Classification of Bacteria

Taxonomy The science of classification

Haeckel’s 3 Kingdoms Plant Animal Protista

Carl Woese’s 3 Domains Based on rRNA nucleotide sequences Why use this as a basis for classification?

Organisms in the 3 Domains Eukarya - kingdoms: plantae, animalia, fungi, protists Archaea - prokaryotes Bacteria - prokaryotes

2 Types of Prokaryotic Cells Eubacteria –cell walls contain peptidoglycan –different nucleotide sequences in rRNA –different membrane lipids Archaebacteria –no peptidoglycan –rRNA –lipids –live in extreme environments ex. Thermoacidophiles Extreme halophiles Methanogens

Comparison of Archaea, Bacteria & Eukarya

Naming organisms (nomenclature) Binomial system uses 2 names Genusspecies ex. Bacillussubtilis ex. Clostridiumtetani ex. Staphylococcusaureus Is tubercle bacillus the scientific name of an organism or a common name?

Taxonomic Categories Order ends in –ales in fungi, plantae & bacteria Family ends in- aceae in fungi, plantae & bacteria

Species of bacteria - “population of cells with similar characteristics” Strain of bacteria - “group of cells derived from a single cell” ex. Staphylococcus aureus 13578

Classification vs. Identification Techniques Bergey’s Manual of Determinative Bacteriology uses: microscopic appearance biochemical reactions growth requirements serology phage typing Classification or identification??

Biochemical Tests

Serology Slide Agglutination Test

Phage Typing

Bergey’s Manual of Systematic Bacteriology establishes phylogenetic relationships by: amino acid sequencing protein analysis rRNA sequencing – ribotyping –Why is rRNA rather than other types of RNA used? Chapter 10 nucleic acid hybridization Classification or identification??

DNA Hybridization

Identification vs. Classification

Spirochetes Axial filaments for motility Examples: Treponema pallidum - syphillis Borrelia burgdorferi - Lyme disease Leptospira interrogans - leptospirosis

Axial Filaments Movement of spirochetes Bundles of fibrils that arise at the end of the cell beneath the outer sheath & spiral around the cell Ex. Treponema pallidum Structure Filament Hook Basal body

Campylobacter jejuni microaerophilic motile vibrio Gram negative animals esp poultry & cattle 42 o C most commonly identified bacterial cause of diarrhea in world (CDC) –unpasteurized milk –food

Pseudomonas aeruginosa Gram negative aerobic rod “bacillus of blue-green pus” –pyocyanin pigment fermented grape smell normal flora –skin & intestine unusual carbon sources antibiotic resistant infections –wound, ear, urinary, respiratory, burns

Gram negative aerobic cocci Neisseria gonorrhoeae in pus Neisseria meningitidis Branhamella catarrhalis

Enterobacteriales Non-pathogens Escherichia Klebsiella Proteus Serratia Etc. Family- enterobacteriaceae Describe the microscopic appearance of these organisms.

Enterobacteriaceae cont’d Pathogens Salmonella (typhi) –typhoid fever Shigella (dysenteriae) –bacillary dysentery Yersinia (pestis) –bubonic plague Can you see why the family, enterobacteriaceae, has been referred to as the Colon-typhoid-dysentery group? Can you differentiate the pathogens from the non- pathogens microscopically? All members of Enterobacteriaceae are facultative anaerobes. Meaning?

Vibrionales Vibrionaceae Vibrio cholerae Shape? Facultatively anaerobic

Hemophilus influenzae Aerobic Gram negative rod Normal flora in intestine and respiratory tract Most common cause of meningitis in children –Hib vaccine Also causes otitis media, pneumonia, epiglottitis Why is the name of this organism misleading? What can you learn from the name?

Bacteroidaceae - Bacteroides fragilis Gram negative anaerobic rods Found in the human intestine & mouth –95% of the bacteria in a stool specimen & 20% of the weight! –One billion per gram of feces! Most common anaerobe isolated from infections –appendicitis, peritonitis, complicate abdominal surgery

Rickettsia & Chlamydia Gram negative obligate intracellular parasites Rickettsia transmitted to humans by insects & ticks Ex. Rickettsia rickettsii - Rocky Mountain spotted fever

Chlamydia Not transmitted by insects Chlamydia trachomatis Causes: 1.Trachoma - world’s leading infectious cause of blindness Middle East, North Africa, India 2.Non-gonococcal urethritis common std in U.S.

Chlamydia psittaci causes: 1. Psittacosis (“parrot fever”) 2. Ornithosis Chlamydia pneumoniae - pneumonia

Mycoplasmas No cell wall –pleomorphic –penicillin sensitive or resistant? Smallest free-living organisms Microscopic fried-egg colonies Ex. Mycoplasma pneumoniae

Gram Positive Cocci StaphylococcusStreptococcus Micrococcus luteus

Staphylococcus aureus Gram positive cocci, clusters Yellow pigment Causes –common food poisoning –surgical wound infections resistance –toxic shock syndrome

Streptococcus pyogenes Gram positive cocci in chains Diseases –pharyngitis (sore throat) –scarlet fever * –erysipelas * * look for a description of this disease

Endospore-Forming Gram Positive Rods Bacillales - Bacillus –aerobes or facultative anaerobes –common in soil –ex. Bacillus anthracis, Bacillus subtilis Clostridiales - Clostridium –obligate anaerobes –found in soil –diseases tetanus (Clostridium tetani), botulism (C. botulinum), gas gangrene (C. perfringens)

Spore-Forming Organisms Bacillus cereus - spore stain Clostridium tetani - Gram stain

Corynebacterium Characteristics of Corynebacterium sp.: pleomorphic Gram positive rod metachromatic granules unusual arrangements –palisades –Chinese letters C.diphtheriae causes diphtheria

Mycobacteria Characteristics of Mycobacterium sp. Gram positive small rods acid-fast –mycolic acid complexed with peptidoglycan (waxy) diseases: –tuberculosis –leprosy (M. leprae) Acid-fast stain of sputum showing Mycobacterium tuberculosis

Streptomycetes Characteristics of Streptomyces: mold-like bacteria –branching, spores produce geosmin –soil smell several species produce antibiotics –ex. streptomycin

The End!