Microbiology Lab Practical 1

• it contains more than one lens
• can be monocular (one eyepiece) or binocular (2 eyepieces)

• condenser
• iris diaphragm
• objective lens
• ocular lens
• mechanical stage
• course and fine adjustments

light goes from the light source in the base through a condenser which focuses the light beams

controls the amount of light that passes through the specimen

• magnifies the object
• 10x, 40x or 100x

further magnifies 10x

• allows you to move the slide in order to see different specimens on it
• use the x/y axis adjustment

• help you to focus the image
• only use fine at 1000x

• resolution power- the closest that two objects can be and still be seen as seperate objects under the microscope
• compound light microscope can resolve objects seperated by 0.2uM or more

ocular x objective

:)

• cocci- circle
• bacilli- rods
• coccobacilli- short rods
• vibrio- comma
• spirochete- corkscrew
• spirilla- wavy

• have a thick peptidoglycan cell wall
• stain purple (crystal violet primary stain)
• Examples: staphlyococcus, streptococcus, enterococcus, clostridium (botulism and tetanus)

• thin peptidoglycan cell wall
• has an outer membrane with LPS that can be an endotoxin- can enter circulatory system and cause a toxic reaction
• takes up counter stain (safranin- red)
• examples: e.coli, salmonella, psudomonas, helicobacter

• fixation
• crystal violet
• iodine treatment
• decolorization
• counter stain safranin

• used to visualize the endospores of some bacterial cells
• uses malachite green for endospores (green) and safranin for vegetative (red) cells. 
• primary stain- malachite green
• counter stain- safranin

• physical property of certain bacteria and their resistance to acid dyes
• bacteria that hold onto the first dye are considered acid fast bc they resist the acid wash
• very slow growers (mycolic acid layer)
• acid fast- pink (carbolfuchsin, primary stain)
• not acid fast- blue (methylene blue, counter stain)

the overall shape of the colony

the side view of the colony, is it raised?

the shoreline, the most outer parts

• punctiform: small circles
• circular: round
• filamentous: lots of lines coming out
• irregular: no distinct shape
• rhizoid: like filamentous but not as many lines
• spindle: rod looking

• flat: not raised at all
• raised: slightly raised with no curve
• convex: looks like a hill, raises to the top
• pulvinate: taller form of convex
• umbonate: an irregular hill. looks like an egg yolk atop the rest of the egg

• entire: smooth circular edge
• undulate: spikey rough edge
• lobate: crown looking edge
• erose: very spikey fuzzy edge, like undulate but more and closer spikes
• filamentous: many lines
• curled: many layers- looks like a tree stump

• circular
• umbonate
• entire (some look undulate)

• circular
• opaque
• convex
• entire

• rhizoid or filamentous
• flat
• erose

edge looks lobate when swarming

• Circular
• umbonate
• entire, some look undulate
• looks like e.coli but red

• circular (sometimes irregular)
• yellow/brown
• umbonate
• undulate

• punctiform
• convex
• entire
• translucent

• white- e.coli
• yellow- staph aureus

s. pyogenes

b. subtilis

p. vulgaris

• can grow in an environment with O2
• an obligate aerobe MUST have O2

• can grow with out O2
• obligate anaerobes will die when O2 present

• complex nutritional requirements
• they are picky

facultative organism

obligate

• enriched differential medium that determines oxygen requirements of microorganisms
• produces a range of oxygen levels in the medium
• indicated by a redox sensitive dye

a pellicle

facultative anaerobe

• facultative anaerobe
• prefers more oxygen over no oxygen

• microaerophile
• need some O2 but is poisoned by a lot of it
• will be found just a bit below the surface in the thioglycolate tube

• aerobe/ facultative aerobe
• will form a pellicle- layer of growth at the broth air interface right at the top

anaerobe

found in thioglycolate broth and allows it to provide both anaerobic and aerobic conditions based on spots in the tube

we use it to counteract the angle of refraction

• the iris diaphragm controls the amount of light hittting the sample
• you may need to close this to better see your sample because it will increase the contrast to see your sample better, but if closed too far itll be too dark

bcc using the 10x will give you a larger field of view to find your specimen. then you can move up in power to see it closer once youve found it. you can also use the course adjustment at 10x objective to focus where you cant higher

it makes things appear blurry and can damage the microscope

• acid fast- pink (carbolfuschin)
• spores- green (malachite green)
• vegetative cells- red (safranin)
• gram positive- purple (crystal violet)
• non acid fast- blue (methylene blue)
• gram negative- red/pink (safranin)

pink acid fast bacilli; scattered

• blue (non acid fast) clustered cocci
• gram positive (would stain purple)

diagnosing tuberculosis or leprosy which are both acid fast bacteria

• mycobacterium tuberculosis
• mycobacterium leprae

• in the acid fast stain it helps that thick mycolic acid layer open up to accept the dye
• spores are DNA with a thick resistant protein coat and the steam helps that coat open up to accept the dye

• b. cereus- chained bacilli, showed up pink bc vegetative
• b. subtilis- scattered bacilli, also pink and vegetative

more spores=under more/longer distress

they can be used to make enzymes and antibiotics.

• b. cereus can be in food, it produces toxins and can cause diarrhea and vomiting (it is gram positive tho). you wouldnt want to ingest the spores bc they can become vegetattive in your body
• tetanus spores can live in the soil for 30 years