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IDENTIFIKASI BAKTERI

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... Azotobacter can be identified from soil samples incubated aerobically on such media A. KARAKTERISTIK FENOTIF Metabolic differences Biochemical tests ... – PowerPoint PPT presentation

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Title: IDENTIFIKASI BAKTERI


1
IDENTIFIKASI BAKTERI
  • OLEH
  • SUDRAJAT
  • FMIPA UNMUL
  • 2009

2
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Colony morphology
  • Colonies can exhibit macroscopic differences
  • e.g., Colonies of streptococci generally form
    fairly small colonies
  • e.g., Colonies of Serratia marcescens produce a
    pigment and are often red when incubated at 22oC
  • e.g., Colonies of Pseudomonas aeruginosa often
    produce a soluble greenish pigment

Pseudomonas aeruginosa
3
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Culture characteristics
  • Selective and differential media can aid in the
    identification of microbes
  • Selective media favors the growth of certain
    types of microbes by inhibiting the growth of
    others
  • Differential media contains a substance that
    certain bacteria change in a recognizable way

4
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Culture characteristics
  • MacConkey agar is both selective and
    differential
  • Bile salts and dyes inhibit all but certain
    gram-negative rods
  • Selective
  • Acid produced by bacteria able to ferment lactose
    will turn a pH indicator red and form red
    colonies
  • Differential

5
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Culture characteristics
  • Blood agar can be used to detect bacteria
    producing hemolysins
  • e.g., Harmless Streptococcus species residing in
    the throat often cause alpha-hemolysis
  • Greenish clearing around colonies
  • e.g., Strep throat-causing Streptococcus
    pyogenes causes beta-hemolysis
  • Clear zone around colonies

6
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Culture characteristics
  • Media lacking nitrogen can be used to detect
    nitrogen-fixing bacteria
  • e.g., Azotobacter can be identified from soil
    samples incubated aerobically on such media

7
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Biochemical tests
  • Generally necessary for more conclusive
    identification
  • Most rely on pH indicator or color change when a
    compound is degraded

8
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Biochemical tests
  • Sugar fermentation
  • e.g., Lactose, sucrose, glucose, etc.
  • Fermentation results in acid production
  • pH indicator changes color
  • Pink ? yellow
  • Inverted tube (Durham tube) collects any gas
    produced

9
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Biochemical tests
  • Urease detection
  • Enzyme degrading urea
  • Urea ? CO2 NH3
  • pH indicator turns bright pink in alkaline
    conditions
  • Helicobacter pylori can be detected using a
    breath test

10
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Biochemical tests
  • Urease detection
  • Helicobacter pylori can be detected using a
    breath test
  • Causative agent of most stomach ulcers
  • Culturing not necessary
  • Patient drinks solution containing 14C-labeled
    urea
  • 14C in expired are indicates presence of urease

11
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Biochemical tests
  • Catalase
  • Commonly occurring enzyme
  • Possessed by most bacteria growing in the
    presence of oxygen
  • Absent in lactic acid bacteria
  • e.g., Streptococcus
  • Beta-hemolytic catalase-negative bacteria from a
    throat culture may be Streptococcus pyogenes

12
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Biochemical tests
  • Catalase
  • Simple assay
  • H2O2 ? H2O O2
  • O2 bubbles are visible

13
A. KARAKTERISTIK FENOTIF
14
A. KARAKTERISTIK FENOTIF
  • Organisms are identified using a dichotomous key
  • Multiple biochemical and other tests are
    typically required
  • Multiple tests are generally run concurrently
  • Avoids waiting for incubation time for each test

15
A. KARAKTERISTIK FENOTIF
  • Metabolic differences
  • Biochemical tests
  • Commercial modifications of traditional
    biochemical tests
  • e.g., APITM system, EnterotubeTM

16
Metabolic Phenotypic Exam
  • cultural approaches
  • required for positive diagnosis of infection
  • isolation and ID of pathogen
  • accuracy, reliability, and speed
  • specimen collection is important
  • commonly used for positive identification of most
    prokaryotes
  • methods used include
  • culture characteristics
  • biochemical reactions process

17
Metabolic Phenotypic Exam
  • culture characteristics
  • organisms grown in a pure culture are easier to
    identify due to the high number of organisms
    obtained

E. coli
18
Metabolic Phenotypic Exam
  • culture characteristics
  • use of selective or differential media can
    provide additional information
  • selective media inhibits the growth of organisms
    other than the one being sought
  • differential media contains substances that
    particular bacteria change in a recognizable way

19
Metabolic Phenotypic Exam
When identifying a suspected organism, a series
of differential media is inoculated. After
incubation, each medium is observed to see if
specific end products of metabolism are present.
This can be done by adding indicators to the
medium that react specifically with the end
product being tested, giving some form of visible
reaction such as a color change. The results of
these tests on the suspected microorganism are
then compared to known results for that organism
to confirm its identification.
20
Metabolic Phenotypic Exam
Some bacteria will produce the enzyme catalase.
Catalase will break down hydrogen peroxide
releasing oxygen, which is indicated by the
bubbles that have formed.
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