Bacterial diversity Flashcards
(27 cards)
what are the best studied phyl
Domain bacteria
- Cyanobacteria: oxygenic phototrophs
- Gram positivev: Firmicutes, tenericutes and actinobacteria
- Gram negative: proteobacteria
- Gram neg: Spirchetes, Acidobacteria, Bacteroidetes and chlorobi
- PVC superperphylum: planctomycetes, verrucomicrobia, chlamydiae (unqiue bacteria not very well understood_
describe deep-branching thermophiles
- not all extremophiles are archaea
- the deep-branching bacteria include extremophiles that have similar physiology to archaea and found in same habitats
- generally exhibit fast growth rate and high rates of mutation
examples extreame deep-branching thermophiles
- Aquificase and thermotogae = most extreame bacteria hyperthermophiles (70-95), mostly lithotrophs, inhabit hydrothermal vent zones (volcanic areas on ocena floor)
- genomes show extensive horizontal transfer of archaeal genes (ether-linked membrane lipids)
- aquifex pyrophilus = flagellated rod; energy from H2 oxidation
- thermocrinis ruber = filamentous mats in hydrothermal vents
- thermotoga maritima = uses anaerobic respiration; respires on sulfure
examples of moderate deep branching thermophiles
- phylum: deinococcus thermus
- as a group they are moderate (70-75), all heterotrophs
- ex: deinococcus radiodurans bacterium
- extreamly resistant to ionizing radiation and desiccation
- each cell has multiple copies of the chromosome, tighly wound together
- multiple DNA repair mechansims/enzymes (good biotech research candidate)
- Thick cell wall and S-layer (peptideglycan contains unusual amino acids so it can be resistant to extreme conditions)
- heterotroph
what are phylum cyanobacteria
- The only oxygenic photoautotrophic prokaryotes
- contain chlorophyll a and b (abs light in blue & red spectrum) which gives cells a green appearance (bc of autofluorescence)
- water is the electron donor (photolysis of water)
- contain phycocyanin accessory proteins (abs light ->chlorophyl)
All of O2 gas on earths atmosphere come from cyanobacteria and plant chloroplasts evolved from ancient cyanobacterium
- conduct photosynthesis in thylakoids (phototrophs), fix CO2 in carboxysomes (autotrophs), maintain buoyancy using gas vesicles, many are diazotrophs: fix N2 to ammonia in heterocyst cells
Many also conduct photolithoautrotrophy
- anaerobic photosynthesis using reduced sulfur (not water) as e- donor
Have various cell shapes, morphologies and cell organisation
- single celled, filamentous, colonial
what are thylakoids
- extensions of cytoplasmic membrane containing photosynthetic pigmets
- extend into cytoplasm to extend surface area where photosynthesis can occur
diversity of lifestyles amoung cyanobacteria
- free living in fresh and marine water soils
- mutualistic associations with corals, fungi, plants, protists
- few species can sporulate
*note some produce highly toxic potent toxins
what are the 3 distinct phylogenetic branches of gram positive bacteria
- phylum firmicutes: Low GC species
- phylum actinobacteria: High GC species
- Tenericutes (aka mollicutes): no cell wall
- whats Bacillales
- firmicutes
gram pos
- well studies and one of first bacterial genera to be studied
- large, rod shaped
ex: B. subtillis = a model system for gram positives
B. anthracis = found in soil, causative agent of anthrax
- vegetative cells develop inert endospores in times of starvation and stress - released spores germinate in favourable conditions
*spore develops in mother cell
what is bacillus thuringiensis
- firmicutes
- used as bio contorl agent (most successful)
- spores (formed in mother cell) is found with crystaline inclusion
- this is sold as biocontrol agent (BT toxin)
- spores are applies as an insecticide agonist gypsy moth caterpillar
- sporulating cell produces a crystal that contains an insectal protein known as delta toxin
- toxin activated in the alkaline environemnt and forms holes in the stomach lining/intestinal lining
describe the clostridium genusof firmicutes
- habitat: soil and can contaminate foods
- rod shaped
- endospores swell forming a drumstick
- endospores are resistant to killing by desiccation, leat, low levels of radiation
- contains important animal and human pathogens
ex: C. botulinum: toxin causes flaccid paralysis muscles relax and fail to contract (botox is a modified version),
C. tetani: causes muscles to contract and fail to realx
C. difficile: cause of chronic ‘C.diff’ gastrointestinal disease, has endospores so antibiotics will kill cells but endospores remain and activate when antibiotic gone
C. tetani
describe lactice acid bacteria
- no spore forming firmicutes
- bacillales and clostridales as well as other gram-positive orders, include many non-spore forming rods and cocci
*lactic acid bacteria (fermenting bacteria), aerotolerant bacteria and can grow in present of oxygen even tho dont use it
^used in fermentation industry: lactococcus, lactobacillus and leuconostoc
compare the non spore forming firmicutes - staph and strep species
Staphylococcus
- faculative anaerobes
- cocci in clusters
- staph. aureus (MRSA, methicilin-resistant S. aureus serous disease, flesh eating disease)
Streptococcus
- Aerotolerant
- cocci in chains
- step. pneumoniae (effects lungs), strep. pyogenes (produces many toxins, mainly causes skin infections)
what are antinomycetes
- gram positive
- an oder in the phylum actinobacteria include non-sporulating Mycobacterium species
- spore forming actinomyces form complex multicellular filaments superficially resembling the branched fuzzy form of fungi
- streptomyces: major group of soil dwelling organisms, obligate anerobes, major antibiotic producers, spread by spores and fragmentation of mycelia into smaller cells
what are the 5 major classes of proteobacteria
*gram neg
- alpha, beta, gamma, delta and epsilon
describe the phylum proteobacteria
- gram neg
- all share common structure: triple layered gram neg cell envelope
*outer membrane, thin peptidoglycan, periplasm
- have diverse metabolism: diversity arises through minor “add-ons” of biochemical molecules
^fermentation, aerobic and anerobic respiration
- include: heterotrophs, photoheterotrophs, oligotrophs, lithotrophs, methylotrophs (can use methane as carbon source)
- have diverse lifestyles: free living, in symbioses, some are pathogens
what are alphaproteobacteria
- Endosymbionts
- Nitrogen fixers and plant roots
ex: Rhizobium and Sinorhizobium (two genus) - As isolated bacteria, they are generally rod-shaped with aerobic metabolism.
- Within the cells of plant roots the bacteria lose their cell wall (defence mech) and become rounded bacteroids, specialized for nitrogen fixation.
- The host plant cells provide the bacteroids with nutrients, as well as leghemoglobin, a protein that maintains anaerobiosis within infected cells.
what can cause tumors in plants
- agrobacterium (type of alphaproteobacteria)
- able to transfer DNA via bacterial Ti plasmid into plant cells is exploited to create transgenic plants
describe beta- proteobacteria
- heterotrophic, require nutrient rich environment
- includes many animal pathogens - Neisseria gonorrhoeae, pseudomonas aeruginosa
Neisseria meningitidis growing in colonies on a chocolate agar plate. (credit: Centers for Disease Control and Prevention)
what is gammaproteobacteria
- include enteric bacteria (collectively called the enterobacteriaceae colonize the colon (large intestine of animals)
- shared traits: G-ve rods; motile via flagella; tolerant to bile salts, faculative anerobes and fermentation
- include many species pathogenic to humans and animals
ex: e.coli, salmonella, shigela, proteus, campylobacter, helicobacter pylori
what is Bdellovibrio
bacteria parasites of other bacteria
Deltaproteobacterium - Gram-negative aerobe bacterium
- Parasitize proteobacterial cells
- The “attack cell” is a small, comma-shaped rod with a single flagellum.
- It penetrates the periplasm, when in there goes into this long organism and occupies the majority of cell, eats cytoplasm, host cell loses its shape and becomes a protective incubator for the predator.
- This stage is called the bdelloplast.
- It eventually bursts, releasing the newly formed attack cells.
Vampirococcus: extracellular parasite of chromatium sp (phototrophic sulfur bacteria/lithoautotroph) *atached to surface feeds from outside
Daptobacter: penetrates and grows in the cytoplasm of G- bacteria
