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Briggs agar
416
Handbook of Culture Mediafor Food Microbiology, J.E.L. Corry et al. (Eds.) 9 2003 Elsevier Science B.V. All rights reserved
Briggs agar This monograph has been reviewed by members of the IUMS-ICFMH Working Party on Culture Media and given 'Proposed' status. Description and history Briggs tomato juice agar (Briggs, 1953) was developed primarily for the cultivation of lactobacilli from milk and dairy products and has since been successfully used for strains from other sources (Cox and Briggs, 1954; Lerche and Reuter, 1960; Reuter, 1964). It may be used for the non-selective enumeration of the whole group of lactic acid bacteria and has better productivity for some strains of Lactobacillus delbrueckii ssp. bulgaricus, Streptococcus thermophilus and Lactococcus lactis ssp. lactis than MRS agar.
Composition (grams) Tryptic digest of casein Peptic digest of meat Yeast extract Glucose Starch, soluble Sorbitan monooleate (Tween 80) Sodium chloride Agar
8.0 8.0 6.0 20.0 0.5 1.0 5.0 20.0
Distilled or deionized water 600.0, 800.0 or 900.0 (depending on tomato juice used, a,b orc) additionally: a) Tomato juice dilution
One part of the commercial product without salt and preserving agents is diluted with two parts water, boiled and filtered. 400 ml of this dilution is added to 600 ml basal agar.
b) Fresh tomato juice
Filter the juice of freshly pulped tomatoes to remove seeds and coarse particles. Autoclave and add 200 ml to 800 ml of the basal agar.
417 c) Tomato extract dilution Mix 40 g tomato extract (triple), 5.75 g Na2HPO 4, 0.8 g KH2PO 4 in 500 ml water, filter and autoclave at 121~ for 15 min. Add 100 ml to 900 ml basal agar. The remainder may be stored for future use.
Preparation Suspend the ingredients in the appropriate amount of water and add the diluted tomato juice or tomato extract dilution. Heat to boiling to dissolve completely. Adjust pH to 6.8 with 10% NaOH. Sterilize in the autoclave for 15 min at 121~ Cool to 50~ and distribute into sterile Petri dishes. Avoid overheating this medium which hydrolyses the agar, resulting in a soft medium. N.B. The tomato juice must be free of Cu contamination.
Physical properties Appearance pH
Medium to dark amber, slightly opalescent, may have a slight precipitate. 6.8 +0.2
Shelf life Tomato extract dilution Ready to use medium
4-6 weeks at 4 + 2~ 14 days at 4 + 2~ D
Inoculation method for samples Surface spreading over whole plate or modified Miles-Misra.
Incubation method This depends on the particular habitat of the organisms to be cultivated. Dairy strains should be incubated at 30~ for 2 days followed by 1 day at 22~ intestinal or yoghurt strains for 2 days at either 37 or 42~ All incubations should be performed under anaerobic or microaerobic (6% 02: 10% CO 2 in N2) conditions.
Reading of results and interpretation Briggs agar is an elective medium that gives good colony counts and a similar colony size and appearance for all lactic acid bacteria. Other microorganisms may be distinguished by pigments and extraordinary colonial morphology (micrococci, Gram negative species, yeasts). Confirmation tests e.g. Gram stain, catalase reaction, are necessary to distinguish mixed microflora. A selective medium for lactobacilli or lactic acid bacteria should be used in parallel where very mixed microflora are present.
418
Quality assessment (i) Productivity Test strains
Lactobacillus delbrueckii ssp. bulgaricus NCIMB 50050
Streptococcus thermophilus NCIMB 50083 Lactococcus lactis ssp. lactis NCIMB 50058 Inoculation method
Modified Miles-Misra, spiral plating or streaking/ ecometry.
Criteria
Recovery on Briggs agar should be within 1 log~0 of recovery on MRS agar.
(ii) Characteristic appearance of colonies Small greyish-white colonies, 1-3 m m diameter, flat or raised, smooth, rough or intermediate. Non-lactic acid bacteria e.g. yeasts and Gram-negative species, may be distinguished by colony size and appearance after further incubation at room temperature.
References Briggs, M.J. (1953) An improved medium for lactobacilli. J. Dairy Res. 20, 36--40. Cox, C.P. and Briggs, M.J. (1954) Experiments on growth media for lactobacilli. J. Appl. Bacteriol. 17, 18-26. Lerche, M. and Reuter, G. (1960) Beitrag zur Methodik der Isolierung und Differenzierung von aerob wachsenden Laktobazillen. Zbl. Bakteriol. I. Orig. 179, 354-370. Reuter, G. (1964) Vergleichsuntersuchungen an 90 thermophilen Lactobazillen Stammen verschiedener Herkunft. Zbl. Bakteriol. I. Orig. 193,454-466.
Handbook of Culture Mediafor Food Microbiology, J.E.L. Corry et al. (Eds.) 9 2003 Elsevier Science B.V. All rights reserved
Briggs agar This monograph has been reviewed by members of the IUMS-ICFMH Working Party on Culture Media and given 'Proposed' status. Description and history Briggs tomato juice agar (Briggs, 1953) was developed primarily for the cultivation of lactobacilli from milk and dairy products and has since been successfully used for strains from other sources (Cox and Briggs, 1954; Lerche and Reuter, 1960; Reuter, 1964). It may be used for the non-selective enumeration of the whole group of lactic acid bacteria and has better productivity for some strains of Lactobacillus delbrueckii ssp. bulgaricus, Streptococcus thermophilus and Lactococcus lactis ssp. lactis than MRS agar.
Composition (grams) Tryptic digest of casein Peptic digest of meat Yeast extract Glucose Starch, soluble Sorbitan monooleate (Tween 80) Sodium chloride Agar
8.0 8.0 6.0 20.0 0.5 1.0 5.0 20.0
Distilled or deionized water 600.0, 800.0 or 900.0 (depending on tomato juice used, a,b orc) additionally: a) Tomato juice dilution
One part of the commercial product without salt and preserving agents is diluted with two parts water, boiled and filtered. 400 ml of this dilution is added to 600 ml basal agar.
b) Fresh tomato juice
Filter the juice of freshly pulped tomatoes to remove seeds and coarse particles. Autoclave and add 200 ml to 800 ml of the basal agar.
417 c) Tomato extract dilution Mix 40 g tomato extract (triple), 5.75 g Na2HPO 4, 0.8 g KH2PO 4 in 500 ml water, filter and autoclave at 121~ for 15 min. Add 100 ml to 900 ml basal agar. The remainder may be stored for future use.
Preparation Suspend the ingredients in the appropriate amount of water and add the diluted tomato juice or tomato extract dilution. Heat to boiling to dissolve completely. Adjust pH to 6.8 with 10% NaOH. Sterilize in the autoclave for 15 min at 121~ Cool to 50~ and distribute into sterile Petri dishes. Avoid overheating this medium which hydrolyses the agar, resulting in a soft medium. N.B. The tomato juice must be free of Cu contamination.
Physical properties Appearance pH
Medium to dark amber, slightly opalescent, may have a slight precipitate. 6.8 +0.2
Shelf life Tomato extract dilution Ready to use medium
4-6 weeks at 4 + 2~ 14 days at 4 + 2~ D
Inoculation method for samples Surface spreading over whole plate or modified Miles-Misra.
Incubation method This depends on the particular habitat of the organisms to be cultivated. Dairy strains should be incubated at 30~ for 2 days followed by 1 day at 22~ intestinal or yoghurt strains for 2 days at either 37 or 42~ All incubations should be performed under anaerobic or microaerobic (6% 02: 10% CO 2 in N2) conditions.
Reading of results and interpretation Briggs agar is an elective medium that gives good colony counts and a similar colony size and appearance for all lactic acid bacteria. Other microorganisms may be distinguished by pigments and extraordinary colonial morphology (micrococci, Gram negative species, yeasts). Confirmation tests e.g. Gram stain, catalase reaction, are necessary to distinguish mixed microflora. A selective medium for lactobacilli or lactic acid bacteria should be used in parallel where very mixed microflora are present.
418
Quality assessment (i) Productivity Test strains
Lactobacillus delbrueckii ssp. bulgaricus NCIMB 50050
Streptococcus thermophilus NCIMB 50083 Lactococcus lactis ssp. lactis NCIMB 50058 Inoculation method
Modified Miles-Misra, spiral plating or streaking/ ecometry.
Criteria
Recovery on Briggs agar should be within 1 log~0 of recovery on MRS agar.
(ii) Characteristic appearance of colonies Small greyish-white colonies, 1-3 m m diameter, flat or raised, smooth, rough or intermediate. Non-lactic acid bacteria e.g. yeasts and Gram-negative species, may be distinguished by colony size and appearance after further incubation at room temperature.
References Briggs, M.J. (1953) An improved medium for lactobacilli. J. Dairy Res. 20, 36--40. Cox, C.P. and Briggs, M.J. (1954) Experiments on growth media for lactobacilli. J. Appl. Bacteriol. 17, 18-26. Lerche, M. and Reuter, G. (1960) Beitrag zur Methodik der Isolierung und Differenzierung von aerob wachsenden Laktobazillen. Zbl. Bakteriol. I. Orig. 179, 354-370. Reuter, G. (1964) Vergleichsuntersuchungen an 90 thermophilen Lactobazillen Stammen verschiedener Herkunft. Zbl. Bakteriol. I. Orig. 193,454-466.