Unit 2 Exam Study Guide

Habitats for Prokaryotes

Ubiquitous; hot springs, ice caps, deep ocean, skin & mucosal surfaces

Characteristic of Prokaryotes

Adaptable and resilient; ability to switch metabolic or respiration method

Function of Prokaryotes

Stability of Ecosystems, Carbon and Nitrogen Fixation, Environmental cleanup, Human pathogens, Climate change

Mutualism

Benefitted, Benefitted (Gut nutrient metabolism)

Amensalism

Harmed, unaffected (Antimicrobial defense on skin)

Commensalism

Benefitted, Unaffected (skin cells as food source)

Neutralism

Unaffected, unaffected

Parasitism

Benefitted, Harmed

Microbial Ecology

-Many live in communities (polymicrobial)
- Cooperative (biofilm formation)
- Competing (scarce resources)

Microbiome

Prokaryotes + Eukaryote Microbes
- Resident
- Transient

How do microbiomes differ?

Between different sites & organisms

Do Prokaryotes Reproduce Sexually?

No

Best Approach to Prokaryotes

Molecular, biochemical, microscopy, and nucleotide sequences together

Bergey's Manual of Systematic Bacteriology

Standard for bacterial taxonomy

American Type Culture Collection

largest collection of microbes available

Gram Negative Phyla

Proteobacteria, Spirochete, CFB group, Planctomycetes, Phototrophic Bacteria

Gram Positive Phyla

Actinobacteria, Firmicutes

Atypical

Tenericutes

Alphaproteobacteria

- Prominent genera include chlamydia & Rickettsia - Obligate intracellular and must have host to be metabolically active

Oligotrophs

living in low nutrient environments

Rickettsia spp.

causative agents for Rocky mountain spotted fever & typhus fevers

Chlamydia spp.

Causative agents for lymphogranuloma venereum (STD)

Betaproteobacteria

Prominent genera include Bordetella & Neisseria

Eutrophs

require many nutrients (copiotrophs)

Bordetella spp.

Causative agents whooping cough (pertussis) & kennel cough
- Produces toxins to paralyze lung cilia

Neisseria gonorrhea

causative agent for gonorrhea STD

Neisseria meningitides

causative agent for bacterial meningitis

Class: Gammaproteobacteria

Most diverse
- Prominent genera: Pseudomonas, Pasteurella, Haemophilus, Vibrio, Legionella, Enterobacter family

Pseudomonas aeruginosa

common infection of wounds, urinary tract, and respiratory tract

Pasteurella haemolytica

causative agent for severe pneumonia in animals

Haemophilus influenza

causative agent for upper & lower respiratory infection (does not cause influenza)

Vibrio spp.

commonly found in alkaline environments such as ocean ports & lagoons
- gastrointestinal disease, cellulitis, blood-borne infections

Vibrio cholera

causative agent of cholera and common to water contamination

Legionella pneumophila

causative agent for Legionnaire's disease and common to water contamination

Enterobacter family

includes E.coli & Salmonella spp.

Coliforms

E.coli- like; microbes that ferment lactose completely

Noncoliforms

fermentation of lactose is incomplete or absent

E.coli

most mutalistic, some produce shiga toxin

Salmonella

multiple serotypes, cause salmonellosis

Deltaproteobacteria

Relatively small class
Sulfate reducing bacteria
Parasitic Bdellovibrio spp.

Desulfovibrio orale

periodontal disease

Soil dwelling Myxobacteria

slime bacteria

Class Epsilonproteobacteria

Smallest class, microaerophilic
Prominent genera: Campylobacter & Heliobacter

Campylobacter spp.

common to food poisoning

Helicobacter spp.

commonly beneficial but can cause ulcers and stomach cancer in susceptible people

Spirochetes

- Gram (-) extremely thin and hard to stain & culture
- have axial filament similar to flagella

Treponema Pallidum

Causative agent for syphilis

Borrelia burgdorferi

Lyme disease

Cytophaga spp.

Gliding system for motility (mechanisms mostly unknown)

Fusobacteria spp.

inhabit mouth and can cause various oral diseases

Bacteroides spp.

30% of gut microbiome; lower levels correlated with obesity

CFB Group

Cytophaga, Fusobacterium, Bacteroides

Planctomycetes

- Found in aquatic environments; fresh, salt, and brackish
- Reproduce via budding instead of binary fission

Sessile Cells

immobile with holdfast appendage (a)

Swarmer cells

motile, unable to reproduce

Phototrophic Bacteria

Utilize sunlight as main source of energy via photosynthesis
- Contains proteo & non-proteobacteria
Major groups: purple & green bacteria due to "bacteriochlorophulls" & cyanobacteria

Oxygenic

produce o2

Anoxygenic

do not produce o2

Cyanobacteria

highly adaptable and diverse; chlorophyll; uses as biosorbents and human nutrition

Microsystis spp.

toxic algal blooms

Purple sulfur bacteria

oxidize hydrogen sulfide to elemental sulfur & sulfuric acid

Purple non-sulfur bacteria

use only hydrogen

Green sulfur bacteria

oxidize sulfide

Green non-sulfur bacteria

oxidize non-sulfide substrates

Gram-positive Bacteria

Stains gram (+) purple
- Grouping by guanine + cytosine content
- Phylum Actinobacteria \= high G+C content (\>50%)
- Phylum Firmicutes \= low G+C content (

Actinobacteria phylum

- Extremely diverse
- Thin, filamentous to coccobacilli shaped
- Important to soil ecology
- Different peptidoglycans in cell walls
Prominent Genera include: Mycobacterium, Corynebacterium, Bifidobacterium, Gardnerella

Mycobacterium spp.

Acid fast (+) due to mycolic acid in cell wall
- causative agent for tuberculosis & leprosy

Corynebacterium spp.

Diaminopimelic acids in cell wall
- Most are non-pathogenic; C. diphtheria is causative agent for diphtheria

Bifidobacterium spp.

Filamentous & anaerobic
- Frequently used as probiotic

Gardnerella vaginalis

- Only one species
- Gram variable: inconsistent stain results
- Causative agent for bacterial vaginosis

Firmicutes phylum

- Low G+C content
- No other common characteristic
Prominent Genera:
Clostridium, Lactobacillales (Streptococcus, Lactobacillus, Enterococcus), Bacilli (Bacillus, Staphylococcus)

Genus Clostridium

mostly obligate anaerobes
- Endospore producers
- Soil Dwelling
- Common food contaminant

C. perfringens

agent for food poisoning and gangrene

C. tetani

producer of neurotoxin and agent for tetanus

C. Botulinum

producer of botulinum neurotoxin

C. Difficile

hospital infection, cause severe colitis

Order Lactobacillales

contain bacilli & cocci

S. pyogenes

B-hemolytic cocci associated with pus production, strep throat

S. pneumoniae

causes pneumonia, respiratory infections, and a wide range of other diseases

Lactobacillus

-Facultative anaerobes
- Non spore formers
- Significant component of gut microbiome
- Start cultures for yogurt, cheese, sauerkraut, etc.

Enterococcus

- Diplicocci arrangement
- Anaerobic respiration
- Commensal gut microbe
- Common UTI pathogen (E.faecium)

Genus Bacillus

bacillus shaped aerobes or facultative anaerobes
- Endospore producers
- Important to industrial microbiology

B. anthracis

causative agent for anthrax

B. cereus

common food poisoning agent

B. thuringiensis

producer of insecticide compounds

Genus Staphylococcus

cocci shaped facultative anaerobes (Halophilic, Nonmotile)

S. aureus

common agent of skin infections; some can produce enterotoxins for food poisoning; Some are very antibiotic resistant (MRSA & VRSA)

S. epidermidis

common flora on skin; can cause infection to open wounds

Genus Mycoplasma

no cell wall and do not retain crystal violet
- pleomorphic
- Extremely small
- Cell wall antibiotics do not work
- Only classified by genome

M. pneumoniae

agent for walking pneumonia

Deeply branching bacteria

Genera and species that are most common to the last universal common ancestor (LUCA)
- Provides clues to structure and function of ancient forms of life
- Prominent classes: Aquificae, Thermotogae, Deinococci

Aquificae

gram (-) hyperthermophiles living in hot springs and oven vents

Thermotogae

gram (-), hyperthermophilic anaerobes; sheath-like outer membrane

Deinococci

gram (+) polyextremophile (heat, vacuum, acidity tolerant)

Archaea

Distinguished by:
- Membranes with branched isoprene chains & ether linkages to phosphate head
- Walls of surface layer proteins (some pseudopeptidoglcan
- Genomes are much larger
- Capable of methanogenesis
- Usually not in human microbiota
- Not directly associated with infectious diseases

Phylum Crenarchaeota

- All aquatic microbes, many extremophiles
Prominent genera: Sulfolobus spp., Thermoproteus spp.

Sulfolobus spp.

thermophiles & acidophiles; facultative anaerobic; used in biotech for production of affitins

Thermoproteus spp.

strict anaerobic thermophiles; arguably deepest branching Archaea

Phylum Euryarchaeota

mostly methanogens & anaerobes
Prominent classes include methanobacteria, methanococci, methanomicrobia, Halobacteria ("salt-loving")

Eukaryotic microbes

Extremely diverse
- Different life cycles & reproduction modes
- Many morphologically specialized structures
- Specialized nutritional needs