Isolation of cultivable thermophilic lactic acid bacteria from cheeses made with mesophilic starter and molecular comparison with dairy-related Lactobacillus helveticus strains

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Marie Elisabeth Penderup Jensen, Ylva Margareta Ardö, Finn Kvist Vogensen

Aims: To isolate cultivable thermophilic lactic acid bacteria from cheeses made with mesophilic starter and compare them with dairy-related Lactobacillus helveticus strains using molecular typing methods.

Methods and Results: The number of thermophilic bacteria in seven commercial cheeses manufactured with mesophilic starters was estimated to be <10 CFU g-1. Implementation of an enumeration step in the isolation method made it possible to isolate one thermophilic strain from each of five of seven cheeses. Comparing repetitive sequence PCR (rep-PCR) profiles of the isolates with dairy-related Lact. helveticus strains indicated that one isolate was a Lact. helveticus. Partial sequencing of 16S rRNA confirmed this, and the remaining four strains were identified as Lactobacillus delbrueckii, Lactobacillus fermentum and Enterococcus faecium. The rep-PCR profile of the isolated Lact. helveticus was identical to the rep-PCR profile of the Lact. helveticus adjunct culture used in the specific cheese, but their pulsed field gel electrophoresis profiles differed slightly.

Conclusion: It was possible to isolate cultivable thermophilic bacteria from ripened cheeses manufactured with mesophilic starter and thermophilic adjunct cultures by using an enumeration step.

Significance and Impact of the Study: Isolation of cultivable thermophilic bacteria from ripened cheeses made with mesophilic starters offers an original source for new dairy-relevant cultures.

Original languageEnglish
JournalLetters in Applied Microbiology
Volume49
Issue number3
Pages (from-to)396-402
Number of pages7
ISSN0266-8254
DOIs
Publication statusPublished - 2009

ID: 15893745