Microbiology: Fungal Infections and Bacteria

Mycosis

• Fungal infections
• Opportunistic mycoses are caused by fungi that are harmless in their natural habitat but become pathogenic in a compromised host.
• Zombie ant fungus (Cordyceps and Ophiocordyceps unilateralis) is an insect pathogen that exhibits mind control.
• Chondrostereum purpureum is a plant fungus that infected a human in 2023.
• Morphological characteristics are useful for identifying eukaryotes, but tell little about phylogenetic relationships.

Archaea classification

• Archaea are a distinct taxonomic grouping.
• They lack peptidoglycan.

Spirochaetes

• Cause syphilis and Lyme disease.

Proteobacteria

• Gram-Negative

Alphaproteobacteria

• A class under the Proteobacteria phylum.
• Includes Ehrlichia, Agrobacterium, and Rickettsia.

Gammaproteobacteria

• A class under the Proteobacteria phylum.
• Includes Vibrio, Salmonella, Helicobacter, and Escherichia.

Bacilli (Endospores)

• Belongs to the Firmicutes phylum.

Bacilli (Clostridia)

• Gram-Positive
• Belongs to the Firmicutes phylum.

Lactobacillales

• Gram-Positive
• Belongs to the Firmicutes phylum.

Subgroups of Lactobacillales

• Gram-Positive
• Staphylococcus
• Streptococcus

Actinobacteria

• Gram-Positive

Bacteroidetes

• Gram-Negative
• Many opportunistic pathogens.

Heterotrophic organisms

• Gain nutrients through absorption.

Saprophytic

• Feed on dead matter.

Filamentous fungi

• Include molds and fleshy fungi.

Organ Transplants

• Tolypocladium inflatum produces cyclosporine, which helps suppress the immune system and is used in organ transplant patients.

Salem Witch Trials

• Mostly started due to erratic behavior after consuming rye products with ergot fungus growing on them in 1692.

Ascomycota

• Ascospores are produced sexually.
• Nuclei morphologically similar or dissimilar fuse in a saclike ascus.

Lichens

• Economic importance:
  • Dyes
  • Antimicrobial (Usnea)
  • Litmus
  • Food for herbivores

Paecilomyces

• Kills termites.

Trichoderma

• Produces cellulase.

Saccharomyces cerevisiae

• Used in bread, wine, and hepatitis B vaccine production.

Brown Algae

• Cellulose and alginic acid cell walls.
• Multicellular and macroscopic.
• Produce algin, a thickener used in foods.

Red Algae

• Have branched thalli.
• Most are multicellular.
• Harvested for agar and carrageenan.
• Some produce a lethal toxin.

Green Algae

• Cellulose cell walls.
• Unicellular or multicellular.
• Chlorophyll a and b.
• Store starch.
• Gave rise to terrestrial plants.

Diatoms

• Produce domoic acid, which can cause neurological disease.
• Can be contracted by swimming in saltwater affected by algal blooms.

Protista

• Catchall kingdom for diverse eukaryotic organisms.
• Clades are groups based on rRNA genetic similarities.
• Protists are eukaryotes excluding fungi, animals, and plants.
• Algae are photosynthesizing protists, not a formal taxonomic group.
• Green algae gave rise to terrestrial plants and store starch.
• Diatoms are unicellular algae with silica cell walls and store oil.
• Oomycota are water molds, decomposers related to brown algae.
• Trophozoite is the feeding and growing form of protozoa.
• Uncoating is the process where viral or host enzymes release viral components.
• Crustacea have four antennae.

Archaea

• A domain of prokaryotes, often extremophiles.

Morphological Characteristics

• Physical traits used for identifying eukaryotes.

Differential Staining

• Techniques like Gram staining used to classify bacteria.

Biochemical Tests

• Tests that determine the presence of bacterial enzymes.

Culture

• Bacteria grown in laboratory media.

Clone

• Population derived from a single parent cell.

Variant

• A slight genetic difference without functional change.

Strain

• Accumulated genetic differences affecting behavior.

Viral Species

• Population of viruses occupying a specific niche.

Halophiles

• Require salt concentration greater than 25%.

Thermophiles

• Require growth temperature over 80°C.

Gram Positive Bacteria

• Have a thick peptidoglycan cell wall and stain purple.

Gram Negative Bacteria

• Have a thin peptidoglycan wall and stain pink.

Endospores

• Resistant structures formed by certain bacteria.

Endosymbiotic Theory

• A proto-eukaryote engulfed a protomitochondrion.

Protista

• A catchall kingdom for a variety of organisms; autotrophic and heterotrophic.

Fungi

• Chemoheterotrophic; unicellular or multicellular; cell walls of chitin; develop from spores or hyphal fragments.

Plantae

• Multicellular; cellulose cell walls; undergo photosynthesis.

Animalia

• Multicellular; no cell walls; chemoheterotrophic.

Mycology

• The study of fungi.

Hyphae

• Filaments that make up the fungal thallus (body).

Mycelium

• A mass of hyphae.

Septate hyphae

• Hyphae that contain cross-walls.

Coenocytic hyphae

• Hyphae that do not contain septa.

Fungal lifecycle

• Fungi reproduce sexually and asexually via the formation of spores.