Exercise 5-12 Micro Lab: Starch Hydrolysis
Hydrolysis reactions
reactions that use water to split complex molecules
Hydrolytic enzymes
intracellular enzymes detected by a Urease Test that are required to catalyze hydrolysis reactions
intracellular
when the enzyme catalyzes its reaction inside the cell
extracellular (exoenzymes)
enzymes secreted from the organism to catalyze reactions outside the cell
gelatinase
an exoenzyme that liquefies the solid medium
Nutrient geletain detects what?
gelatinase
What 4 media are plated media that identify extracellular enzymes capable of diffusing into the medium and producing a distinguishable halo of clearing around the bacterial growth?
1. DNase Agar
2. Milk Agar
3. Tributyrin Agar
4. Starch Agar
starch
a polysaccharide made up of a-D-glucose subunits.
Starch exists in what two forms?
1. linear (amylose)
2. branched (amylopectin)
usually as a mixture with the branched configuration being predominant
Whats the deal with starch and the bacterial cell membrane?
Starch is too large to pass through it, so it has to split into smaller fragments or individual glucose molecules in order to be of any metabolic value
a-amylase
oligo-1, 6-glucosidase
these enzymes are able to hydrolyze starch by breaking the glycosidic linkages between sugar subunits.
starch agar
a simple plated medium of beef extract, soluble starch, and agar
What is used to detect the presence or absence of starch in the vicinity around the bacterial growth?
iodine
Iodine reacts with starch and produces what color?
a blue or dark brown color
starch agar was originally designed for cultivating _____
Neisseria
a clearing around the bacterial growth indicates what?
amalayse present