Microbiology Chapter 11: The Prokaryotes (Domains Bacteria and Archaea)

Vocabulary practice flashcards covering prokaryotic taxonomy, phyla, notable genera, diagnostic features, and physiological characteristics of Bacteria and Archaea from Chapter 11.

Proteobacteria

The largest taxonomic group of bacteria, consisting of gram-negative, chemoheterotrophic species across five distinct classes, named after the Greek god Proteus.

Prosthecae

Stalks or buds extending from certain alphaproteobacterial cells (such as Caulobacter and Hyphomicrobium) that facilitate attachment and nutrient uptake in low-nutrient environments.

Pelagibacter

An extremely small genus of Alphaproteobacteria that is among the most abundant microorganisms in the oceans and plays an essential role in Earth's carbon cycle.

Azospirillum

A genus of soil-dwelling Alphaproteobacteria that forms close associations with plant roots, feeds on plant excretions, and fixes atmospheric nitrogen.

Acetobacteraceae and Gluconobacter

Alphaproteobacteria that industrially convert ethanol into acetic acid (vinegar).

Rickettsia

A genus of obligate intracellular parasitic Alphaproteobacteria transmitted by insect and tick bites that cause spotted fevers, including R. prowazekii (epidemic typhus), R. typhi (endemic murine typhus), and R. rickettsii (Rocky Mountain spotted fever).

Ehrlichia

A genus of Alphaproteobacteria that is transmitted to humans by tick bites and causes ehrlichiosis.

Caulobacter

A stalked alphaproteobacterium adapted to low-nutrient aquatic habitats that divides asymmetrically into a stationary stalked cell and a mobile flagellated swarmer cell.

Hyphomicrobium

A genus of budding, prosthecate Alphaproteobacteria found in low-nutrient aquatic environments that reproduces by forming buds at the tips of hypha-like extensions rather than by binary fission.

Rhizobia (Rhizobium and Bradyrhizobium)

Symbiotic alphaproteobacteria that infect and inhabit root nodules of leguminous plants to fix atmospheric nitrogen.

Crown Gall Disease

A plant tumor condition induced when the bacterium Agrobacterium inserts a plasmid containing tumor-inducing genes into plant cells.

Bartonella henselae

A pathogenic alphaproteobacterium that causes cat-scratch disease in humans.

Brucella

An obligate intracellular mammal parasite of the Alphaproteobacteria that is capable of surviving phagocytosis and causes brucellosis.

Nitrosomonas

A chemoautotrophic genus of nitrifying bacteria that oxidizes ammonium to nitrite: $\text{NH}_4^+ \rightarrow \text{NO}_2^-$.

Nitrobacter

A chemoautotrophic alphaproteobacterium that oxidizes nitrite to nitrate: $\text{NO}_2^- \rightarrow \text{NO}_3^-$.

Wolbachia

An endosymbiont genus of Alphaproteobacteria that infects insects and manipulates host reproductive mechanisms.

Acidithiobacillus

A chemoautotrophic betaproteobacterium that obtains energy by oxidizing sulfur and hydrogen sulfide into sulfates: $\text{H}_2\text{S} \rightarrow \text{SO}_4^{2-}$.

Spirillum

A helical, freshwater-dwelling genus of Betaproteobacteria that moves via polar flagella.

Sphaerotilus

A freshwater and sewage betaproteobacterium that forms hollow tubular sheaths around chained cells for protection and nutrient accumulation.

Burkholderia cepacia

A nutritionally versatile betaproteobacterium capable of degrading more than 100 different organic molecules, occasionally causing opportunistic hospital infections.

Bordetella pertussis

A non-motile, rod-shaped betaproteobacterium responsible for causing whooping cough.

Neisseria

A genus of gram-negative diplococci within Betaproteobacteria, including N. gonorrhoeae (cause of gonorrhea) and N. meningitidis (cause of meningococcal meningitis).

Zoogloea

A betaproteobacterial genus that produces gelatinous masses vital to the purification process in sewage activated sludge systems.

Beggiatoa

A genus in the order Thiotrichales (Gammaproteobacteria) that inhabits aquatic sediments and chemoautotrophically oxidizes hydrogen sulfide to elemental sulfur: $\text{H}_2\text{S} \rightarrow \text{S}^0$.

Francisella tularensis

A pleomorphic pathogenic gammaproteobacterium in the order Thiotrichales that causes tularemia.

Pseudomonas aeruginosa

A metabolically diverse gammaproteobacterium with polar flagella that is common in soil and acts as an opportunistic pathogen causing wound and urinary tract infections.

Moraxella lacunata

An aerobic gammaproteobacterium belonging to Pseudomonadales that causes human conjunctivitis.

Acinetobacter baumanii

An opportunistic respiratory pathogen in the order Pseudomonadales recognized for widespread resistance to antibiotics.

Legionella

A genus of Gammaproteobacteria found in natural streams, cooling towers, and warm-water distribution systems that causes legionellosis.

Coxiella burnetii

The gammaproteobacterial causative agent of Q fever, transmitted via milk or aerosols and distinguished by possessing an endospore-like body that provides physical resistance.

Vibrio cholerae

A slightly curved rod in the order Vibrionales that inhabits aquatic environments and produces cholera toxin, causing profuse watery diarrhea.

Enterobacteriales (Enterics)

A group of facultatively anaerobic, peritrichously flagellated Gammaproteobacteria that inhabit the intestinal tracts of animals and ferment carbohydrates.

Escherichia coli

A primary enteric bacterium that serves as an indicator organism for fecal contamination and causes foodborne illnesses and urinary tract infections.

Salmonella

A genus of enterics with over 2,500 distinct serovars that represents a frequent cause of foodborne illness; includes S. typhi, the agent of typhoid fever.

Proteus mirabilis

An enteric rod that exhibits swarming motility with peritrichous flagella, creating distinct concentric growth rings on culture plates.

Yersinia pestis

The enteric bacterium that causes plague, transmitted between hosts primarily via flea bites.

Cronobacter sakazakii

An enteric bacterium discovered in 2007 that can contaminate baby formula and various dry foods, causing neonatal meningitis.

Haemophilus

A genus in Pasteurellales that requires X factor (heme) and V factor ($\text{NAD}^+$, $\text{NADP}^+$) to grow; includes H. influenzae, which causes meningitis, earaches, and epiglottitis.

Bdellovibrio bacteriovorus

A predatory deltaproteobacterium that attacks, penetrates, and replicates within other gram-negative bacteria.

Desulfovibrio

An obligately anaerobic deltaproteobacterium found in sediments and intestinal tracts that utilizes $\text{S}^0$ or $\text{SO}_4^{2-}$ as terminal electron acceptors in place of oxygen.

Myxococcales

An order of deltaproteobacteria known as slime bacteria that glide along slime trails and aggregate under nutrient depletion to form multicellular fruiting bodies producing resistant myxospores.

Campylobacter jejuni

A microaerophilic, curved Epsilonproteobacterium bearing a single polar flagellum that serves as a common cause of foodborne intestinal illness.

Helicobacter pylori

A microaerophilic, curved rod with multiple flagella that colonizes the human stomach, leading to peptic ulcers and stomach cancer.

Heterocysts

Specialized, thick-walled cells found in filamentous cyanobacteria that maintain an anaerobic interior dedicated to nitrogen fixation.

Cyanobacteria

Gram-negative, oxygenic photosynthetic bacteria carrying out the reaction $2\text{H}_2\text{O} + \text{CO}_2 \xrightarrow{\text{light}} (\text{CH}_2\text{O}) + \text{H}_2\text{O} + \text{O}_2$, often containing gas vesicles for buoyancy.

Anoxygenic Photosynthesis

Bacterial photosynthesis that does not generate molecular oxygen, utilizing hydrogen sulfide or organic compounds as electron donors: $2\text{H}_2\text{S} + \text{CO}_2 \xrightarrow{\text{light}} (\text{CH}_2\text{O}) + \text{H}_2\text{O} + 2\text{S}^0$.

Chlorobi

A phylum of anoxygenic photosynthetic green sulfur bacteria (such as Chlorobium) that deposit sulfur granules inside cells and use $\text{H}_2\text{S}$ as an electron donor.

Chloroflexi

A phylum of anoxygenic photosynthetic green nonsulfur bacteria (such as Chloroflexus) that grow filamentous chains and utilize organic compounds as electron donors.

Elementary Body

The small, dense, extracellular infectious stage of chlamydiae that binds to host cells to initiate infection.

Reticulate Body

The larger, metabolically active, intracellular reproductive stage of chlamydiae that divides successively inside host cell vacuoles.

Gemmata obscuriglobus

A planctomycete bacterium that possesses a double membrane enclosing its nucleoid DNA, structurally resembling a eukaryotic cell nucleus.

Bacteroides

An anaerobic genus in the phylum Bacteroidetes that constitutes a substantial percentage of the normal human microbiota in the oral cavity and large intestine.

Fusobacterium

A genus of obligately anaerobic, pointed spindle-shaped bacteria found in the mouth that can cause dental abscesses and tissue necrosis.

Axial Filaments (Endoflagella)

Bundles of fibrils running between the cell body and external sheath of spirochetes that rotate to drive corkscrew motility.

Deinococcus radiodurans

An exceptionally hardy bacterium capable of surviving exposure to ionizing radiation levels greater than those tolerated by bacterial endospores.

Thermus aquaticus

A thermophilic bacterium originally isolated from a hot spring in Yellowstone National Park that serves as the source of heat-tolerant Taq polymerase.

Firmicutes

A major phylum of gram-positive bacteria defined by low $\text{G} + \text{C}$ base ratios, encompassing classes Bacilli and Clostridia.

Clostridium

An endospore-producing genus of obligate anaerobes in Firmicutes, including C. tetani, C. botulinum, C. perfringens, and C. difficile.

Epulopiscium fishelsoni

A giant gram-positive bacterium large enough to be seen with the unaided eye that gives birth to multiple daughter cells internally rather than dividing by binary fission.

Parasporal Body

A protein crystal formed alongside the endospore in Bacillus thuringiensis that acts as a potent toxin against insects upon ingestion.

Staphylococcus aureus

A low $\text{G} + \text{C}$ gram-positive coccus that clusters in grapelike arrangements, produces enterotoxins, and is a frequent cause of skin and surgical wound infections.

Beta-hemolytic Streptococci

Streptococci (such as Streptococcus pyogenes and S. agalactiae) that produce enzymes causing complete lysis of red blood cells on blood agar plates.

Mycoplasma

A genus of Tenericutes characterized by the complete absence of a peptidoglycan cell wall and marked pleomorphism, including M. pneumoniae.

Actinobacteria

A phylum of gram-positive bacteria possessing high $\text{G} + \text{C}$ genomic ratios, commonly displaying pleomorphic shapes or branching filaments in soil.

Mycobacterium

An actinobacterial genus featuring an outer layer of waxy, water-resistant mycolic acids in its cell wall, including slow-growing pathogens M. tuberculosis and M. leprae.

Streptomyces

A soil-dwelling genus of Actinobacteria with reproductive conidiospores borne on branching hyphae that produces the majority of commercial antibiotics.

Frankia

A high $\text{G} + \text{C}$ actinobacterium that induces nitrogen-fixing nodules on the roots of certain non-leguminous woody plants.

Halophiles

Extremophilic archaea that require high salt concentrations greater than $25\%$ to grow, frequently populating solar evaporating ponds.

Thermophiles (Archaea)

Extremophilic archaea requiring growth temperatures higher than $80^\circ\text{C}$.

Methanogens

Strictly anaerobic archaea (such as Methanobacteria) that produce methane gas as an end product of metabolism.

Thiomargarita namibiensis

A giant sulfur-oxidizing marine bacterium reaching diameters up to $750\,\mu\text{m}$.

Carsonella ruddii

An endosymbiotic insect-associated bacterium possessing one of the smallest known bacterial genomes, coding for only 182 genes.