AGRE-0064 Isolation of 'New' Starter Cultures from Cheese and Fermented Milk

CURRENT STATE OF THE PROJECT

A total of 5,314 strains of lactic acid bacteria have been isolated from cows, sheep and goats milk and cheese of which 66% have been identified and screened for acid production, proteolysis, polysaccharide production, and bacteriocin production. All genera of LAB, except pediococci, were isolated and, surprisingly enterococci were an important part of the micro flora of Casu Axedu cheese, from Sardinia and leuconostocs of Serra da Estrela cheese, from Portugal. All of these have been frozen at -80°C and a data bank, based on the MAC Hypercard, on the important phenotypic properties should be available by December 1993.

Many of the thermophiles (both rods and cocci) were good acid producers with potential for increasing product quality. In contrast, most of the mesophiles were slow acid producers, with the exception of those isolated in Sardinia. From the relatively limited amount of information available yet, there appears to be no correlation between acid production and proteolysis. Only a limited number of isolates have been checked for polysaccharide production and only three strains (one each from Greece, Italy and Ireland) produce polysaccharides. Considerable variations in the inhibitory spectra of the bacteriocins, produced by different strains was observed and some potentially useful ones, which inhibit e.g. Listeria and Cl. sporogenes were identified.

Probes for identifying the different genera, species and subspecies of lactic acid bacteria, based on the variable 16-SrRNA regions and on an EcoRI fragment of a plasmid have been developed. A course on the use of these probes was held in Cremona Italy and was attended by 25 participants for ECLAIR 0064 and FLAIR 0053.

A set of 6 Str. thermophiles phage which would allow detection of 90% of phage sensitive strains, was identified.

SPECIFIC OBJECTIVES AND SUMMARY

Task 1, the isolation of 5,314 strains is complete while Task 2, the detailed screening and Task 5, the database will be completed in December 1993. Tasks 6 and 7, are also fairly complete with the development of genus, species and subspecies specific probes. The third year of the project will be devoted mainly to tasks 3 and 4 which deal with manufacture of products and developing new dairy products with unusual flavour profiles. Of major significance in this regard is the interchange of potentially useful strains between the different laboratories. In addition, Tasks 2 and 5 will be completed.