EDUCATION“ The purpose of education is

to replace an empty mind with an open one.”

Bacteriology

• 1st observed by Leeuwenhoek – 1676 with single lens microscope

Definition - Bacteria• Single-celled microorganisms with a variety of shapes

(spheres, rods, spirals)• a.k.a. Prokaryotes b/c they do not contain a nucleus

(membrane bound organelle)– Genetic material contained in a single circular chromosome

in the cytoplasm of the cell (nucleoid)

Prokaryotic• Prokaryotic

– Fewer organelle & smaller than Euk.

– Cell wall• +/- capsule

– Cell/ plasma membrane– Nucleoid– Cytoplasm– Ribosomes– +/-: pili, plasmids, flagellum– Few have endospore

• Eukaryotic– Cell / plasma membrane– Nucleus– Nucleolus– Cytoplasm– Mitochondria– Golgi apparatus– Endoplasmic reticulum– Ribosomes– Vacuoles– Lysosomes

Bacteriology• Grow in kinds of environments, extremes• Without bacteria life as we know it would cease to

exist!

Bacteriology

• Bacterial cells outnumber the other cells in our bodies by 10:1!

• Majority harmless or beneficial– Digestive tracts of people and animals (ex:

ruminants) Few cause infectious disease–Most common – respiratory diseases

Bacteriology – Morphology

• Wide variety– Spherical –

cocci/coccus– Rod –

bacilli/bacillus– Single cells, pairs,

chains, clusters– Elongated to form

filaments

Bacteria

Bacteriology – Cellular Structure• Cell membrane – Barrier to hold nutrients, proteins and other

components of cytoplasm within cell– No membrane-bound organelles – few intracellular

structures• No nucleus, mitochondria, chloroplasts, golgi apparatus

and endoplasmic reticulum

• Genetic material – single circular chromosome – In nucleoid in cytoplasm

Not membrane bound

Smaller than Eukaryotic

Barrier againstphagocytosis

Hairlike protein extensionsAttach/communicate withOther cells

DNA outside chromosomeReplicate independentlyPass info via pilus

Mobility

FEW BACTERIA HAVE ABILITY TO PRODUCE ENDOSPORESPersists in variable environment

Bacteriology

• Treat infections with antibiotics• Also used for agricultural processes• Industrial processes–Waste treatment– Cheese and yogurt production–Manufacture of antibiotics and other chemicals

Bacteriology

Bacteriology – Extracellular Structures

• Cell wall – around cell membrane– Essential to survival of many bacteria• Penicillin kills by inhibiting a step in synthesis of cell

wall– 2 types• Gram positive – thick cell wall with many layers• Gram negative – thin cell wall• Based on reaction to Gram stain• Differences in antibiotic susceptibility

Gram Staining• The bacterial kingdom is subdivided into main

categories by a process called Gram Staining (named after Hans Christian Gram, a Danish bacteriologist). The process is a stain that illustrates the composition of the cell wall.

The gram stain consists of these steps.

• Crystal violet - stains both gram negative and positive bacteriaGram's iodine - fixes the stain in gram positive bacteriaEthanol or acetone - washes the stain from gram negative bacteriaSafranin - counterstain, will re-stain gram negative bacteria while not interfering with the previous stain in gram positive bacteria

Gram stain Procedure

Staphlylococcus sp.Streptococcus sp.

Salmonella sp.Proteus sp.

Bacteriology – Extracellular Structures

• Glycocalyx (a network of polysaccharides)– Surrounds the cell wall• Varies in structural complexity

– Disorganized extra-cellular polymer = slime layer– Highly structured = capsule

– Protect from engulfment by macrophages– Act as antigens – Cell recognition– Allows attachment to inert surfaces (teeth, rocks,

etc)

Bacteriology – Endospores• Highly resistant, dormant structures• Consist of central core of cytoplasm containing DNA and

ribosomes surrounded by cortex layer• Protected by impermeable and rigid coat• Certain genera of Gram-positive bacteria

– Bacillus– Clostridium

Bacteriology – Endospores• No detectable metabolism• Survive extreme physical and chemical

stresses– UV light– Gamma radiation– Detergents/disinfectants– Heat– Pressure– Drying

Bacteriology – Endospores

• Survive millions of years• Survive exposures to vacuum/radiation in

space• Can cause disease– Inhalation of Bacillus anthracis endospores– Contamination of deep puncture wounds with

Clostridium tetani endospores => tetanus

Anthrax

Tetanus

Bacteriology – Pathogens• Definition – bacteria or other agent that forms

a parasitic association with other organisms• Major cause of human and animal death and

disease– Examples: tetanus, food-borne illness

(Salmonella, Campylobacteria), leprosy, Tuberculosis (TB)

• Important in agriculture– Johne’s disease, mastitis, salmonella, anthrax

Bacteriology – Pathogens

• Each species has characteristic spectrum of interactions with hosts– Ex: Staph/Strep => skin infections, pneumonia,

meningitis, sepsis• Can also be part of normal flora w/o causing

any disease

Bacteriology – Pathogens

• Some organisms always cause disease – Ex :Rickettsia – gram (-) obligate intracellular

parasites– Ehrlichia– Rickettsia rickettsii (RMSF)

– Chlamydia – obligate intracellular parasite• Pneumonia• Urinary tract infections

Bacteriology – Pathogens

• Opportunistic– Primarily in immune suppressed hosts

Bacteriology – Pathogens

• Treatment– Antibiotics • Bacteriocidal• Bacteriostatic• Many types – each class inhibits a process in pathogen

that is different from host

Bacteriology – Pathogens

• Prevention by using antiseptic measures– Sterilizing skin prior to needle puncture– Proper care of indwelling catheters – Sterilization of surgical and dental instruments

• Disinfectants– Kill bacteria/other pathogens on surfaces – Ex: bleach; Roccal, chlorhexidine

Bacteriology – Growth and Reproduction

• Grow to fixed size• Asexual reproduction – binary fission• Can be rapid under optimal conditions– Double every 9.8 minutes

• 2 identical clone daughter cells formed• Can also form more complex reproductive

structures that facilitate dispersal

Bacteriology – Growth and Reproduction

• Cultured with solid or liquid media– Solid – agar plates – used to isolate pure cultures

of a bacterial strain– Liquid • Measurement of growth• Large volumes needed

– Selective media• Specific nutrients added or deficient or antibiotics

added• Used to ID specific organisms

Bacterial Reproduction

• http://www.sciencebuddies.org/science-fair-projects/project_ideas/MicroBio_Interpreting_Plates.shtml