Equipment and Materials

Chapter 3

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Chapter 3
Last Updated
2026-06-01
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Conventional Plate Count Method

Equipment and Materials

  1. The work bench should be leveled, clean and with ample surface. The laboratory should be free of dust and drafts. The microbial density of air in working area, measured in fallout pour plates taken during plating, should not exceed 15 colonies/ plate during 15 min exposure.
  2. Storage space, free of dust and insects and adequate for protection of equipment and supplies
  3. Petri dishes, glass, or plastic (at least 15 × 90 mm)
  4. Pipets with pipet aids (no mouth pipetting) or pipettors, 1, 5, and 10 ml, graduated in 0.1 ml units
  5. Dilution bottles, 6 oz (160 ml), borosilicate-resistant glass, with rubber stoppers or plastic screw caps
  6. Pipet and petri dish containers, adequate for protection
  7. Circulating water bath, for tempering agar, thermostatically controlled to 45 ± 1°C
  8. Incubator, 35 ± 1°C; milk, 32 ± 1°C
  9. Colony counter, dark-field, Quebec, or equivalent, with suitable light source and grid plate
  10. Tally register
  11. Dilution blanks, 90 ± 1 ml Butterfield's phosphate-buffered dilution water (R11); milk, 99 ± 2 ml
  12. Plate count agar (standard methods) (M124)
  13. Refrigerator, to cool and maintain samples at 0-5°C; milk, 0-4.4°C
  14. Freezer, to maintain frozen samples from -15 to -20°C
  15. Thermometers with appropriate range; accuracy checked with a thermometer certified by the National Institute of Standards and Technology (NIST)

Spiral Plate Method

Equipment and Materials

  1. Spiral plater
  2. Spiral colony counter with special grid for relating deposited sample volumes to specific portions of petri dishes
  3. Vacuum trap for disposal of liquids (2-4 liter vacuum bottle to act as vacuum reservoir and vacuum source of 50-60 cm Hg)
  4. Disposable micro beakers, 5 ml
  5. Petri dishes, plastic or glass, 150 × 15 mm or 100 × 15 mm
  6. Plate count agar (standard methods) (M124)
  7. Calculator (optional), inexpensive electronic hand calculator is recommended
  8. Polyethylene bags for storing prepared plates
  9. Commercial sodium hypochlorite solution, about 5% NaOCl (bleach)
  10. Sterile dilution water
  11. Syringe, with Luer tip for obstructions in stylus; capacity not critical
  12. Work area, storage space, refrigerator, thermometers, tally, incubator, as described for Conventional Plate Count Method, above