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Survival of probiotic adjunct cultures in cheese and challenges in their enumeration using selective media.
J Dairy Sci. 2011 May; 94(5):2220-30.JD

Abstract

Various selective media for enumerating probiotic and cheese cultures were screened, with 6 media then used to study survival of probiotic bacteria in full-fat and low-fat Cheddar cheese. Commercial strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus paracasei, or Bifidobacterium lactis were added as probiotic adjuncts. The selective media, designed to promote growth of certain lactic acid bacteria (LAB) over others or to differentiate between LAB, were used to detect individual LAB types during cheese storage. Commercial strains of Lactococcus, Lactobacillus, and Bifidobacterium spp. were initially screened on the 6 selective media along with nonstarter LAB (NSLAB) isolates. The microbial flora of the cheeses was analyzed during 9 mo of storage at 6°C. Many NSLAB were able to grow on media presumed selective for Lactococcus, Bifidobacterium spp., or Lb. acidophilus, which became apparent after 90 d of cheese storage, Between 90 and 120 d of storage, bacterial counts changed on media selective for Bifidobacterium spp., suggesting growth of NSLAB. Appearance of NSLAB on Lb. casei selective media [de man, Rogosa, and Sharpe (MRS)+vancomycin] occurred sooner (30 d) in low-fat cheese than in full-fat control cheeses. Differentiation between NSLAB and Lactococcus was achieved by counting after 18 to 24h when the NSLAB colonies were only pinpoint in size. Growth of NSLAB on the various selective media during aging means that probiotic adjunct cultures added during cheesemaking can only be enumerated with confidence on selective media for up to 3 or 4 mo. After this time, growth of NSLAB obfuscates enumeration of probiotic adjuncts. When adjunct Lb. casei or Lb. paracasei cultures are added during cheesemaking, they appear to remain at high numbers for a long time (9 mo) when counted on MRS+vancomycin medium, but a reasonable probability exists that they have been overtaken by NSLAB, which also grow readily on this medium. Enumeration using multiple selective media can provide insight into whether it is the actual adjunct culture or a NSLAB strain that is being enumerated.

Authors+Show Affiliations

Microbiology Department, Weber State University, Ogden, UT 84408-2506, USA. coberg@weber.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21524512

Citation

Oberg, C J., et al. "Survival of Probiotic Adjunct Cultures in Cheese and Challenges in Their Enumeration Using Selective Media." Journal of Dairy Science, vol. 94, no. 5, 2011, pp. 2220-30.
Oberg CJ, Moyes LV, Domek MJ, et al. Survival of probiotic adjunct cultures in cheese and challenges in their enumeration using selective media. J Dairy Sci. 2011;94(5):2220-30.
Oberg, C. J., Moyes, L. V., Domek, M. J., Brothersen, C., & McMahon, D. J. (2011). Survival of probiotic adjunct cultures in cheese and challenges in their enumeration using selective media. Journal of Dairy Science, 94(5), 2220-30. https://doi.org/10.3168/jds.2010-3934
Oberg CJ, et al. Survival of Probiotic Adjunct Cultures in Cheese and Challenges in Their Enumeration Using Selective Media. J Dairy Sci. 2011;94(5):2220-30. PubMed PMID: 21524512.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Survival of probiotic adjunct cultures in cheese and challenges in their enumeration using selective media. AU - Oberg,C J, AU - Moyes,L V, AU - Domek,M J, AU - Brothersen,C, AU - McMahon,D J, PY - 2010/10/15/received PY - 2011/01/11/accepted PY - 2011/4/29/entrez PY - 2011/4/29/pubmed PY - 2011/8/24/medline SP - 2220 EP - 30 JF - Journal of dairy science JO - J Dairy Sci VL - 94 IS - 5 N2 - Various selective media for enumerating probiotic and cheese cultures were screened, with 6 media then used to study survival of probiotic bacteria in full-fat and low-fat Cheddar cheese. Commercial strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus paracasei, or Bifidobacterium lactis were added as probiotic adjuncts. The selective media, designed to promote growth of certain lactic acid bacteria (LAB) over others or to differentiate between LAB, were used to detect individual LAB types during cheese storage. Commercial strains of Lactococcus, Lactobacillus, and Bifidobacterium spp. were initially screened on the 6 selective media along with nonstarter LAB (NSLAB) isolates. The microbial flora of the cheeses was analyzed during 9 mo of storage at 6°C. Many NSLAB were able to grow on media presumed selective for Lactococcus, Bifidobacterium spp., or Lb. acidophilus, which became apparent after 90 d of cheese storage, Between 90 and 120 d of storage, bacterial counts changed on media selective for Bifidobacterium spp., suggesting growth of NSLAB. Appearance of NSLAB on Lb. casei selective media [de man, Rogosa, and Sharpe (MRS)+vancomycin] occurred sooner (30 d) in low-fat cheese than in full-fat control cheeses. Differentiation between NSLAB and Lactococcus was achieved by counting after 18 to 24h when the NSLAB colonies were only pinpoint in size. Growth of NSLAB on the various selective media during aging means that probiotic adjunct cultures added during cheesemaking can only be enumerated with confidence on selective media for up to 3 or 4 mo. After this time, growth of NSLAB obfuscates enumeration of probiotic adjuncts. When adjunct Lb. casei or Lb. paracasei cultures are added during cheesemaking, they appear to remain at high numbers for a long time (9 mo) when counted on MRS+vancomycin medium, but a reasonable probability exists that they have been overtaken by NSLAB, which also grow readily on this medium. Enumeration using multiple selective media can provide insight into whether it is the actual adjunct culture or a NSLAB strain that is being enumerated. SN - 1525-3198 UR - https://www.unboundmedicine.com/medline/citation/21524512/Survival_of_probiotic_adjunct_cultures_in_cheese_and_challenges_in_their_enumeration_using_selective_media_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0022-0302(11)00198-6 DB - PRIME DP - Unbound Medicine ER -