CHAPTER 3. Content purification of cultures morphological and pureculture studies biochemical tests.
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Transcript of CHAPTER 3. Content purification of cultures morphological and pureculture studies biochemical tests.
Purification of culturesThe only way to purified culture are by
getting a pure culture.Have a control procedure in collecting
specimen, preparing media, microbiological tecniques, staining and reagents and equipment used.
Collecting specimenSterile procedure using a correct media for
transportation and stock.Main source for bacteria should be microbial
food. Which are??The transport media used to preserve and
ensure the viability of bacteria during the transportation period
Besides also provide a particular temperature for the viability of bacteria
Crucial for cerebrospinal fluid, blood culture and fecal specimens, etc.
Preparation of mediaThe media should be packed well to prevent
from leakage and breaks, protected from moisture and sunlight and excessive heat
The expiry date should be noted and the instruction of storage should be followed
The mix bacterial colonies should be sub cultured until the culture are purified
the bacterial colony characteristic should only derive from a single colony
Biochemical testsCatalase testOxidase testCoagulase testSugar fermentation testMRVP testIndole testCitrate testMotility testH2S test
Catalase testProduce bubble just
after attaching the bacteria to the reagent
To differentiate staphylococci and streptococci
Oxidase testHave 2 methods:Filter paper/Sterile swabTo help identify Vibrio, Neisseria, Pasteurella
and Pseudomonas sp.Oxidase enzymes oxydize phenylenediamine.Deep purple colour on reagent paper
Coagulase testTo identify S.aureusThe enzyme
coagulase clots plasma
Tube : fibrin clotSlide: clumping of
bacterial cells
Sugar fermentation testGlucose testMaltose testSucrose testLactose testSome will appear
with gas production
Voges-Proskauer testTo differentiate
enterobacteriaOrganism ferments
glucose with acetoin production. Acetoin is oxidised to diacetyl which reacts with creatine
Brick red colour develop slowly
Methyl Red testTo differentiate
enterobacteriaOrg. ferment
glucose, producing sufficient acidity in buffered medium to give a colour change of indicator
Brick red medium
Indole testUsing Kovac reagent.To differentiate Gram
negative rods, especially E.coli
Tryptophan is broken down wt the release of indole which reacts wt dimethylaminobenzaldehyde
Reddening of strip or medium
Citrate testTo differentiate
enterobacteria from other bacteria
Org uses citrate as its only source of carbon, producing an alkaline reaction wt colour change indicator
Blue and turbid medium