conjugation plasmid
gene to transfer plasmid
High frequency recombination
HFR
F+
bacteria has plasmid
F-
bacteria doesnt have plasmid
Fermentation
is an energy producing biochemical reaction in which organic molecules serve as both electron acceptors and electron donors
ONPG
colorless substance but O-nitrophenol produce yellow color
negative: colorless
positive: yellow
e. coli (+)
alcaligenes faecalis (-)
Triple sugar iron agar test (TSI)
-Aim: To identify and distinguish the enterobacteriaceae from other G -ve organisms.
-What to detect?- presence of sugar fermantation, gas production, H2S production
-Expected reaction:
yellow butt + red slant- glucose fermentation,
yellow butt + yellow s
The IMViC test
Aim: To identify enteric bacteria; proteins
INDOLE PRODUCTIOn
Bacteria produces enzyme tryptophanase to hydrolyse an amino acid called tryptophan to a metabolic product indole, reacts with the kovac's reagent to give color change is postivie reaction
e. coli (+)
e. aerogenes (-)
Methyl red test
It's a pH indicator; color change is positive test
e. coli (+)
e. aerogenes (-)
Voges-proskauer test:
This test detects acetoin; + test: Red color development within 15 min of addition of barritt's reagent
e. aerogenes (+)
e. coli (-)
Citrate utilization test
causes an alkaline product formation which increases the pH of medium and cause the color change.
+ citrate test: color change from green to blue; e. aerogenes
- citrate test: no color change (remains green); e. coli
Gelatin Hydrolysis
certain bacteria produces an enzyme gelatinase which liquifies gelatin
+ gelatin test: liquefied medium.
- gelatin test: no liquefaction
Bacteria:
Enterobacter aerogenes: (+), slow liquefaction
Proteus vulgaris: (+), fast liquefaction
E.coli: Gelatinase (
Catalase activity
Some bacteria produces an enzyme called catalase to protect themselves from free radicals like hydrogen peroxide, superoxide etc.
-If bubbles are present, test is positive
-Bacteria:
Staph. aureus: (+)
Enterococcus faecalis( - )
Coagulase test
(+) bacteria form a fibrin clot around themselves to protect against the host's defenses+ve test: clotting present
-ve test: no clotting in 4 hrs
-Bacteria:
Staph. aureus- (+),
-Staph. epidermis (-)
DNase test
-DNase is an enzyme produced by bacteria that degrades host DNA and increase the pathogenicity
-A zone of clearing around the colony indicate +ve DNase activity.
-Bacteria:
Staph. aureus- (+),
-Staph. epidermis (-)
Oxidase test
Oxidase enzymes like cytochrome oxidase plays important role in electron transport chain for energy production.
-Reduced cytochrome -oxidase oxidized cytochrome
-Oxidase cytochrome + reagent blue
-E. coli- (-)
Pseudomonas aerugenosa- (+)
Urease activity
On utilization of urea by bacteria, there is production of ammonia which increases the pH resulting in color change from orange red to deep pink or purplish red (+ve reaction).
-Urea -urease CO2 + H20 + NH3
-Bacteria: Klebsiella pneumonia, Proteus vulgari
Lysine and Ornithine decarboxylase activity
Decarboxylation is the removal of a carboxyl group from an organic molecule.
-Bacteria that are able to produce the enzymes lysine decarboxylase and ornithine decarboxylase can decarboxylate lysine and ornithine and uses the amines as precursors for the s
Phenylalanine Deamination
Phenylalanine deaminase catalyzes the removal of amino group from phenylalanine.
-Phenyl adanine -PA deaminase phenyl pyruvic acid + NH4+ + H20
Fe Cl3 + phenyl pyruvic green color
-p. vulgaris (+)
-e.coli (-)
Nitrate reduction
Nitrate reductase enzyme produced by certain bacteria reduces nitrate to nitrite
-NO3- (nitoates) + 2H + 2e- --nitrate reductase NO2 (nitrites) + H20 (go down) -sulpharalic acid N,N-dimethyl 1-napthylamin red dye
Might not get red because of other enzymes
obligate aerobe
need oxygen to grow; grow on surface of test tube
faculative anerobe
grow in presense or absense of oxygen; grow throughout test tube
obligate anerobe
grows only in absense of oxygen; oxygen is harmful to these bacteria; grow at bottom of test tube
areotolerant
cannot us oxygen but are not harmed by it; will grow throughout the test tube
microareophils
needs small amount of oxygen but are inhibited by atmospheric pressures
commercially designed broth
way to culture anaerobic bacteria; meat medium, thioglocoliate broth
wright's tube
way to culture anaerobic bacteria; nutrient agar slant; uses pyrugallcol and NaOH
Brewers anaerobic petrie dish
way to culture anaerobic bacteria; contains thioglocoliate; sulfhydryl groups reduce oxygen
gas pak anaerobic system
way to culture anaerobic bacteria; contains palladium catalysts in chamber lid to catalyze formation of water
oxyrase
way to culture anaerobic bacteria; oxrase is used to reduce oxygen
areobic chamber
chamber with no air; methyl blue goes from blue to colorless in anerobic conditiions
Kirby Bauer
Muller-Hinton plates; swab bacteria; stamp antibacterial circles on to see if the bacteria is resistant or not
antibiograms
bacterial antibiotic profile
zone of inhibition
if bacteria are not resistance and cant grow around the antibiotic it makes a clear zone
MIC (minimum inhibition concetration)
minimum amount of antibiotic that will inhibit growth
E tests
tests MIC; uses antibiotic strips of different concentrations inorder to test
indirect counting
counting colonies; below 25, not good results; above 250, TNTC (too numerous to count)
CFU
colony forming units
spectrophotometeric
light gets absorbed or reflected when bacteria grow in a test tube
growth chart
chart of how bacteria grow in a batch
lag phase
no growth, no divisions
log phase
growth
stationary phase
no more food; growth evens out; stress resistant
decline
death