BIOL 133 Lab 2 Exam Questions and
Answers with Verified Solutions | Latest
Updated 2026
How to identify a species of 1. find and isolate a pure strain of the
bacteria disease
causing bacteria by swabbing and
streaking an
agar plate
2. isolate a pure culture from the mixed
plate
3. analyze the culture by incolulating a
variety of
media
4. determine by metabolic characteristics,
drug or
chemical sensitivity, interaction with
anti-serum or
viruses, and oxygen requirments
Enterobacteriaceae a family of bacteria that can grow with or
without
oxygen
part of normal mammalian flora of
intestines
some are pathogenic
selective media prevent the growth of some types of
bacteria or
microorganisms
, differential media allow many types of MOs to grow but,
based on
the MO, may appear different in the culture
Sorbitol and inositol fermentation liquid culture media
tubes used to test the use of different carbs
the break down of sorbitol and inositol =
acid
(change from red to yellow)
the production of gas is trapped in the
upside
down Durham tube in the media (gas
bubble
production)
+ result - cloudy/yellow (acid +), bubble in
Durham
tube (gas +)
- result - cloudy/red (acid -), no bubble in
Durham
tube (gas -)
MacConkey agar plates Used to:
determine Lactose utilization
inhibit Gram + growth
pH indication
Gram (-) = colony growth
utilization of lactose = acid production = pH
indicator turns colony from white to
pink/red
+ result - red/pink colonies
- result - colourless/white colonies
Answers with Verified Solutions | Latest
Updated 2026
How to identify a species of 1. find and isolate a pure strain of the
bacteria disease
causing bacteria by swabbing and
streaking an
agar plate
2. isolate a pure culture from the mixed
plate
3. analyze the culture by incolulating a
variety of
media
4. determine by metabolic characteristics,
drug or
chemical sensitivity, interaction with
anti-serum or
viruses, and oxygen requirments
Enterobacteriaceae a family of bacteria that can grow with or
without
oxygen
part of normal mammalian flora of
intestines
some are pathogenic
selective media prevent the growth of some types of
bacteria or
microorganisms
, differential media allow many types of MOs to grow but,
based on
the MO, may appear different in the culture
Sorbitol and inositol fermentation liquid culture media
tubes used to test the use of different carbs
the break down of sorbitol and inositol =
acid
(change from red to yellow)
the production of gas is trapped in the
upside
down Durham tube in the media (gas
bubble
production)
+ result - cloudy/yellow (acid +), bubble in
Durham
tube (gas +)
- result - cloudy/red (acid -), no bubble in
Durham
tube (gas -)
MacConkey agar plates Used to:
determine Lactose utilization
inhibit Gram + growth
pH indication
Gram (-) = colony growth
utilization of lactose = acid production = pH
indicator turns colony from white to
pink/red
+ result - red/pink colonies
- result - colourless/white colonies
