Bacterial Genetics Flashcards
Science concerned with hereditary and variation
Genetics
Most common bacterial reproduction and important in bacterial growth cycle
Asexual Mode
Exchange of genes between 2 DNA molecules to form combination of genes in a chromose
Gene recombination
Change in the base sequence of cell/organism which may occur naturally or through induction by agents
Mutations
Bacteral reproduction where bacteria are not differentiated to somatic or gametic cells
Sexual Mode
2 functional/mating types
Donor (male)
Recipient (female)
Involves a unidirectional transfer of a portion of DNA from donor or recipient
Sexual Mode
Gene transfer =
Genetic recombination
Genetic recombination =
Changes
Changes =
Variations
Metods of genetic transfer
Conjugation
Transduction
Transformation
Protoplast Fusion
Transfer of genetic information via cell-to-cell contact
Conjugation
Extra chromosal, independently replicating DNA found in bacteria and yeasts
Plasmids
Plasmid that can exist with or without being integrated into the host’s chromosome
Episome
Have genes for sex pili (transfer gene)
Conjugative plasmids
Fertility factor - genes for cell attachment, genes for transfer
F factor
Contains extra chromosomal F factor (donor)
F+
No F factor (recipient)
F-
High frequency of recombination
F factor integrated into bacterial chromosme
Donor
Hfr
Transfer of bacterial genes by viruses (most common mechanism)
Transduction
Two kinds of transduction
Generalized
Specialized / Restricted
Occurs during the lytic cycle of virulent and temperate viruses
Host DNA derived from any portion of the host genome becomes a part of the DNA of the virion in place of the virus’ genome
Generalized Transduction
Occurs only in some temperate viruses
Involves transfer of specific region of the host chromosome into the virus replacing some of the viral genes
Specialized / Restricted Transduction
Uptake by a cell of a naked DNA molecule or fragment from the medium and the incorporation of this molecule into the recipient chromosome
Contact with competent cell (able to take up DNA)
Transformation
Used in microorganisms with NO known conjugation system
Enzymes are used to digest cell wall to produce protoplasts
Protoplast Fusion
Industrially important aerobic organisms that convert ethanol into acetic acid (vinegar)
Acetobacter
Gluconobacter
Obligate intracellular parasite transmitted to humans by insect and tick bites
Responsible for a number of diseases known as the spotted fever group
Rickettsia sp.
Causes endemic murine typhus
R. typhi
Rickettsia-like bacteria that live obligately within white blood cells
Trabsmitted by ticks to humans and cause ehrlichiosis
Ehrlichia sp.
Freshwater microorganism
Caulobacter
Hyphomicrobium
Agriculturally important bacteria
Rhizobium
Bradyrhizobium
Agrobacterium
Small nonmotile coccobacilli
Obligate parasites and cause brucellosis
Brucella sp.
Genera of nitrifying bacteria that are of great importance to the environment and to agriculture
Nitrobacter
Nitrosomonas
Most common infectious bacterial genus in the world
Live only inside the cells of their hosts
Wolbachia
Found mainly in freshwater
Spirillum
Pseudomonas-like, aerobic
Burkholderia
Best known species of Burkholderia and has an extraordinary nutritional spectrum and is capable of degrading more than 100 different organic molecules. These bacteria may actually grow in disinfectant solutions.
Burkholderia cepacia
Aerobic
Neisseria
Causative agent of gonorrhoea
Neisseria gonorrhoeae
Agent of meningococcal meningitis
N. meningitidis
Aerobic rods or cocci with polar flagella
Pseudomonas
Pseudomonas aeruginosa
Nitrogen fixing bacteria
Free living in soil
Azotobacter
Azomonas
Strictly aerobic coccobacilli
Moraxella
Implicated in conjunctivitis
Moraxella lacunata
Aerobic and typically forms pairs
Occurs naturally in soil and water
Acinetobacter
Increasing concern to the medical community because of rapidity with which it becomes resistant to antibiotics
Acinetobacter baumanii
Originally isolated during a search for the cause of an outbreak of pneumonia now known as legionellosis
Legionella
Require mammalian host to reproduce
Most commonly transmitted by contaminated milk
Coxiella
Causes Q fever
Coxiella burnetii
Facultative anaerobic gram-negative rods
Found mostly in aquatic habitats
Vibrio
Causative agent of cholera
Vibrio cholerae
Causes a less serious form of gastroenteritis
Transmitted to humans mostly by raw or undercooked shellfish
V. parahaemolyticus
Facultative anaerobic, gram negative rods that are if motile, peritrichously flagellated
Enterobacteriales
e.g. escherichia, salmonella, shigella etc.
Very important genus of pathogenic bacteria
Haemophilus
Cause of meningitis in young children and is a frequent cause of earaches
Causes epiglottis
Haemophilus influenzae
The best studied sulfur reducing genus
Found in aerobic sediments and in the intestinal tracts of humans and animals
Desulfovibrio
Microaerophilic vibrios
Each cell has one polar flagellum
Campylobacter
Causes spontaneous abortion in domestic animals
Campylobacter fetus
A leading cause of outbreak of foodborne intestinal disease
Campylobacter jejuni
Microaerophilic curved roots with multiple flagella
Helicobacter
Identified as the most common cause of peptic ulcers in humans and a cause of stomach cancer
Helicobacter pylori
Pathogenic bacteria that may cause trachoma (one of the most common cause of blindness)
Chlamydia
Chlamydia trachomatis
Live in human intestinal tract in numbers approaching 1 billion per gram of feces; Nonmotile
Bacteroides
Long, slender, gram negative rods with pointed rather than blunt ends
Found most often in the gingival crevice of the gums and may be responsible for some dental abscesses
Fusobacterium
A spirochetes
Treponema
Cause of syphilis
Treponema pallidum
Causes relapsing fever and Lyme disease, serious diseases that are usually transmitted by ticks or lice
Borrelia
Causes leptospirosis
A disease usually spread to humans by water contaminated
Leptospira
Exceptionally resistant to radiation, even more so than endospores
Deinococcus radiodurans
A bacterium is unusually heat stable
It was isolated from a hot spring in yellowstone national park
Thermus aquaticus
Obligate anaerobes
Rods
Endospore formers
Clostridium
Causes tetanus
Clostridium tetani
Causes botulism
Clostridium botulinum
Causes gas gangrene and foodborne diarrhea
Clostridium perfringens
An inhabitant of the intestinal tract that may cause a serious diarrhea
Clostridium difficile
Rods
Endospore formers
Common in soil and only a few are pathogenic to humans
Several species produce antibiotics
Bacillus
Causes anthrax
Bacillus anthracis
A common bacterium in the enivronment and occasionally is identified as a cause of food poisoning, especially in strachy foods such as rice
Bacillus ceres
Occus in grapelike clusters
Facultative anaerobes
Staphylococcus
Can cause skin infections and food poisoning
Staphylococcus aureus
Industrially important lactic-acid producing bacteria
Aerotolerant
Located in the vagina, intestinal tract, and oral cavity
Lactobacillus
Spherical, gram positive bacteria that typicalky appear in chains
There are pathogenic and non pathogenic strains
Streptococcus
A beta-hemolytic streptococcus
Causes scarlet fever, pharyngitis, erysipelas, impetigo, and rheumatic fever
Streptococcus pyogenes
Adapted to area of the body that are rich in nutrients but low in oxygen, such as gastrointestinal tract, vagina, and oral cavity
Have high resistance to most antibiotics
Enterococcus
Responsible for much of the infections of surgical wounds and the urinary tract
Enterococcus faecalis
Enterococcus faecium
The cause of a common form of mild pneumonia
Mycoplasma pneumoniae
Can contaminate food, especially dairy products
Capable of growth at refigeration temperatures
Poses threat of stillbirth or serious damage to the fetus if it infects pregnant women
Listeria monocytogenes
Aerobic
Non-endospore forming rods
Mycobacterium
Causes tuberculosis
Mycobacterium tuberculosis
Causes leprosy
Mycobacterium leprae
Tend to be pleomorphic and their morphology often varies with the age of the cells
Corynebacterium
Causative agent of diphtheria
Corynebacterium diphtheriae
Produces propionic acid
Some species are important in the fermentation of Swiss chees
Propionibacterium
Bacteria that are commonly found on human skin and are implicated as the primary bacterial cause of acne
Propionibacterium acnes
The best know of the actinomyces and is one of the bacteria most commonly isolated from soil
Strict aerobes
Valuable because the produce most of our commercialantibiotics
Streptomyces
Facultative anaerobes that are found in the mouth and throat of humans and animals
Actinomyces
Causes actinomycosis, a tissue destroying disease usually affecting the head, neck, or lungs
Actinomyces israelii
Morphologicalky resembles Actinomyces; however, these bacteria are aerobic; they are often acid-fast; common in soil
Nocardia
Occasionally cause a chronic, difficult-to-treat pulmonary infection
Causative agents of mycetoma, a localized destructive infection of the feet and hands
Nocardia asteroides