Lectures 8- TBD: Exam 2

How is Archaea different from Bacteria?

• Aerobes and Anaerobes

• Autotrophs and Heterotrophs

• Gram-positive and Gram-Negative

• Normally 1 circular chromosome

How is Archaea similar to Bacteria?

• Difference in 16s rRNA sequences

• Lack peptidoglycan

• Chromosomes have histones

• Role as human pathogens (although unclear)

• Extremophiles or Psychrophiles

How do we sort bacteria into Phyla?

• Based on 16s rRNA sequencing; can go down to species

Gram-Positive Phyla

• Firmicutes (Bacillota)

• Actinobacteria (Actinomycetota)

• Tenericutes (Mycoplasmatota)

Features of Gram-Positive Phyla

• Most are chemotrophs

• Can be grouped by DNA’s GC content

• Includes human pathogens

Phylum: Actinobacteria (Actinomycetota)

• Gram-Positive Phyla

• Mostly aerobic and filamentous

• High GC content

Genus: Streptomyces

• Gram-Positive Phylum: Actinobacteria

• Aerobic

• GC Content: 69-73%

• Common in soil to degrade organic material

• Source of common antibiotics

• Forms spores, not endospores

Phylum: Firmicutes (Bacillota)

• Gram-Positive Phylum

• Low GC Content

• Forms endospores

Genus Clostridium

• Gram-Positive Phylum: Firmicutes

• Makes endospores

• Obligate anaerobes

• Common in soil

• Ferment sugars to acetone, butanol, butyric acid, no ETC

• Many human pathogens

- Produce exotoxins

Botulism, tetanus, etc.

_Bacillus

• Gram-Positive Phylum: Firmicutes

• Makes endospores

• Aerobes or Facultative anaerobes

• Chemoheterotrophs

• Motile via peritrichous flagella

• Source of common antibiotics

• few human pathogens

Order: Lactobacillales

• Gram-Positive Phylum: Firmicutes

• Does not form endospores

• Low GC Content

• Lack ETS

• Lactic acid fermentation

• Mostly aerotolerant anaerobes

Genus: Staphylococci

• Gram Positive Phyla; Firmicutes

• Does not form endospores

• Low GC content

• Resistant to drying

• Salt tolerant

• Common microbes

Gram-Negative Phyla

• Proteobacteria

• Bacteroidetes

• Cyanobacteria

What classes are in the phylum Proteobacteria?

• Alphaproteobacteria

• Betaproteobacteria

• Gammaproteobacteria

Class: Alphaproteobacteria: Subclasses

• Rhizobium

• Agrobacterium

• Rickettsia

Phylum: Proteobacteria Class: Alphaproteobacteria Subclass: Rhizobium

• Beneficial symbiosis with legumes (peas/beans)

a. Uses plasmids to initiate root nodules

• Nitrogen-fixation

a. can reduce N2 to NH4+ ammonia

b. only exists in a few species

requires a lot of ATP

Phylum: Proteobacteria Class: Alphaproteobacteria Subclass: Agrobacterium

• Closely related to Rhizobium

• Harmful symbiosis with plants

a. Uses plasmids to cause tumors

• Plasmids used in plant genetic engineering

Phylum: Proteobacteria Class: Alphaproteobacteria Subclass: Rickettsia

• Aerobic organotrophs

• Some can only oxidize intermediate metabolites (glutamate)

• Includes intracellular parasites of vertebrates

a. vectored via arthropods

b. human diseases

c. multiply in host (and lyse) phagocytes

Phylum: Proteobacteria Class: Betaproteobacteria

Neisseria

• shape: cocci

• aerobic

• no flagella

• pathogenic

• colonize warm-blooded animals

Phylum: Proteobacteria Class: Gammaproteobacteria - Enteric Proteobacteria

• Rod-shaped

• mostly motile via peritrichous flagella

• Faculative anaerobes

a. Aerobic respiration

b. Anaerobic respiration

c. Can also do fermentation

• Mixed acid fermentation

• 2,3 butanediol fermentation

What genera perform mixed-acid fermentation?

• Escherichia

• Shigella

• Salmonella

What genera perform 2,3 butanediol fermentation?

• Enterobacter

• Klebsiella

Phylum: Proteobacteria Class: Gammaproteobacteria - The Pseudomonads

• Straight or curved rods

• Polar flagella

• Chemoheterotrophs

• Use the Entner-Doudroff pathway

a. aerobic respiraton

b. incapable of fermentation

• Pathogens of animals and plants

• Can grow at low temperatures and cause food spoilage

Phylum: Bacteroidetes

• Diverse, no unifying phenotypic features

• Bacteroides

  • Obligate anaerobes

  • most numerous microbe in human gut

  • ferment undigested food

    • lactate, acetate

• Some are pathogenic, cause peritonitis

Phylum: Cyanobacteria

• Only prokaryotes that can do oxgenic photosynthesis

• Contain thylakoids

• increase O2 content of ancient Earth

• Can fix nitrogen

• Cause algal blooms in phosphate rich water

Plants vs. Fungi

Plants

• cellulose cell walls

• autotrophic

• phototrophic

Fungi

• chitin cell walls

• heterotrophic

• chemotrophic

Bacteria vs. Fungi

Bacteria

• Prokaryotes

• Peptidoglycan cell walls

Fungi

• Eukaryotes

• Chitin cell walls

Common Fungi Morphology

• Some are single celled (yeast)

• Some are multicellular

  • molds

  • mushrooms

• Most do not have flagella

• Reach nutrients by

  • Spore dispersal (wind)

  • Hyphae growth

    • Thin filaments

    • grow at the tip

Dimorphic fungi

• Switch between single and multicellular forms

Fungal Hyphae

• Sent out during germination

• Hyphae….

  • use tip growth to lengthen in the environment

  • focus on length rather than width

  • Can branch

  • mass = mycelia

• Septa; cross walls, may have pores. Only some hyphae

• Coenocytic = multiple nuclei within a single cytoplasm (no septa hyphae)

Fungal Nutrition

• Saprobes

  • Extract nutrients from dead tissues

  • secrete enzymes to break down molecules

  • digested nutrient absorbed by hyphae

• Most are aerobes (some facultative anaerobes)

• Most store carbohydrates as glycogen

Fungal Phyla

• Glomeromycota

• Ascomycota

• Basidiomycota

Based on rRNA sequencing

Fungal Spores

• non—motile reproductive cells

• dispersed by wind or animals

• not as strong as endospores, but can resist environmental stress

• may become airborne via fruiting bodies that are developed by hyphae

Ascomycota

• Sac fungi

  • yeast, molds, morels, truffles, cup fungi

• Ascus: sac-like sexual structure that produces haploid spores called Ascospores

• Half are symbionts

• many common plant pathogens

Phylum Ascomycota: Asexual Reproduction

• Most common mode of reproduction and occurs under favorable conditions

Yeast:

• Budding, mitosis splits nuclei, daughter cell

Multicellular:

• Condiospores: specialized hyphae that produce conidia (mitospores)

Phylum Ascomycota: Sexual Reproduction

• Occurs under nutrient limited conditions

Yeast:

• haploid spores produced from meiosis

Multicellular:

• formation of ascospores via meiosis

• hyphae from + and - strains fuse cytoplasm, cause ascospore formation

Basidiomycota

• “Club Fungi”

  • Includes yeasts, true mushrooms, puffballs, bracket fungi

  • Breaks down plant/wood material

Basidiomycota: sexual reproduction

• Multicellular forms:

  • hyphae fuse cytoplasms

  • nuclei pairdo not fuse, but becomea structure called dikaryon

  • clamp connection

  • grows into basidiocarp, nuclei fuse after and undergo meiosis, producing haploid basidiospores that can be dispersed by the wind

Traits of The Protista

• Eukaryotes

• Most are single-celled, some multicellular

• Some motile, some not

• grouped by common traits

Algae

• Come in single cell and multicellular forma

• Have chlorophyll

• Use oxygenic photosynthesis

• Autotrophs that use CO2 or HCO3

• Cellulose cell wall

• some have flagella, none have cilia

Algae includes…..

• Euglenophytes

• Dinoflagellates

• Diatoms

• Chlorophytes (Green Algae)

• Phaeophytes (Brown Algae)

• Rhodophytes (Red Algae)

DOES NOT INCLUDE CYANOBACTERIA

Protozoa

• Most are free-living, some are important symbionts

• Most live in aquatic systems, some in moist soil

• Some have contractile vacuoles (pumps water out using osmotic pressure)

• Most are heterotrophs

• Most capable of movement

Protozoa includes…

• Zooflagellates

• Amoebas

• Ciliates

• Sporozoans

The Oomycetes

• Related to diatoms and brown algae, NOT FUNGI

• Have hyphae

• Cellulose Cell walls

• Important decomposers in freshwater ecosystems

• animal and plants parasites

Plasmodal Slime Molds

• Spores that germinate into a haploid cells that can fuse into Diploid cells

• Diploids divide nucleus without cell division forming a plasmodium

• Fruiting bodies develop for sexual reproduction

  • Produce haploid spores

Plasmodium

• A membrane bound mass of cytoplasm with multiple nuclei

• Can be centimeters long

• Move like an Amoeba

• Fruiting bodies develop for sexual reproduction

  • Produce haploid spores

Cellular Slime Molds

• Starts off as spores, germinates into a haploid cells

• Limited nutrients: cells aggregate into slug-like blobs called pseudo-plasmodium

• Produces haploid spores

Pseudo-plasmodium

• Resembles plasmodia but composed of multiple cells.

• Fruiting bodies develop for asexual reproduction.

• Can also reproduce sexually via diploid spores