A polyphasic approach to highlight genotypic and phenotypic diversities of <e1>Lactobacillus helveticus</e1> strains isolated from dairy starter cultures and cheeses

In the present work, 67 strains of <e1>Lactobacillus helveticus</e1> isolated from whey starter cultures and cheeses were identified and grouped by genotypic and phenotypic methods. Strains were identified by sugar fermentation pattern, by cell-wall protein profile, and by probe hybridisation. Phenotypic diversity was evaluated by a chemometric model taking into account biochemical characteristics (i.e. acidifying and peptidase activities) of technological interest. Genotypic diversity was evidenced by RAPD-PCR, which provided strain-specific patterns and revealed the occurrence of different strains. The RAPD-PCR profiles were clustered according to their similarities; the groups obtained, together with the cell-wall protein profiling and the chemometric information, could be sometimes correlated with the type of cheese and/or dairy niches used as sources of strains. A computerised analysis of genotypic and phenotypic information could be successfully applied for rapid and reliable differentiation and characterisation of <e1>Lb. helveticus</e1> isolates occurring in different dairy products.