into their lesson plans.
2. Student Worksheet: A carefully designed worksheet guides student research, focusing on the classification, metabolism, and ecological significance of assigned microorganisms. This component encourages students to engage with scientific literature and databases, honing their research skills.
3. PowerPoint Presentation with Microorganism Images: Accompanying the assignment is a PowerPoint presentation, equipped with images of the microorganisms for visual support. These visuals serve as a critical aid during group presentations, enhancing comprehension and retention of information.
4. Pre-Activity Quiz: Included in the resource is a pre-activity quiz designed to assess students’ baseline knowledge of microbiology. This quiz helps instructors gauge the prior understanding of their students, allowing for tailored discussions that address any gaps in knowledge before beginning the assignment.
5. Post-Activity Quiz: Following the completion of the assignment, a post-activity quiz is provided to evaluate the knowledge gained through the research and presentation phases. This quiz serves as a tool for both students and instructors to measure the effectiveness of the activity in enhancing understanding of microbiological concepts and identify areas for further study.
6. Interdisciplinary Integration: The assignment is crafted to highlight the interdisciplinary nature of microbiology, connecting it with fields such as environmental science, biochemistry, and biotechnology. This approach not only broadens students’ understanding but also illustrates the real-world applications of microbiological concepts.

Lesson Learning Goals:

1. Understand Microbial Diversity: Students will identify and differentiate between various microorganisms, including bacteria and archaea, recognizing the vast diversity present in the microbial world.
2. Explore Metabolic Processes: Learners will describe the metabolic functions of assigned microorganisms, such as chemoautotrophy, photoautotrophy, and heterotrophy, and understand how these processes enable survival in diverse environments.
3. Investigate Environmental Adaptations: Students will examine how specific microorganisms have adapted to their environments, including extremophiles that thrive in conditions like high temperatures, acidity, or salinity.
4. Develop Research Skills: Through guided research, students will enhance their ability to find, analyze, and synthesize scientific information from reputable sources.
5. Foster Collaboration: Working in groups, students will improve their teamwork and communication skills, learning to effectively collaborate on a scientific investigation.
6. Enhance Presentation Skills: By preparing and delivering a group presentation, learners will develop their ability to communicate scientific concepts clearly and confidently to an audience.
7. Promote Interdisciplinary Thinking: Students will connect microbiology to other disciplines, such as environmental science, biochemistry, and biotechnology, appreciating the role of microorganisms across various fields.
8. Encourage Scientific Inquiry: The activity aims to spark curiosity about the microscopic world, motivating students to ask questions, seek answers, and consider the implications of microbial life on broader ecological and human scales.

Lesson Learning Objectives:

By the end of this lesson, students will be able to:

1. Identify key characteristics that differentiate bacteria from archaea and explain the significance of microbial diversity.
2. Describe the metabolic processes of assigned microorganisms, including their energy acquisition methods and their role in the ecosystem.
3. Explain how specific microorganisms adapt to extreme environments, detailing the mechanisms that enable their survival in conditions such as high temperature, acidity, or salinity.
4. Conduct research using credible scientific sources to gather information about their assigned microorganism.
5. Collaborate effectively with peers to complete a worksheet on the characteristics, metabolic processes, and environmental adaptations of specific microorganisms.
6. Present their findings in a clear and engaging manner, using visual aids and concise explanations to communicate their research to the class.
7. Apply interdisciplinary approaches to understand the role of microorganisms in environmental science, biochemistry, and biotechnology, illustrating the impact of microbiology beyond the laboratory.
8. Demonstrate curiosity and scientific inquiry by asking thoughtful questions and seeking out additional information about the microbial world, showing an appreciation for its complexity and relevance to human life.

Intended Audience

This activity was designed for lower-level biology courses for majors and STEM or pre-health majors at a two-year college. Students should be comfortable with technology in the classroom and be able to connect to the internet on their laptops or other electronic devices that support the use of a web browser and search engine.

Required Learning Time

The required time to complete this activity is approximately 55 minutes. However, this may vary depending on the classroom because of the inclusion of primary literature, several open-ended questions, and opportunities for discussion.

Prerequisite Student Knowledge

For successful participation in this in-class assignment, students must have a foundational understanding of prokaryotic organisms from prior coursework or reading, such as “Biology: Concepts and Investigation” textbook, Chapter 17: Bacteria and Archaea(1). This background includes basic knowledge of microorganisms’ classification, structure, and general metabolic functions, with a particular focus on bacteria and archaea. Prior learning should cover the essential roles these organisms play in the biosphere, from their contributions to ecosystem functioning to their applications in biotechnology. This preliminary knowledge will enable students to delve into the detailed study of the diversity, specialized metabolic pathways, and environmental adaptations of specific microorganisms. Through targeted research and presentations on selected bacteria and archaea, students will expand their grasp of these microscopic life forms’ complex interactions and significance in both scientific and societal contexts.

Introduction

Though often invisible to the naked eye, microorganisms are pivotal to sustaining life on Earth. They inhabit every possible niche, from the deepest oceans to the highest mountains, playing essential roles in nutrient cycling, ecosystem stability, and even in developing new technologies within the biotechnology field. The vast diversity of the microbial world, particularly bacteria and archaea, offers a rich tapestry of life forms for scientific exploration. This in-class assignment, “Exploring Microbial Diversity,” is meticulously designed to navigate students through the complexity and significance of these microorganisms, emphasizing their classification, metabolic functions, and ecological roles.

Classification and Diversity

The classification of microorganisms as bacteria or archaea lays the foundation for understanding microbial diversity. Bacteria, with their vast array of shapes, sizes, and metabolic capabilities, coexist with archaea, which are renowned for their resilience in extreme environments (1). This worksheet segment encourages students to delve into the taxonomy of microorganisms, facilitating an appreciation of the evolutionary pathways that have led to the current classification system. Understanding this classification is crucial for grasping the broader ecological impacts of microorganisms and their evolutionary significance.

Metabolic Functions

Microbial metabolism encompasses a broad spectrum of processes fundamental to life on Earth. From photoautotrophs that harness sunlight to chemolithotrophs thriving on inorganic compounds (2), the metabolic diversity of microorganisms is a testament to their adaptability and role in biogeochemical cycles. This worksheet component invites students to explore these metabolic processes, linking them to environmental sustainability and the potential for biotechnological applications.

Ecological Roles

The ecological roles of microorganisms are as diverse as the organisms themselves (3). This section of the worksheet focuses on the symbiotic relationships microorganisms form with plants, animals, and each other, as well as their contributions to nutrient cycling and ecosystem health. Students will investigate how microorganisms are integral to processes such as nitrogen fixation, decomposition, and even climate regulation, highlighting their indispensable role in maintaining life on Earth.

Adaptations to Various Environments

The remarkable ability of microorganisms to adapt to various environments underscores their evolutionary success. From extremophiles that thrive in hot springs and acidic environments to mesophiles living in moderate conditions, this part of the worksheet showcases the physiological and genetic adaptations that enable microorganisms to inhabit diverse habitats. Through this exploration, students will gain insights into the resilience and versatility of microbial life, offering perspectives on how life can exist under seemingly inhospitable conditions (4).

Through “Exploring Microbial Diversity in the Classroom,” students are invited on a journey through the microscopic world, uncovering microorganisms’ hidden yet profound influence on our planet and beyond. This assignment not only cultivates a deeper understanding of microbial life but also inspires curiosity and respect for our world’s tiny, yet mighty, inhabitants.

List of Potential Microorganisms for Inclusion in this Activity

The organisms chosen for the “Exploring Microbial Diversity” activity represent a diverse set, deliberately selected to address common misconceptions and highlight the broad spectrum of microbial life. Contrary to the widespread belief that only archaea are found in extreme environments, bacteria and archaea exhibit remarkable adaptability, thriving across various habitats from the extreme to the mundane (5). This selection aims to underscore the evolutionary success and adaptability of microorganisms. Here, we discuss the principal differences and similarities between bacteria and archaea, grounding our exploration in the context of classroom learning.

Main Differences Between Bacteria and Archaea:

1. Cell Wall Composition:
   • Bacteria possess a cell wall made of peptidoglycan, a unique polymer of sugars and amino acids (5).
   • Archaea have cell walls that lack peptidoglycan; their cell walls may contain pseudopeptidoglycan or other polymers not found in bacteria, distinguishing their cellular architecture (6).

2. Membrane Lipids:
   • Bacteria’s membrane lipids are composed of fatty acids attached to glycerol by ester linkages, a characteristic feature of their membranes (5)
   • Archaea feature ether linkages between glycerol and isoprenoid chains in their membrane lipids, which can form monolayers or bilayers, contributing to their stability in extreme conditions (6).
3. Gene Expression Machinery:
   • Bacteria utilize a simpler form of RNA polymerase and a translation process that is more distinct from eukaryotes, reflecting their evolutionary lineage (5)
   • Archaea’s RNA polymerases resemble those of eukaryotes, and they share more similarities in the translation process and factors involved, suggesting a closer evolutionary relationship in some aspects of gene expression (6)

Similarities Between Bacteria and Archaea:

1. Prokaryotic Cell Structure: Both domains consist of prokaryotic organisms, lacking a nucleus and other membrane-bound organelles, which simplifies their cellular organization (5)
2. Reproduction: Both bacteria and archaea reproduce asexually, primarily through binary fission, and are capable of exchanging genetic material via mechanisms akin to horizontal gene transfer, facilitating genetic diversity (5)
3. Ecological Roles: They play pivotal roles in their ecosystems, including nutrient cycling, forming symbiotic relationships, and acting as primary producers in certain environments, underscoring their ecological importance (5)

By incorporating these discussions into the classroom through the “Exploring Microbial Diversity” activity, educators aim to deepen students’ understanding of microbial life, challenging existing misconceptions and fostering an appreciation for the complexity and pervasiveness of microorganisms across different environments.

Example Microorganisms

The provided examples illustrate the wide range of diversity found within the Bacteria and Archaea domains, underscoring their various habitats and ecological functions. Additional examples can be incorporated as deemed appropriate by the instructor. For a class of 28 students, dividing them into 6 groups, each consisting of 4 to 5 students, has been effective previously.

Bacteria:

• Escherichia coli (E. coli) - A common bacterium found in the intestines of humans and animals. While most strains are harmless, some can cause serious food poisoning.
• Staphylococcus aureus - A bacterium found on the skin and in the respiratory tract of humans. It’s known for causing skin infections, pneumonia, and sometimes food poisoning.
• Streptococcus pneumoniae - This bacterium is found in the human respiratory tract and can lead to pneumonia, meningitis, and other infections.
• Bacillus subtilis - Known as a soil bacterium, it is widely used in biotechnological and genetic studies. It’s considered non-pathogenic and has a role in the fermentation of foods.
• Thermus aquaticus (Taq) - This bacterium is found in hot springs and hydrothermal vents. It is famous for its enzyme, Taq polymerase, which is a thermostable DNA polymerase used in the polymerase chain reaction (PCR) technique. PCR is a method widely used in genetic testing, research, and forensic science to amplify segments of DNA. Taq polymerase’s ability to withstand high temperatures, necessary for PCR, has made it an invaluable tool in biotechnology and molecular biology.

Archaea:

• Methanobrevibacter smithii - Predominantly found in the human gut, involved in the digestion process and methane production.
• Halobacterium salinarum - Thrives in high-salt environments, such as salt lakes and salt pans, and is known for its pink or red pigmentation due to carotenoid proteins.
• Thermococcus litoralis - A thermophilic archaeon found near hydrothermal vents, it thrives at high temperatures and is used in industrial processes for its stable enzymes.
• Sulfolobus acidocaldarius - Lives in acidic and high-temperature environments such as hot springs. It’s interesting for research due to its unique metabolic processes and ability to withstand extreme conditions.

In-Class Lecture Script

These step-by-step instructions are designed to provide instructors with a structured approach to conducting an interactive and informative lecture on microorganisms, setting the stage for a deeper exploration through the “Exploring Microbial Diversity” assignment.

Objective: To guide students through the fascinating world of microorganisms, highlighting their classification, metabolic functions, ecological roles, and adaptations. This lecture aims to complement the “Exploring Microbial Diversity” assignment by providing foundational knowledge and stimulating curiosity and engagement among students.

Preparation:

1. Review Lecture Content: Familiarize yourself with the lecture slides and script, focusing on the four key aspects of microorganisms: classification, metabolic functions, ecological roles, and adaptations.
2. Prepare Visual Aids: Ensure that the PowerPoint slides are ready for presentation, with clear images and bullet points that cover the diversity of microorganisms, their metabolic functions, ecological roles, and examples of extremophiles.
3. Set Up Classroom: Arrange seating to facilitate discussion, ensuring that all students can see the presentation and participate in the interactive segments.

Lecture Execution:

Introduction:

1. Start with a brief overview of the importance of microorganisms in the biosphere and their impact on ecosystem health and biotechnology.
2. Introduce the main topics of the lecture: classification and diversity, metabolic functions, ecological roles, and environmental adaptations of microorganisms.

Classification and Diversity:

1. Present the first slide on microbial diversity, emphasizing the differences between bacteria and archaea.
2. Interactive Segment: Ask students why the distinction between bacteria and archaea is important. After responses, highlight their evolutionary significance and environmental interactions.

Metabolic Functions:

1. Move to the slide on metabolic functions. Describe the variety of ways microorganisms obtain energy and carbon, including photosynthesis, chemolithotrophy, and fermentation.
2. Interactive Segment: Pose a question about the consequences for our planet if microorganisms did not perform these functions. Discuss the students’ responses, emphasizing the critical role of microbes in nutrient cycling.

Ecological Roles:

1. Present information on the ecological roles of microorganisms. Discuss their contributions to decomposition, nitrogen fixation, and climate regulation.
2. Interactive Segment: Ask about the relevance of microbial roles in climate regulation today. Use student responses to talk about the potential of microbes in addressing climate change.

Adaptations to Various Environments:

1. Show examples of extremophiles and their unique adaptations to extreme environments.
2. Interactive Segment: Encourage students to share examples of extremophiles and describe their environments. Highlight how these organisms expand our understanding of life’s potential resilience and diversity.

Conclusion:

1. Summarize the key points covered in the lecture, reinforcing the significance of microorganisms to science and society.
2. Final Interactive Segment: Open the floor for any questions or thoughts students might have about microorganisms. Engage in a brief discussion based on their queries.

Wrap-Up:

• Conclude the lecture by expressing your anticipation for the students’ presentations and their exploration of microorganisms in the upcoming assignment.
• Remind students of the date for their presentations and encourage them to start preparing with their groups.

Follow-Up:

• Consider setting up a dedicated time for students to ask questions or seek guidance on their assignments either during office hours or via an online platform.

Active Learning

The “Exploring Microbial Diversity in the Classroom” lesson incorporates active learning principles to enhance student engagement and deepen understanding in biology and microbiology. By engaging students in collaborative research, critical thinking, and the application of knowledge, this approach shifts the focus from passive reception to active participation. Students work in groups to research and present on various microorganisms, promoting peer teaching and collaborative problem-solving. The lesson further enriches learning by incorporating visual aids, such as PowerPoint presentations with microbial images, catering to diverse learning styles. Interactive presentations and discussions practice communication skills and foster a dynamic exchange of ideas, enhancing the learning experience. This active engagement is complemented by interdisciplinary integration, highlighting the relevance of microbiology in broader scientific and applied contexts. Ultimately, this active learning context not only bolsters students’ comprehension of microbiological concepts but also cultivates essential skills like research, teamwork, and public speaking, making the educational journey both comprehensive and engaging.

Assessment

The “Exploring Microbial Diversity” assessment is multi-dimensional, aimed at evaluating students’ understanding of microbiological concepts, research and synthesis skills, and proficiency in collaboration and presentation. The worksheet component allows individual assessment of assigned microorganisms’ research, assessing understanding of microbial diversity and environmental adaptations. Group presentations then evaluate the collective ability to convey findings clearly and accurately, incorporating visual aids for enhanced communication and testing public speaking and teamwork. Peer and self-assessment encourage reflection on each member’s role and the group’s dynamics, promoting personal accountability and growth. Additionally, instructor feedback on the worksheet and presentation provides critical insights into students’ performances, highlighting achievements and areas for improvement. Participation and engagement are also assessed, considering students’ involvement in discussions and responsiveness during peer presentations, ensuring a comprehensive evaluation of cognitive understanding and soft skills development.

Conclusion

“Exploring Microbial Diversity” represents a shift towards more interactive and student-centered learning in science education. By merging research, collaboration, and presentation into a single assignment, this resource offers a dynamic way to explore the microscopic world. It enriches the biology curriculum and prepares students with the critical thinking and teamwork skills necessary for future scientific endeavors. This resource demonstrates the power of active learning in fostering a deeper understanding and appreciation of the natural world.

References

1.         Hoefnagels M. 2021. Biology: Concepts and Investigations, 5th ed. McGraw Hill.

2.         Schink B. 1997. Energetics of syntrophic cooperation in methanogenic degradation. Microbiol Mol Biol Rev 61:262–280.

3.         Falkowski PG, Fenchel T, Delong EF. 2008. The microbial engines that drive Earth’s biogeochemical cycles. Science 320:1034–1039.

4.         Rothschild LJ, Mancinelli RL. 2001. Life in extreme environments. 6823. Nature 409:1092–1101.

5.         Madigan MT, Bender KS, Buckley DH, Sattley WM, Stahl DA. 2020. Brock Biology of Microorganisms16th edition. Pearson.

6.         Woese CR, Kandler O, Wheelis ML. 1990. Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya. Proc Natl Acad Sci U S A 87:4576–4579.

For a class with 30 students, please print five copies of the cards located on the following two pages, ensuring they are printed double-sided. After printing, cut out each microorganism card. Then, distribute one card to every student and instruct them to form groups based on the cards they receive.

For a class with 30 students, please print five copies of the cards located on the following two pages, ensuring they are printed double-sided. After printing, cut out each microorganism card. Then, distribute one card to every student and instruct them to form groups based on the cards they receive.

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