Ubiquity Of Microorganisms 1u3t6h

Ubiquity of Microorganisms Yasmine Al-shboul M265 General Microbiology lab

Microorganisms are ubiquitous • Bacterial species characteristics: • • • • •

Colony morphology. Cell morphology. Biochemical properties. Antibiotic sensitivity. ** Knowledge of these characteristics allows correct & easy identification of bacteria from mixed cultures

• Principle of colony formation: • 1 cell  1 colony

•

Growth characteristics of bacterial colonies (on Agar):

• •

Size (mm-cm) Pin point, small, medium, large

• •

Elevation (side view): Flat, raised, convex, umbonate, crateriform.

• •

Edge or margin: Entire, lobate, curled, undulate, filamentous (filiform), erose.

• Whole colony shape (Form): • Filamentous, irregular, circular, rhizoid. • Texture: • Moist, mucoid, dry (rough) • • • •

Pigmentation: Color of colony may change on different agar types. Appearance: (Opaque or translucent), (shiny or dull).

• Odor (listed if distinctive) • Sweet, putrefied, fruity.

Colony morphology

pseudomonas aeruginosa

• Slant and deep media

Motility test.

Growth characteristics in broth:

• Aseptic Technique: • A procedure used in microbiology laboratories that protects the person, others, the work area, and the culture from contamination.

Suggested procedures to use to achieve Aseptic Technique: • Covering & sterilizing of culture media during preparation. • Sterilization of bench tops before and after use. • Sterilization of inoculation loop. • Do not talk while cultures are open. • Never leave a tube or a plate open any longer than necessary. • Flame the lips of the tube before and after inoculation with the loop. • Work quickly on all transfers. • Never place the cap or plug on the work surface or let it touch anything except the flamed lip and culture tube. • Wash hands before and after work.

Techniques for isolation of pure cultures • 1- Streak plate method: • - The most widely used method for obtaining isolated colonies from a mixed culture. • - It's a qualitative method that depends on dilution. • - 1 cell  1 colony. • - Procedure.

• streaking method

• • •

2- Spread-plate Technique. - Not commonly used - Procedure.

–

•

• • • • •

Sub-culturing: Transfer of microorganisms from one media to another by one of the transfer instruments. Transfer instruments Inoculating loops and needles: Made of Ni-chrome or Platinum. Flaming = incineration. Flaming begins at handle  tip, this will prevent formation of aerosols.

• • •

Pipettes: Sterile & prepackaged. Disposable (in a biohazard box).

• • •

Swabs: Sterile & prepackaged. Disposable (in a biohazard box).

• • •

3- Pour-plate Technique: - Not commonly used - Procedure.