Bacteria Flashcards
Gram staining
Staining with Crystal Violet Fixing with Grams iodine Washing with alcohol/acetone Positive- purple Negative - pink (counterstained with Basic Fuchsin)
Size
0,5-2 micrometers
Positive vs negative
Positive - peptidoglycan like cables, thicker walls, more robust
Negative - glycan makes single layer, additional polysaccharide membrane, resistant to toxic chemicals
Cell wall
Peptidoglycan
2D mesh-like polysaccharide chains
Cross linked by short peptides
Characteristics
Poles Nucleoid Unique ribosomes and polysaccharides Membranes and central metabolic pathways similar to eukaryotes Rapid reproduction
Reproduction
Cylinder elongation Nucleoid replication MreB ParA separates chromosomes FtsZ
MreB
Arranges material for new cell wall in a helix
Gene B of murein region
Murein = peptidoglycan
Related to actin
FtsZ
Filamentation, temperature sensitive
Forms z-ring
Related to tubulin
Shapes -8
Rods Cocci (spheres) Filaments Vibrios (curved rods) Spirilla (helical filaments) Spirochaetes (wrapped around own flagella) Actin bacteria (branched) Mycelium (fungus-like)
Outside structures
Flagella
Fimbriae
Pili
Capsule
Flagella
Rotates like propeller
Polar or peritrichious
Fimbriae
Attaching to surfaces
Pili
Sex or type 4
Retractable
Capsule
Protection against desiccation
Attachment
Made from polysaccharides
Przetrwalniki
Endospores
After asymmetrical division
Mother cell+ forespore
Anthrax, tetanus
Types of reaction to oxygen
Aerobic
Facultatively anaerobic
Aerotolerant
Strictly anaerobic
Natural life cycle
Swimming form(chemotaxis) Surface associated motility (swarming or twitching) Microcolony Biofilm Quorum sensing
Cultivation
Agar (colonies)
Broth (rotary shaker, homogeneous dispersion)
Anaerobic jar (air replaced by CO2, N2, H2)
Classification by nutrition
Chemoheterotrophs
Chemoautotrophs
Photoheterotrophs
Photoautotrophs
Autotrophs
Source of carbon = CO2
Reducing power = H2, H2S, NH3, NO2-, Fe2+
Autotrophs - carbon fixing cycles -4
Calvin-Benson cycle (plants, Cyanobacteria, purple bacteria)
Reverse TCA
Hydroxypropionate pathway
Acetyl-COA p.
Heterotrophs
Source of carbon = absorbing organic molecules
Can’t phagocitate
Large polymers need to be broken down before absorption
Chemo(…)trophs
Oxidise organic chemicals to get energy
Photo(…)trophs
Use light energy
Bacteriochlorophyll
Outdated method of classification
Bergey’s manual of systematic bacteriology
Classification by 16S sequencing -4
Proteobacteria
Firmicutes
Actinibacteria
Smaller g- groups (actinobacteria)
Proteobacteria
Most of g- bacteria
Purple photosynthetic bacteria
Subdivided into alpha, beta, gamma, epsilon
Firmicutes
G+
Low GC content in DNA
Actinobacteria
G+
High GC content in DNA
Phylogenetic stuff -3
Most of smaller groups is g-, so g- are the ancestors
Lowest branches of tree are hyperthermophilic
Chlorophyll-based photosynthesis widely distributed = core adaptation developed early on
Important bacteria
E. coli
S. aureus
C. Difficile
Escherichia coli -8
Used as a host for gene manipulation Forms 1% of gut bacteria G- Rod Facultatively anaerobic Chemoheterotrophic Motile by peritrichious flagella Some strains cause urinary tract infections
Staphylococcus aureus -9
G+ Cocci Facultatively anaerobic Firmicutes Found in nasal membranes Causes infection of wounds Food poisoning Secondary pneumonia MRSA - methicillin resistant S. Aureus
Clostridium difficile -6
G+ Rod Strictly anaerobic Firmicute Endospore forming Can dominate gut flora after antibiotic therapy causing antibiotic-associated colitis
