microbiology - w1: ubiquity of microorganisms & colony morphology

microorganisms

organisms that are too small to be seen without the aid of magnification

- includes viruses/prions (not necessarily alive)

- helminths (worms); (adults not microscopic, infective stages ARE microscopic)

microorganisms exclusion

only places where microorganisms are not found are places where we intentionally exclude them

ex) microorganisms not usually found in blood/cerebrospinal fluid

ubiquity of microorganisms

refers to the concept that microorganisms are everywhere

- contaminates surfaces of objects we use

- in the air, food, water, etc.

growth medium

laboratory preparation that contains nutrients that are appropriate for growing microorganisms

- mixture of nutrients determines range of microbes that can grow

Culture Media (medium, singular)

Solution of nutrients required for the growth of bacteria

Agar

A carbohydrate derived from seaweed used to solidify a liquid

Tryptic Soy Agar (TSA)

A rich solid medium containing a digest of casein (the principal milk protein) & soy products

- an all-purpose medium that supports the growth of many diverse organisms

Tryptic Soy Broth (TSB)

A rich liquid medium containing a digest of casein and soy products

- is a general-purpose medium that supports the growth of organisms that are not exacting in their food requirements

Colony

A visible population of microorganisms originating from a single parent cell & growing on a solid medium

Colony Morphology

Distinctive shapes & colors that colonies take on when on an agar media; affected by:

- species of bacteria

- media

- temperature

- age of growth

Whole Shape of Colony

Varies from round to irregular to filamentous & rhizoid (root-like)

Size of Colony

Can vary from large colonies to tiny colonies less than 1 mm = punctiform (pin-point); measure with millimeter rule

Edge/Margin of Colony

Magnified edge shape (use a dissecting microscope to see the margin edge well)

Chromogenesis

- Color of colonies, pigmentation (white, buff, red, purple, etc.)

- Some pigments are water-soluble; others not

- If you take a large inoculum & place it in a tube of water or saline, do you see color?

- Do you see pigment if the organism is growing in a broth medium?

- Does incubation temperature affect the color?

- Does the entire colony have the color, or is it more like a bull's eye?

Opacity of Colony

Is the colony?:

- transparent (clear)

- opaque (not transparent or clear)

- translucent (almost clear, but distorted vision-like looking through frosted glass)

- iridescent (changing colors in reflected light)

Elevation of Colony

How much does this colony rise above the agar (turn the plane on end to determine height)?

Surface of Colony

Smooth, glistening, rough, dull (opposite of glistening), rugose (wrinkled)

Consistency or Texture

Butyrous (buttery), viscid (sticks to loop, hard to get off), brittle/friable (dry, breaks apart), mucoid (sticky, mucus-like)