Microbiological Methods VIII-B-1
Microbiological Methods of the Member Companies of the
Corn Refiners Association
Accepted 03-30-93
Revised 02-01-07
MESOPHILIC ANAEROBIC BACTERIA
(POUR PLATE METHOD)
PRINCIPLE
Viable anaerobic bacteria are quantitated by the fractional gram pour plate
technique under an anaerobic atmosphere. Caution must be exercised when
applying the method since isolates may be pathogenic.
SCOPE
The method is applicable to starches, syrups, sugars and most co-products of the
corn wet milling industry.
SPECIAL APPARATUS
Anaerobic jars, BBL GasPak or equivalent, equipped with GasPak hydrogen and
CO2 generator envelopes with an anaerobic indicator.
MEDIA AND REAGENTS
1. Anaerobic Agar (ANA). Prepare according to manufacturer's directions
(Note 1).
2. Butterfield's Phosphate Diluent
Stock Solution: Dissolve 34 g of potassium dihydrogen phosphate
(KH2PO4) in 500 mL of purified water, adjust to pH 7.2 with about 175 mL
of 1N NaOH solution and dilute to 1 L volume. Store under refrigeration.
Diluent: Dilute 1.25 mL of stock solution to 1 L volume with purified
water. Prepare dilution blanks using this solution.
3. Dilution Blanks. Fill dilution bottles to appropriate volume with
Butterfield's Phosphate Diluent (Note 2).
