Microbial Diversity: Eukaryotic and Pathogenicity

🧪 Staining Theory

Staining theory will be on the first exam, but the method of staining will be covered in the lab.

🦠 Eukaryotes in Microbiology

This class mainly focuses on prokaryotes, particularly bacteria. However, it is important to be aware of eukaryotic organisms, which have a nucleus and can be microscopic cells or single-celled organisms.

There are more diseases caused by viruses and bacteria than by eukaryotic organisms. However, eukaryotic organisms are still very important and can cause public health disturbances.

Giardia Lamblia Example

Giardia lamblia is an example of a eukaryotic organism that causes giardiasis. Giardiasis is when you drink water from a stream without filtering it. Giardia lamblia is the most common cause of stomach upset and diarrhea in the United States from drinking unfiltered water.

Transmission

Giardia is easily transmitted through contaminated water supplies. To prevent infection, always filter water or add iodine.

Five Areas of Eukaryotic Organisms

There are five areas of eukaryotic organisms that cause pathogenicity or disease in humans. These are protozoa, helmets, fungi, algae, and lichens. The main focus will be on the key properties that distinguish each from one another.

Protozoa

Protozoa are a category of single-celled, eukaryotic organisms that don't have a lot in common. They are non-algae and non-fungi, as well as non-photosynthetic and motile.

Examples of protozoa include paramecium, amoeba, and euglena.

• Paramecia move using cilia in a swimming motion.

• Amoeba are polymorphic and use pseudopods to grab their environment and pull themselves along.

• Euglena use a flagella to move.

Protozoa are typically found in aquatic environments, but can also be found in terrestrial or soil samples.

Life Forms of Protozoa

Many protozoa are free-living, but some are parasitic and need a host to live inside of. Protozoa have two different life forms:

• Trophozoites:

  The feeding and growth stage of the protozoa, where they actively take in nutrition, reproduce, and grow.

• Cyst:

  A protective wall around the protozoa, similar to an endospore in bacteria, which allows them to survive in unfavorable conditions such as limited nutrition or incorrect temperature.

Protozoa can reproduce asexually.

Protozoa Reproduction 🦠

Asexual Reproduction: Schizogony

Schizogony is a unique form of asexual reproduction seen in protozoa. It involves:

1. One cell with one nucleus.

2. The nucleus reproduces multiple times within the same cell, forming a schizont (a cell with multiple nuclei).

3. The cell undergoes cytokinesis, splitting into multiple cells.

4. Each nucleus gets its own cell, called a merozoite.

   Merozoites: Individual cells formed after schizogony, each containing a nucleus.

This process allows one cell to produce multiple offspring by protecting several nuclei within a single cell until they are ready to be released. It may be triggered by environmental factors such as pH changes within a host's gastrointestinal tract.

Sexual Reproduction

Protozoa can also reproduce sexually through mitosis and meiosis, similar to animal and human cells. Some protozoa can do both asexual and sexual reproduction, depending on the availability of partners and environmental conditions.

Helminths (Worms) 🪱

Helminths are multicellular, larger worm-like organisms whose eggs and larvae are microscopic. They are considered animals with organ systems, although their digestive tracts may be limited.

Importance of Microscopic Identification

The microscopic identification of helminth eggs and larvae is important for diagnosing parasitic infections. Fecal samples may be examined to detect the presence of these microscopic stages.

Major Phyla of Helminths

The two major phyla of parasitic helminths are:

• Nematoda (Roundworms): Characterized by being unsegmented and having a full digestive system.

• Platyhelminthes (Flatworms): Flat-bodied worms, often with suckers and hooks for attachment to the host.

Parasitic Helminths: Nematodes

Nematodes are abundant, with more than 15,000 species.

• They are unsegmented worms with a complete digestive system.

• Several nematode species are human parasites, including:

  • Pinworms: Cause itching and scratching, particularly in children.

  • Trichinella spiralis: Acquired from eating undercooked meat, especially pork.

Parasitic Helminths: Platyhelminthes

Platyhelminthes include flukes, sometimes called blood flukes or trematodes.

• They often associate with animals like beef and pork.

• Many have oral suckers and hooks to attach to the host's intestines for nutrition.

Attachment Mechanisms

Helminths use structures like oral suckers and hooks to attach to the inside of their hosts, allowing them to acquire nutrition.

🪱 Helminths

Platyhelminthes (Flatworms)

• Includes tapeworms, such as the beef tapeworm.

• Tapeworms are segmented flatworms with hooks and suckers.

• Characterized by segmentation, which distinguishes them from nematodes.

Nematodes

• Smooth overall shape compared to platyhelminthes.

Parasitic Nature

• Many helminths are parasitic, but not all.

• Some can cause diseases in animals and humans.

Confusion with Fungi

• Confusion can arise between helminths and fungal infections, like ringworm.

• Human ringworm is actually a type of fungi, not a helminth.

🍄 Fungi

General Characteristics

• A very diverse group of organisms.

• Heterotrophic: Acquire nutrition through various mechanisms.

• Some fungi are saprozoic, meaning they grow on dead matter.

• Illnesses caused by fungi are called mycoses.

Opportunistic Infections

• Some fungi don't typically cause problems in healthy individuals but can cause opportunistic infections.

• Candida albicans is a type of yeast that lives on our bodies and is usually kept in check by the immune system. However, in individuals with compromised immune systems (e.g., advanced HIV), it can overgrow and cause thrush.

Benefits of Fungi

• Helpful in food production.

• Source of many antibiotics, such as penicillin.

Diversity of Fungi

• Can be single-celled or multicellular.

• Fungi have diverse and complex replication cycles.

Vocabulary

Reproduction

• Reproduce both asexually and sexually.

• Single-celled fungi (yeast) typically reproduce asexually by budding.

• During budding, a mother cell develops a protrusion that eventually pinches off to form a daughter cell. Unlike binary fission, the daughter cell may not be the same size as the mother cell.

Hyphae Types

Dimorphism

• Environmental changes, such as nutrient availability and temperature fluctuations, can cause fungi to switch between stages.

Cell Walls

• Fungi have cell walls made of chitin.

• In contrast, plant cells have cell walls made of cellulose, and bacterial cell walls are made of peptidoglycan.

🍄 Fungi

Cell Membrane

Fungi have plasma membranes similar to other cells, but they contain ergosterol instead of cholesterol, which is found in animal cells.

Environmental Benefits

Fungi are essential for:

• Decomposition: Breaking down larger bodies into smaller units and recycling nutrients.

• Edible Forms: Mushrooms like morels and truffles can be eaten.

• Fermentation: Single-celled yeast, Saccharomyces cerevisiae, is used in beer, wine, and bread production. They use carbon dioxide and produce byproducts such as alcohol.

• Antibiotic Production: Fungi produce antibiotics like penicillin, which can be used to fight bacterial infections.

Disadvantages

Fungi can:

• Cause Food Spoilage: Bread molds can lead to food rotting faster, which is why refrigeration is used to prevent mold spread.

• Be Pathogenic:

  • Aspergillus produces aflatoxins, which can harm the human immune system.

  • Cause nuisance health issues like athlete's foot and ringworm.

  • Candida albicans can cause yeast infections.

Summary

Fungi exist in single-celled (yeast) and multicellular forms and have both benefits and disadvantages, with some species being pathogenic.

🌊 Algae

General Characteristics

Algae are:

• Autotrophic: Self-feeding organisms that derive energy from the sun through photosynthesis.

• Unicellular or Multicellular: They can exist as single cells or as multicellular organisms.

• Oxygen Producers: Responsible for about 70% of oxygen and organic compounds in aquatic environments.

Benefits

Algae provide:

• Nutrients: They provide nutrients to aquatic environments.

• Food Source: They serve as a food source for various organisms in water systems.

• Agar: Red algae are used to produce agar, a solidifying agent for agar plates in labs. A similar version called agarose is used in DNA gels.

• Food Thickeners: Derivatives of algae are used in foods like gummy bears as solidifying agents.

Types of Algae

There are many different types of algae, including:

• Red algae

• Green algae

• Brown algae

• Gold algae

• Diatoms

• Dinoflagellates

• Seaweed

Harmful Effects

Algae can be harmful due to:

• Nutrient Depletion: They can grow in large quantities and choke out nutrients from other organisms.

• Toxin Production: Some algae produce toxins that can be harmful if they contaminate water supplies used for recreation or drinking.

Algae vs. Cyanobacteria

• Algae are eukaryotic photosynthetic organisms.

• Cyanobacteria are prokaryotic photosynthetic bacteria.

Variety in Shapes and Morphology

Algae exhibit diverse shapes and morphologies:

• Sea Kelp: A type of brown algae that resembles plants with leaves and stems.

• Red Algae: Some species look like flowers.

• Bioluminescence: Dinoflagellates can cause ocean waves to glow blue at night.

• Diatoms: Produce geometric silicone patterns.

• Green Algae: Form interesting spheres with smaller spheres inside.

Toxicity

Typically, algae are not directly pathogenic, but they can cause problems if they produce toxins that contaminate water supplies.

Coloration

The color difference in algae is due to different photosynthetic pigments. Green algae use chlorophyll, while other algae have different pigments that give them their color.

🌿 Lichens

Symbiotic Relationship

Lichens are a combination of:

• Green algae or cyanobacteria (photosynthetic organisms)

• Fungus

Appearance

Lichens come in various forms:

• Flat with orange coloration

• Three-dimensional with a leaf-like pattern

• Three-dimensional with stalk-like structures

Role in Soil Production

Lichens contribute to soil production by breaking down rocks and hard substances over a long period, turning them into soil.

Lichens 🍄

Lichens are a symbiotic relationship between a fungus and a photosynthetic organism, such as green algae or cyanobacteria.

Roles of Lichens

• Fix Nitrogen: Lichens convert nitrogen into a form that can be used by various organisms.

• Antibacterial Compounds: Lichens produce antibacterial substances.

• Food Source: In harsh environments like the Arctic, reindeer can consume lichens as a food source.

Controlled Parasitism

Lichens exhibit a type of controlled parasitism where the fungus derives nutrients from the photosynthetic organism. The photosynthetic algae or cyanobacteria would grow better on its own but participates in this symbiotic relationship.

Characteristics

• Slow-growing

• Can live for centuries

• Not pathogenic (do not cause harm)

• Help break down rocks

Lichenometry

Organism Research Activity 🦠

Overview

Students will research two organisms (a bacterium and another category such as algae, fungi, or virus) and answer questions about them.

Instructions

1. Obtain a strip listing two scientific names of organisms.

2. Use the textbook or Wikipedia as primary sources to find information about the organisms.

3. Complete the Google form for each organism, answering questions about:

   • Diseases caused by the organism

   • Natural habitats of the organism

   • Type of organism (bacterium, fungi, algae, helminth, etc.)

Specific Questions for Bacteria

• Gram stain (Gram-positive, Gram-negative, or acid-fast)

• Morphology (shape of individual cells)

• Arrangement of cells

Specific Questions for Helminths

• Phylum (Nematode or Platyhelminth)

Specific Questions for Algae

• Category of algae (brown algae, green algae, red algae, diatom, dinoflagellate, etc.)

Submission

Submit the Google form twice, once for each organism, by the specified deadline.

Parasites 🪱

Trypanosoma brucei 🦠

• Trypanosoma brucei was assigned as one of the parasites to study.

  It is important to know the specific scientific name to identify the assigned parasite correctly.

• For some parasites, there may be a common name that is more widely known.

  • For example, Haemophilus influenzae is the scientific name for what is commonly known as the flu virus.

  • Using online resources like Google or ChatGPT can help to find additional information or clarify if there is a common name for a specific parasite.