- Bacteria
- Viruses
- Fungi
- Prions
- Protozoans
- Protist
- Helminths

Types of Microbes

Microbes are too small to be seen with the naked eye, so humans have developed techniques and technology to observe and study them.

Visualizing Microbes

Microbial genetics is the study of the microbial cell genetic storage in the form DNA and its mechanisms of replication and expression.

Microbial Genetics

Microbial growth is indicated by the increase in number of cells by division of parent cells into daughter cells. 

Microbial Growth

Epidemiology

Microbial ecology is the study of microbial populations and how they interact with their environment.

Microbial Ecology

What is a microbe?

Which of the following best describes a microbe?

Which of the following is NOT considered a microbe?

Which of the following environments can microbes be found in?

Most microorganisms are harmless and many provide significant benefits. They form the backbone of many food webs, playing fundamental roles in ecosystems globally. Additionally, humans utilize microbes in various ways, including the production of biofuels, medicines, and foods such as bread, cheese, and beer.

Ecological and Human Uses of Microbes

Long before microscopes were invented, humans possessed a basic awareness of microbial life. Historical evidence indicates that since prehistoric times, humans have utilized microorganisms to create foods, as well as to prevent and treat diseases.

Prehistoric Knowledge of Microorganisms

Even prior to the invention of the microscope, various ancient civilizations recognized that diseases could be transmitted by invisible entities, which are now understood to be microbes. This early awareness of communicable diseases led to the implementation of public health measures, such as quarantining the sick and building comprehensive sanitation systems, to mitigate the spread of infections.

Ancient Understanding of Disease Transmission

The vast majority of microbes are unicellular and require artificial magnification to be observed. However, there are important exceptions: some unicellular microbes are visible to the naked eye, and some multicellular organisms are microscopic. While an object must measure approximately $${}100$$ micrometers (µm) to be visible without a microscope, most microorganisms are significantly smaller. For perspective, a typical microscopic animal cell is roughly $${}10$$ µm across, bacterial cells average about $${}1$$ µm, and viruses can be up to $${}10$$ times smaller than bacteria.

Size of Microorganisms

Microorganisms are highly diverse and differ from one another in various characteristics, including size, structure, habitat, and metabolism. While many microbes are unicellular, there are also multicellular organisms that are microscopic. Additionally, certain microbes, such as viruses, are acellular, meaning they are not composed of cells at all.

Diversity of Microorganisms

Microorganisms, or microbes, are small organisms that are generally too small to be seen without a microscope. They are highly abundant and can be found almost everywhere on Earth, from boiling thermal hot springs to deep beneath the Antarctic ice. While the vast majority of this invisible world remains unexplored, microbiologists continue to discover new ways in which microbes interact with the environment and humans.

University of Wisconsin - Madison

Austin Community College

University of Michigan - Ann Arbor

Google

University of Notre Dame

The study of small organisms ranging from one cell to few cells to no cells at all. It encompasses fields such as virology, bacteriology, protistology, & mycology.

Microbiology

https://openstax.org/details/books/microbiology/

Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

OpenStax Microbiology Textbook

References for microbiology

The field of Microbiology impacts society in many positive ways including the discovery and development of antimicrobials,  the use of bioremediation to clean the environment, phage therapy, food production, vaccine development, and genetic engineering.

Microbiology Contributions and it's Impact on Society

Key scientists and their research led to our understandings about the field of Microbiology.

Notable Scientists in Microbiology

What does the field of microbiology study?

Which of the following fields are encompassed by microbiology?

What types of organisms does microbiology study?

Which of the following best describes the scope of microbiology?

Microbes

Microbial culturing is a laboratory procedure where a biological sample is placed in special dishes to encourage the growth of microorganisms, such as bacteria or fungi. Because microorganisms require time to reproduce into sufficient quantities, it can take a while before they can be effectively detected and analyzed.

Microbial Culturing

As microbiology has developed, it has allowed the broader discipline of biology to grow and flourish in previously unimagined ways. Much of human knowledge concerning cells and their genetics is derived from an understanding of microbes, and many tools currently used to study cells originate from work with microorganisms.

Microbiology's Impact on Biology

While microbiology broadly encompasses the study of all microorganisms, microbiologists in practice typically specialize in one of several subfields. These major disciplines include bacteriology (bacteria), mycology (fungi), protozoology (protozoa), parasitology (helminths and other parasites), and virology (viruses). Immunology is also frequently included in microbiology because host-pathogen interactions are central to understanding infectious disease processes. Other areas of specialization include clinical, environmental, applied, and food microbiology.

Disciplines in microbiology

Microbiology studies and clinical practice must be guided by a core set of ethical principles to protect individuals and ensure scientific integrity. Key requirements include conducting studies with integrity, obtaining informed consent from participants, respecting patients' rights, maintaining accurate records, ensuring confidentiality, and communicating honestly. Additionally, all research procedures involving humans must be approved by an institutional review board, and protocols using animals must be cleared by an institutional animal care and use committee.

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