bacteria to know more about

Question 1

Rhizobium

Answer 1

Gram negative, Alphaproteobacteria
Ag. important bacteria in that infects the legumes of roots
Presence of rhizobia results in nodules forming on the roots
Symbiotic relationship; fixes nitrogen (N2 + 3H2 -> 2NH3)

Question 2

Agrobacterium

Answer 2

Gram negative, Alphaproteobacteria
Plant pathogen; like rhizobia it can invade plant cells, but in this case they don’t fix nitrogen or cause nodules
Uses horizontal gene transfer to cause tumors in plants -> contain plasmids that randomly integrate into the plants genome, then tumor genes are expressed causing the formation of tumors [gall]
Agrobacterium tumefaciens causes Crown gall disease

Question 3

Rickettsia

Answer 3

Gram negative, Alphaproteobacteria
Coccobacilli shaped
Obligate intracellular parasite -> reproduce only in mammalian cells
Transmitted to humans by insect bites
Enter by phagocytosis and quickly multiply in the host cell
Rickettsia rickettsii is the causative agent of rocky mountain spotted fever [ticks]

Question 4

Caulobacter

Answer 4

Gram negative, Alphaproteobacteria
Found in low nutrient aquatic environments like lakes; exposed to continuous flow of water
Have stalks that anchor organism to surfaces -> increase chance of getting nutrients
Divide by budding

Question 5

Nitrobacter and Nitrosomes

Answer 5

Gram negative, Alphaproteobacteria; NITROGEN FIXING BACTERIA
Free living, nitrifying bacteria; Highly motile in soil
Chemoautotrophs– use inorganic chemicals as source of energy and CO2 as source of carbon from which they make their nutrients they need to grow
Crucial component of the nitrogen cycle
Easily absorbed; Synergistically promote uptake of other cations

Question 6

Sphaerotilus

Answer 6

Gram negative, Betaproteobacteria
Filamentous bacteria covered in a tubular sheathe
Found in flowing water and sewage and waste water treatment plants -> Can cause clogged pipes
Polar flagella
Not pathogenic

Question 7

Aquifex pyrophilus

Answer 7

Deeply branched bacteria
Thrives near underwater volcanoes and thermal ocean vents, where the temperature of water (under high pressure) can reach 138 °C
Rod shaped bacteria (bacilli)
Uses oxygen in respiration – making H2O but can also grow anaerobically using Nitrogen as the ultimate electron acceptor
Chemoautotroph, Hyperthermophilic (85-95)

Question 8

Deinococcus radiodurans

Answer 8

Deeply branching bacteria
“Conan the Bacterium”, “World’s Strongest Bacteria” -> polyextremophile (heat, drought, acidity, radiation, etc.)
Diverse environments. -> elephant dung to granite slabs in Antarctica
Special ability attributed to unique mechanisms for DNA repair
Tetras
High radiation resistance
Outer membrane similar to gram negative, stains gram positive

Question 9

Pseudomonas

Answer 9

Gram negative, Gammaproteobacteria
Aerobic, rod shaped, motile with polar flagella
Very large genomes [almost as much as yeast]
Pigment formation [fluorescent pigments]
Common in soil
Large variety of enzymes enables them to grow on minute traces of unusual carbons
Can grow on soaps and antiseptics
Resistant to a number of antibiotics -> Porins in the cell wall that can control the entrance of
molecules; Efflux pumps to eject antibiotics
Opportunistic pathogens – cause UTI and wound infections

Question 10

Legionella

Answer 10

Gram negative, Gammaproteobacteria
Intracellular pathogen
Naturally found in streams -> can infect hospital water supplies and coolers
Can survive and reproduce in aquatic amoeba
Causes legionnaire disease [type of pneumonia]
Not transferable from person to person

Question 11

Escherichia

Answer 11

Gram negative, Gammaproteobacteria, Enterobacteriales (Enterics)
Most common inhabitant of the human gut
Presence in water and food is an indication of fecal contamination
Not usually pathogenic
• Can cause UTI
• Certain strains are the cause of travelers diarrhea
• E. coli 0157 very serious food poisoning

Question 12

Salmonella

Answer 12

Gram negative, Gammaproteobacteria, Enterobacteriales (Enterics)
All the members of this genus are potentially pathogenic
Cause of Salmonellosis

Question 13

Shiaellea

Answer 13

Gram negative, Gammaproteobacteria, Enterobacteriales (Enterics)
Nonspore forming, nonmotile
Life threatening dysentery also called shigellosis; Diarreah- often bloody, with fever and cramps (due to toxins produced by organism)

Question 14

Klebsiella

Answer 14

Gram negative, Gammaproteobacteria, Enterobacteriales (Enterics)
Commonly found in soil and water
Many isolates can fix nitrogen
Occasionally causes a serious form of pneumonia

Question 15

Yersinia

Answer 15

Gram negative, Gammaproteobacteria, Enterobacteriales (Enterics)
Nonmotile, coccobacilli
Yersinia pestis – Bubonic plaque

Question 16

Proteus

Answer 16

Gram negative, Gammaproteobacteria, Enterobacteriales (Enterics)
Swarm on agar plates -> Swarmer cells with many flagella move outwards on the edges of the colony and then revert to normal cells with reduced motility
Causes UTI particular in patients with long term catheterization.

Question 17

Serratia

Answer 17

Gram negative, Gammaproteobacteria, Enterobacteriales (Enterics)
Produces red pigment at 25˚
Can be found in catheters & irrigation solutions -> causes urinary and respiratory tract infection in hospitals

Question 18

Bdellvibrio

Answer 18

Gram negative, Deltaproteobacteria
Attaches and penetrates outer membrane of other gram-negative bacteria and reproduces in the
periplasm

Question 19

Myxobacteria

Answer 19

Gram negative, Deltaproteobacteria
Vegetative cells glide leaving behind a slime trail
They digest bacteria they encounter
In low nutrient conditions they aggregate, forming a mound and then differentiate into a fruiting body and produce spores

Question 20

Cyanobacteria

Answer 20

Gram negative, non-proteobacteria
Blue green pigmentation
Photosynthesis; many capable of fixing atmospheric Nitrogen [N2] (this occurs in specialized cells called heterocyst that contain the necessary enzymes)
Unicellular, to colonial, to filamentous
Filamentous form exhibit some cellular differentiation

Question 21

Green sulfur bacteria and green non-sulfur bacteria

Answer 21

Gram negative, non-proteobacteria
Produce no O2 during photosynthesis
Green non-sulfur bacteria use organic compounds such as carbohydrates or acids as reactant in place of
H2S (hydrogen sulfur)

Question 22

Chlamydiae [Clamydia]

Answer 22

Other gram negative bacteria
Cocci
Do not contain peptidoglycan in their cell wall
Transmitted from human to human
Obligate intracellular parasites
Medical impact: Neonatal blindness [Chlamydia trachomatis], Pneumonia, STIs

Question 23

Spirochetes

Answer 23

Other gram negative proteobacteria
Coiled morphology -> Axial filaments, which leads to corkscrew like motility
Found in human oral cavity
A number of important pathogens:
Treponema -> Treponema pallidum: Syphilis
Borrelia -> Borrelia burgdorferi: Lyme disease

Question 24

Clostridium

Answer 24

Gram positive, Firmicutes [Low G + C]

Obligate anaerobes
Rod shape with endospores that play an important role in pathogenicity and food spoilage
Diseases associated with clostridia:
C. tetani: Tetanus – an infection characterized by muscle spasms; contact with contaminated objects
C. perfringens: Normal component in decaying vegetation, microbiota of animals and insects, marine sediments
Food borne disease + Gas gangrene – open wounds
C. botulinum: Botulisum – muscle weakness (Floppy baby syndrome)
C. difficile: C. Difficile associated diarreah

Question 25

Streptococcus

Answer 25

Gram positive, Firmicutes [Low G + C]
Spherical, usually in chains
Produce extracellular substances that contribute to pathogenesis: Enzymes that destroy phagocytic
cells, that digest the hosts connective tissues, that digest the fibrin in blood clots
Responsible for more illnesses and variety of diseases than any other group
1) Beta-hemolytic—produce hemolysin that lyse blood cells and form clear zone in blood agar plate
– S. pyogenes (Also called Group A strep) -> Causative agent of: scarlet fever, sore throat, rheumatic fever
– S. agalactiae (Group B strep): Postpartum infections and neonatal sepsis
2) Alpha-hemolytic— On blood agar plate colonies surrounded by a greenish hue, due to partial destruction of the red blood cells
– S. pneumoniae: Pneumococcal pneumonia
– S. mutans: Dental decay

Question 26

Staphylococcus

Answer 26

Gram positive, Firmicutes [Low G + C]
Cocci, grape like clusters
Grows in nasal passages and on skin as part of our normal microbiota
S. aureus- infection of wounds in surgical procedure
- Produces many toxins that contribute to pathogenecity: produces toxins that can cause toxic shock
syndrome, can develop drug resistance quickly

Question 27

Streptomyces

Answer 27

Gram positive, Actinobacteria [High G + C]
Filamentous growth
Aerobic, commonly found in soil
Spores form at the end of aerial filaments
Produce most of our common antibiotics:
- Antibacterial: Chloramphenicol, Neomycin, Streptomycin, Tetracycline, Fosfomycin, Daptomycin
- Antifungal: Polyene antimycotic
- Antiparasitic: Ivermectin

Question 28

Mycobacterium

Answer 28

Aerobic
Non-spore forming rods
Distinctive cell wall -> Acid fast stain (mycolic acid)
Drug resistance
Pathogenicity
Diseases: M. tuberculosis, M. leprae

Question 29

Trypanosomes

Answer 29

Protozoan, Euglenozoa [Trypanosome gambiense]
African sleeping disease -> Transmitted by tsetse fly; Threatens mainly populations of remote rural areas with limited health services
Fever, headache, enlarged lymph nodes, joint pains and itching. Latter stages parasite crosses into the central nervous system causing the meningo-encephalitic
Without treatment it’s usually fatal!
[Trypanosome cruzi]
Chagas disease
Transmitted by kissing bug -> Bites on the face; insect feces contains the trypanosome which then infects the bite

Question 30

Giardia

Answer 30

Protozoan, Diplomonadida [Giardia lamblia]
Most common cause of water borne disease giardiasis; cysts excreted in feces survives in environment