Bacteria classification Flashcards
What are the general characteristics used to classify bacteria
- traditional: size, shape, arrangement, gram reaction, need for O2
- ability to metabolize sugar
- metabolic end products
What are bacteria supplemented by
Comparison of 100 to 300 characteristics
Nucleic acid sequence of ribosomal RNA
Antigenic composition
Based on O2 requirement
What are aerobes
grow in ambient air and small amounts of CO2
What obligate aerobes
have absolute requirement for O2, cannot ferment
What are anaerobes
usually can not grow in the presence of oxygen. the methods that exclude: closed vessels, reducing agents, anaerobic jar and glove box
What are obligate anaerobe
are killed by normal atmospheric concentration of oxygen
What are facilitative anaerobe
oxygen is present, respire aerobically otherwise capable of shifting to fermentation or anaerobic respiration
What are microaerophilic
need oxygen but not high concentration
What are aerotolerant
does not require oxygen and are not poisoned by it
What types of test administered for bacteria
sugar and catalase
What sugars are used for identifying bacteria
sucrose, glucose, mannitol and lactose
what bacteria uses the sugar test
E.coli and Staphloccocus
What is catalase test
a test where enzymes of a bacteria decompose H2O2
What is citrate utilization test
some bacteria utilize citrate as the sole source of carbon and alkalinize the medium.
What is the medium of the citrate test
Simmon’s citrate medium that has bromothymol blue
What is H2S production test
is produced by the breakdown of sulphur containing amino acids and thisulphate
What happens to the medium of the H2S production
Medium rich in iron show a black color due to the formation of ferrous sulphide
What bacterias are tested with H2S
ex. salmonella and proteus
What bacteria are tested with citrate
Klebsiella and E.coli
What is the Indole test
some organisms convert tryptophan to free indole
What is the reaction that happens in indole test
tryptophan is hydrolysed by tryptophanase
What bacteria is tested in the indole test
E. coli
What is the urease test
Urea by the enzyme urease. it uses the christensen urease medium that is made of 2% urea and phenol
What is the indicator of the urease test
red indicator. ammonia release raises pH intense pink-red color
What bacteria are tested in the urease test
ex. Klebsiella and E.coli
What is the deaminase test
deamination produces phenylpyruvic acid which is defected in a colormetric test. after growth add ferric cholride reagent like for green color.
What is the Voges Prskauer test
chemical test for acetone
What bacteria are tested with the Voges Proskauer
it separate Klebsiella and enterobacter from Escherichia
What is nitrate reduction test
nitrate as alternate electron acceptor reduced to NO2. broth with nitrate and agter incubation detects nitrate with anpthylamine, sulfanilic acid
What is the gelatin liquefaction test
many protease hydrolyze gelatin and destroy the gel
What is coagulase test
enzyme cause clotting of blood plasma. mix dense liquid suspension of bacteria with plasma, incubate and look for sign of lot in few minutes
What bacteria are tested in coagulase test
ex. S. aureus and S. epidermidis
