Biotechnological and health potential of wild non-starter lactic acid bacteria isolated from Italian traditional malga-cheese

Malga-cheese is made only in summer season from raw cow’s milk without addition of starter cultures, in small scale on-farm plants called “Malga”. The typical Malga is located at least 1400 meters above the sea level in alpine region of North Italy. The aims of the present study were to characterize lactic acid bacteria (LAB) at the end of ripening (seven months) and to screen them for technological and health properties in order to evaluate their potential use in dairy applications. Ninety-five non-starter lactic acid bacteria (NS-LAB) were isolated from Malga-cheese at seven months ripening and genotypically characterized combining Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR), species-specific PCR and partial sequencing of 16S rRNA gene. After RAPD-PCR the 95 analysed NS-LAB were grouped in 70 biotypes. The dominant species were Pediococcus pentosaceus (32 isolates) and Lactobacillus paracasei (27 isolates). One representative phage-free strain for each biotype was selected for further bioassay screening including: diacetyl production, biogenic amines (BA) production, amino-peptidase activity, bile salts hydrolyze (BSH) activity, Coniugated Linoleic Acid (CLA) from LA and γ- Aminobutyric acid (GABA) production. Three Lb. parabuchneri biotypes were histamine producers and no isolate showed ability to produce putrescine or cadaverine. Lb. paracasei biotypes were the best diacteyl producer. Four biotypes showed BSH ability. Only two Lb. paracasei biotypes had good amino-peptidase activity toward Leucine. These two Lb. paracasei together with a Lb. rhamnosus biotype also showed a good CLA production. Fifteen biotypes were able to produce GABA amount higher than 5 mgL-1 and the best GABA producer were Lb. plantarum biotypes (biotype 66 was able to produce more than 100 mgL-1 GABA). This study showed that the microbiota present in spontaneously fermented traditional dairy products are a potential source of lactic acid bacteria with potential health-promoting capabilities